Cover Page - USD ($)	12 Months Ended
Cover Page - USD ($)	Dec. 31, 2025	Jan. 30, 2026	Jun. 30, 2025
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-14756
Entity Registrant Name	Ameren Corporation
Entity Tax Identification Number	43-1723446
Entity Incorporation, State or Country Code	MO
Entity Address, Address Line One	1901 Chouteau Avenue
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63103
City Area Code	(314)
Local Phone Number	621-3222
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol(s)	AEE
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Emerging growth company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 25,948,493,142
Entity Common Stock, Shares Outstanding		276,424,515
Documents Incorporated by Reference	Portions of the definitive proxy statement of Ameren Corporation and portions of the definitive information statements of Union Electric Company and Ameren Illinois Company for the 2026 annual meetings of shareholders are incorporated by reference into Part III of this Form 10-K.
Entity Central Index Key	0001002910
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	false
Ameren Missouri
Entity Information [Line Items]
Current Fiscal Year End Date	--12-31
Entity File Number	1-2967
Entity Registrant Name	Union Electric Company
Entity Tax Identification Number	43-0559760
Entity Incorporation, State or Country Code	MO
Entity Address, Address Line One	1901 Chouteau Avenue
Entity Address, City or Town	St. Louis
Entity Address, State or Province	MO
Entity Address, Postal Zip Code	63103
City Area Code	(314)
Local Phone Number	621-3222
Title of 12(g) Security	Preferred Stock, cumulative, no par value, stated value $100 per share
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Emerging growth company	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		102,123,834
Entity Central Index Key	0000100826
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	false
No Trading Symbol Flag	true
Ameren Illinois
Entity Information [Line Items]
Current Fiscal Year End Date	--12-31
Entity File Number	1-3672
Entity Registrant Name	Ameren Illinois Company
Entity Tax Identification Number	37-0211380
Entity Incorporation, State or Country Code	IL
Entity Address, Address Line One	10 Richard Mark Way
Entity Address, City or Town	Collinsville
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	62234
City Area Code	(618)
Local Phone Number	343-8150
Title of 12(g) Security	Preferred Stock, cumulative, $100 par value
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Emerging growth company	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		25,452,373
Entity Central Index Key	0000018654
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	false
No Trading Symbol Flag	true

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2025
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	St. Louis, Missouri
Auditor Firm ID	238
Ameren Missouri
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	St. Louis, Missouri
Auditor Firm ID	238
Ameren Illinois
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	St. Louis, Missouri
Auditor Firm ID	238

Consolidated Statement Of Income (Loss) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Operating Revenues:
Operating revenues	$ 8,799	$ 7,623	$ 7,500
Operating Expenses:
Utilities Operating Expense, Fuel Used and Purchased Power	2,306	1,681	1,812
Natural gas purchased for resale	348	320	355
Other operations and maintenance	1,974	1,969	1,866
Depreciation and amortization	1,568	1,590	1,387
Taxes other than income taxes	577	547	522
Total operating expenses	6,773	6,107	5,942
Operating Income	2,026	1,516	1,558
Other Income, Net	347	417	348
Interest Charges	776	663	566
Income Before Income Taxes	1,597	1,270	1,340
Income Taxes	136	83	183
Net Income	1,461	1,187	1,157
Less: Net Income Attributable to Noncontrolling Interests	5	5	5
Net Income Attributable to Ameren Common Shareholders	1,456	1,182	1,152
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $1, $—, and $(2), respectively	3	(3)	(5)
Unrealized net gain on derivative hedging instruments, net of income taxes of $2, $—, and $—, respectively	3	3	0
Comprehensive Income	1,467	1,187	1,152
Less: Comprehensive Income Attributable to Noncontrolling Interests	5	5	5
Comprehensive Income Attributable to Ameren Common Shareholders	1,462	1,182	1,147
Preferred Stock Dividends	$ 5	$ 5	$ 5
Earnings per Common Share – Basic
Earnings per Common Share – Basic	$ 5.38	$ 4.43	$ 4.39
Earnings per Common Share – Diluted
Earnings per Common Share – Diluted	$ 5.35	$ 4.42	$ 4.38
Weighted-average Common Shares Outstanding – Basic	270.5	266.8	262.8
Weighted-average Common Shares Outstanding – Diluted	272.2	267.4	263.4
Ameren Missouri
Operating Revenues:
Operating revenues	$ 4,795	$ 3,993	$ 3,859
Operating Expenses:
Utilities Operating Expense, Fuel Used and Purchased Power	1,538	1,071	997
Natural gas purchased for resale	65	60	79
Other operations and maintenance	1,029	1,050	1,003
Depreciation and amortization	860	917	783
Taxes other than income taxes	393	372	360
Total operating expenses	3,885	3,470	3,222
Operating Income	910	523	637
Other Income, Net	180	196	130
Interest Charges	297	244	227
Income Before Income Taxes	793	475	540
Income Taxes	43	(87)	(8)
Net Income	750	562	548
Net Income Attributable to Ameren Common Shareholders	747	559	545
Preferred Stock Dividends	3	3	3
Ameren Illinois
Operating Revenues:
Operating revenues	3,844	3,472	3,482
Operating Expenses:
Purchased power	781	621	820
Natural gas purchased for resale	283	260	276
Other operations and maintenance	945	906	818
Depreciation and amortization	652	619	556
Taxes other than income taxes	169	157	146
Total operating expenses	2,830	2,563	2,616
Operating Income	1,014	909	866
Other Income, Net	136	147	156
Interest Charges	260	241	204
Income Before Income Taxes	890	815	818
Income Taxes	153	193	209
Net Income	737	622	609
Net Income Attributable to Ameren Common Shareholders	735	620	607
Preferred Stock Dividends	2	2	2
Electric
Operating Revenues:
Operating revenues	7,668	6,540	6,439
Electric \| Ameren Missouri
Operating Revenues:
Operating revenues	4,631	3,847	3,694
Electric \| Ameren Illinois
Operating Revenues:
Operating revenues	2,876	2,534	2,585
Natural gas
Operating Revenues:
Operating revenues	1,131	1,083	1,061
Natural gas \| Ameren Missouri
Operating Revenues:
Operating revenues	164	146	165
Natural gas \| Ameren Illinois
Operating Revenues:
Operating revenues	$ 968	$ 938	$ 897

Consolidated Statement Of Income (Loss) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Income Statement [Abstract]
Pension and other postretirement benefit plan activity, tax (benefit)	$ 1	$ 0	$ (2)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax	$ 2	$ 0	$ 0

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Current Assets:
Cash and cash equivalents	$ 13	$ 7
Accounts receivable - trade (less allowance for doubtful accounts)	665	525
Unbilled revenue	415	346
Miscellaneous accounts receivable	107	96
Inventories	774	762
Current regulatory assets	387	366
Other current assets	210	162
Total current assets	2,571	2,264
Property, Plant, and Equipment, Net	39,313	36,304
Investments and Other Assets:
Nuclear decommissioning trust fund	1,526	1,342
Goodwill	411	411
Regulatory Asset, Noncurrent	2,524	2,397
Pension and other postretirement benefits	977	757
Other assets	1,154	1,123
Total investments and other assets	6,592	6,030
TOTAL ASSETS	48,476	44,598
Current Liabilities:
Long-Term Debt, Current Maturities	973	317
Short-term debt	643	1,143
Accounts and wages payable	1,254	1,059
Interest accrued	229	196
Customer deposits	238	223
Other current liabilities	570	475
Total current liabilities	3,907	3,413
Long-Term Debt, Excluding Current Maturities	18,214	17,262
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	5,181	4,474
Regulatory liabilities	6,255	5,897
Asset retirement obligations	849	822
Other deferred credits and liabilities	540	487
Total deferred credits and other liabilities	12,825	11,680
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	3	3
Other paid-in capital, principally premium on common stock	8,106	7,513
Retained earnings	5,292	4,604
Accumulated other comprehensive loss	0	(6)
Total shareholders' equity	13,401	12,114
Noncontrolling Interests	129	129
Total equity	13,530	12,243
TOTAL LIABILITIES AND EQUITY	$ 48,476	$ 44,598

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Accounts receivable - trade, allowance for doubtful accounts	$ 39	$ 30
Regulatory Asset, Noncurrent	2,524	2,397
Long-Term Debt, Current Maturities	973	317
Long-Term Debt, Excluding Current Maturities	$ 18,214	$ 17,262
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000.0	400,000,000.0
Common Stock, Shares, Outstanding	276,400,000	269,900,000
Common Stock, Shares, Issued	276,400,000	269,900,000
Variable Interest Entity, Primary Beneficiary
Regulatory Asset, Noncurrent	$ 443	$ 465
Long-Term Debt, Current Maturities	23	17
Long-Term Debt, Excluding Current Maturities	$ 426	$ 448

Consolidated Balance Sheet - UE - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Current Assets:
Cash and cash equivalents	$ 13	$ 7
Accounts receivable - trade (less allowance for doubtful accounts)	665	525
Unbilled revenue	415	346
Miscellaneous accounts receivable	107	96
Inventories	774	762
Current regulatory assets	387	366
Other current assets	210	162
Total current assets	2,571	2,264
Property, Plant, and Equipment, Net	39,313	36,304
Investments and Other Assets:
Nuclear decommissioning trust fund	1,526	1,342
Regulatory Asset, Noncurrent	2,524	2,397
Pension and other postretirement benefits	977	757
Other assets	1,154	1,123
Total investments and other assets	6,592	6,030
TOTAL ASSETS	48,476	44,598
Current Liabilities:
Long-Term Debt, Current Maturities	973	317
Short-term debt	643	1,143
Accounts and wages payable	1,254	1,059
Interest accrued	229	196
Other current liabilities	570	475
Total current liabilities	3,907	3,413
Long-Term Debt, Excluding Current Maturities	18,214	17,262
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	5,181	4,474
Regulatory liabilities	6,255	5,897
Asset retirement obligations	849	822
Other deferred credits and liabilities	540	487
Total deferred credits and other liabilities	12,825	11,680
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	3	3
Other paid-in capital, principally premium on common stock	8,106	7,513
Retained earnings	5,292	4,604
Total shareholders' equity	13,401	12,114
TOTAL LIABILITIES AND EQUITY	48,476	44,598
Ameren Missouri
Current Assets:
Cash and cash equivalents	6	0
Advances to money pool	0	43
Unbilled revenue	193	170
Miscellaneous accounts receivable	15	33
Inventories	492	514
Current regulatory assets	181	66
Other current assets	119	70
Total current assets	1,305	1,145
Property, Plant, and Equipment, Net	20,604	18,788
Investments and Other Assets:
Nuclear decommissioning trust fund	1,526	1,342
Regulatory Asset, Noncurrent	1,450	1,366
Pension and other postretirement benefits	271	211
Other assets	244	254
Total investments and other assets	3,491	3,173
TOTAL ASSETS	25,400	23,106
Current Liabilities:
Long-Term Debt, Current Maturities	23	17
Short-term debt	471	0
Interest accrued	99	88
Other current liabilities	212	235
Total current liabilities	1,562	1,019
Long-Term Debt, Excluding Current Maturities	8,120	7,671
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	2,702	2,217
Regulatory liabilities	3,324	3,176
Asset retirement obligations	844	818
Other deferred credits and liabilities	184	150
Total deferred credits and other liabilities	7,054	6,361
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	511	511
Other paid-in capital, principally premium on common stock	3,229	3,201
Preferred stock	80	80
Retained earnings	4,757	4,206
Total shareholders' equity	8,577	7,998
TOTAL LIABILITIES AND EQUITY	25,400	23,106
Ameren Missouri \| Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	284	209
Current Liabilities:
Short-term debt	471	0
Accounts and wages payable	696	629
Ameren Missouri \| Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	15	40
Current Liabilities:
Accounts and wages payable	61	50
Long-Term Debt, Excluding Current Maturities	$ 87	$ 57

Consolidated Balance Sheet - UE (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Accounts receivable - trade, allowance for doubtful accounts	$ 39	$ 30
Regulatory Asset, Noncurrent	2,524	2,397
Long-Term Debt, Current Maturities	973	317
Long-Term Debt, Excluding Current Maturities	$ 18,214	$ 17,262
Common stock, shares authorized	400,000,000.0	400,000,000.0
Common Stock, Shares, Outstanding	276,400,000	269,900,000
Variable Interest Entity, Primary Beneficiary
Regulatory Asset, Noncurrent	$ 443	$ 465
Long-Term Debt, Current Maturities	23	17
Long-Term Debt, Excluding Current Maturities	426	448
Ameren Missouri
Accounts receivable - trade, allowance for doubtful accounts	17	12
Regulatory Asset, Noncurrent	1,450	1,366
Long-Term Debt, Current Maturities	23	17
Long-Term Debt, Excluding Current Maturities	$ 8,120	7,671
Common Stock, No Par Value (in dollars per share)	$ 5
Common stock, shares authorized	150,000,000.0
Common Stock, Shares, Outstanding	102,100,000
Ameren Missouri \| Variable Interest Entity, Primary Beneficiary
Regulatory Asset, Noncurrent	$ 443	465
Long-Term Debt, Current Maturities	23	17
Long-Term Debt, Excluding Current Maturities	$ 426	$ 448

Consolidated Balance Sheet - AIC - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Current Assets:
Cash and cash equivalents	$ 13	$ 7
Accounts receivable - trade (less allowance for doubtful accounts)	665	525
Unbilled revenue	415	346
Miscellaneous accounts receivable	107	96
Inventories	774	762
Current regulatory assets	387	366
Other current assets	210	162
Total current assets	2,571	2,264
Property, Plant, and Equipment, Net	39,313	36,304
Investments and Other Assets:
Goodwill	411	411
Regulatory Asset, Noncurrent	2,524	2,397
Pension and other postretirement benefits	977	757
Other assets	1,154	1,123
Total investments and other assets	6,592	6,030
TOTAL ASSETS	48,476	44,598
Current Liabilities:
Long-Term Debt, Current Maturities	973	317
Short-term debt	643	1,143
Accounts and wages payable	1,254	1,059
Interest accrued	229	196
Customer deposits	238	223
Other current liabilities	570	475
Total current liabilities	3,907	3,413
Long-Term Debt, Excluding Current Maturities	18,214	17,262
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	5,181	4,474
Regulatory liabilities	6,255	5,897
Other deferred credits and liabilities	540	487
Total deferred credits and other liabilities	12,825	11,680
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	3	3
Other paid-in capital, principally premium on common stock	8,106	7,513
Retained earnings	5,292	4,604
Total shareholders' equity	13,401	12,114
TOTAL LIABILITIES AND EQUITY	48,476	44,598
Ameren Illinois
Current Assets:
Cash and cash equivalents	3	0
Unbilled revenue	222	175
Miscellaneous accounts receivable	56	28
Inventories	278	244
Prepaid assets	68	59
Current regulatory assets	189	281
Other current assets	6	8
Total current assets	1,204	1,110
Property, Plant, and Equipment, Net	16,567	15,530
Investments and Other Assets:
Goodwill	411	411
Regulatory Asset, Noncurrent	1,059	1,011
Pension and other postretirement benefits	570	471
Other assets	789	697
Total investments and other assets	2,829	2,590
TOTAL ASSETS	20,600	19,230
Current Liabilities:
Long-Term Debt, Current Maturities	0	300
Short-term debt	17	88
Interest accrued	69	59
Customer deposits	204	185
Current regulatory liabilities	132	79
Other current liabilities	227	172
Total current liabilities	1,101	1,318
Long-Term Debt, Excluding Current Maturities	6,254	5,549
Deferred Credits and Other Liabilities:
Accumulated deferred income taxes and production and investment tax credits, net	2,354	2,143
Regulatory liabilities	2,775	2,573
Other deferred credits and liabilities	268	273
Total deferred credits and other liabilities	5,397	4,989
Commitments and Contingencies (Notes 2, 9, and 14)
Shareholders' Equity:
Common stock	0	0
Other paid-in capital, principally premium on common stock	3,058	3,056
Preferred stock	49	49
Retained earnings	4,736	4,266
Total shareholders' equity	7,843	7,371
TOTAL LIABILITIES AND EQUITY	20,600	19,230
Ameren Illinois \| Nonrelated Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	364	300
Current Liabilities:
Short-term debt	17	88
Accounts and wages payable	395	324
Ameren Illinois \| Related Party
Current Assets:
Accounts receivable - trade (less allowance for doubtful accounts)	18	15
Current Liabilities:
Short-term debt	0	37
Accounts and wages payable	57	74
Long-Term Debt, Excluding Current Maturities	$ 5	$ 3

Consolidated Balance Sheet - AIC (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Accounts receivable - trade, allowance for doubtful accounts	$ 39	$ 30
Common stock, shares authorized	400,000,000.0	400,000,000.0
Common Stock, Shares, Outstanding	276,400,000	269,900,000
Ameren Illinois
Accounts receivable - trade, allowance for doubtful accounts	$ 22	$ 18
Common Stock, No Par Value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized	45,000,000.0	45,000,000.0
Common Stock, Shares, Outstanding	25,500,000	25,500,000

Consolidated Statement Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash Flows From Operating Activities:
Net income	$ 1,461	$ 1,187	$ 1,157
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,612	1,524	1,432
Amortization of nuclear fuel	56	81	68
Amortization of debt issuance costs and premium/discounts	19	19	16
Deferred income taxes and production and investment tax credits, net	253	127	229
Allowance for equity funds used during construction	88	76	54
Stock-based compensation costs	28	28	26
Other	63	87	16
Changes in assets and liabilities:
Receivables	(272)	(91)	144
Inventories	(12)	(31)	(67)
Accounts and wages payable	42	4	(104)
Taxes accrued	190	34	(4)
Regulatory assets and liabilities	65	99	(165)
Assets, other	(36)	(34)	(109)
Liabilities, other	104	22	115
Pension and other postretirement benefits	(152)	(216)	(283)
Counterparty collateral, net	20	(1)	147
Net cash provided by operating activities	3,353	2,763	2,564
Cash Flows From Investing Activities:
Capital expenditures	(4,128)	(4,319)	(3,597)
Nuclear fuel expenditures	(46)	(91)	(174)
Purchases of securities – nuclear decommissioning trust fund	(440)	(584)	(266)
Proceeds from sales and maturities	416	564	240
Other	53	(26)	(1)
Net cash used in investing activities	(4,145)	(4,456)	(3,798)
Cash Flows From Financing Activities:
Dividends on common stock	(768)	(714)	(662)
Dividends paid to noncontrolling interest holders	(5)	(5)	(5)
Short-term debt, net	(499)	607	(533)
Maturities and extinguishment of long-term debt	(341)	(893)	(100)
Issuances of long-term debt	1,960	2,535	2,295
Issuances of common stock	574	273	346
Employee payroll taxes related to stock-based compensation	(13)	(8)	(20)
Debt issuance costs	(24)	(31)	(21)
Other	0	(15)	(10)
Net cash provided by financing activities	884	1,749	1,290
Net change in cash, cash equivalents, and restricted cash	92	56	56
Cash, cash equivalents, and restricted cash at beginning of year	328	272	216
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	755	611	546
Income Taxes Paid, Net	(312)	(92)	(24)
Ameren Missouri
Cash Flows From Operating Activities:
Net Income Attributable to Ameren Common Shareholders	750	562	548
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	903	851	827
Amortization of nuclear fuel	56	81	68
Amortization of debt issuance costs and premium/discounts	9	7	7
Deferred income taxes and production and investment tax credits, net	185	(29)	28
Allowance for equity funds used during construction	56	58	30
Other	24	74	(8)
Changes in assets and liabilities:
Receivables	(98)	(26)	39
Inventories	22	(6)	(74)
Accounts and wages payable	10	17	(8)
Taxes accrued	215	60	(17)
Regulatory assets and liabilities	(213)	51	(7)
Assets, other	18	0	(25)
Liabilities, other	27	18	3
Pension and other postretirement benefits	(56)	(76)	(106)
Counterparty collateral, net	7	(3)	96
Net cash provided by operating activities	1,803	1,523	1,341
Cash Flows From Investing Activities:
Capital expenditures	(2,502)	(2,712)	(1,760)
Nuclear fuel expenditures	(46)	(91)	(174)
Purchases of securities – nuclear decommissioning trust fund	(440)	(584)	(266)
Proceeds from sales and maturities	416	564	240
Money pool advances, net	43
Money pool advances, net		(43)	0
Other	0	(32)	0
Net cash used in investing activities	(2,529)	(2,898)	(1,960)
Cash Flows From Financing Activities:
Dividends on common stock	(196)	0	(9)
Dividends on preferred stock	(3)	(3)	(3)
Short-term debt, net	471	(170)	(159)
Money pool borrowings, net	0	(306)	306
Maturities and extinguishment of long-term debt	(17)	(350)	0
Issuances of long-term debt	500	1,771	499
Debt issuance costs	(6)	(21)	(8)
Capital contribution from parent	28	476	0
Other	0	(15)	(10)
Net cash provided by financing activities	777	1,382	616
Net change in cash, cash equivalents, and restricted cash	51	7	(3)
Cash, cash equivalents, and restricted cash at beginning of year	17	10	13
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	312	244	225
Income Taxes Paid, Net	(359)	(136)	(19)
Ameren Illinois
Cash Flows From Operating Activities:
Net Income Attributable to Ameren Common Shareholders	737	622	609
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	652	619	557
Amortization of debt issuance costs and premium/discounts	6	6	5
Deferred income taxes and production and investment tax credits, net	70	188	177
Allowance for equity funds used during construction	30	17	19
Other	45	41	40
Changes in assets and liabilities:
Receivables	(168)	(70)	129
Inventories	(35)	(21)	7
Accounts and wages payable	30	1	(107)
Taxes accrued	(33)	55	(73)
Regulatory assets and liabilities	270	53	(152)
Assets, other	(53)	(33)	(123)
Liabilities, other	62	2	106
Pension and other postretirement benefits	(67)	(88)	(112)
Counterparty collateral, net	12	11	54
Net cash provided by operating activities	1,498	1,369	1,098
Cash Flows From Investing Activities:
Capital expenditures	(1,481)	(1,467)	(1,731)
Other	(3)	1	(2)
Net cash used in investing activities	(1,484)	(1,466)	(1,733)
Cash Flows From Financing Activities:
Dividends on common stock	(265)	(110)	(41)
Dividends on preferred stock	(2)	(2)	(2)
Short-term debt, net	(71)	(277)	102
Money pool borrowings, net	(37)	(98)	135
Maturities and extinguishment of long-term debt	(300)	0	(100)
Issuances of long-term debt	711	624	498
Debt issuance costs	(10)	(8)	(5)
Capital contribution from parent	2	36	91
Net cash provided by financing activities	28	165	678
Net change in cash, cash equivalents, and restricted cash	42	68	43
Cash, cash equivalents, and restricted cash at beginning of year	302	234	191
Cash Paid (Refunded) During the Year:
Interest (net of amounts capitalized, respectively)	242	213	195
Income Taxes Paid, Net	$ 118	$ (46)	$ 102

Consolidated Statement Of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Interest Paid, Capitalized, Investing Activity	$ 52	$ 56	$ 48
Proceeds from Income Tax Refunds	314	95	49
Ameren Missouri
Interest Paid, Capitalized, Investing Activity	36	39	27
Proceeds from Income Tax Refunds	314	95	49
Ameren Illinois
Interest Paid, Capitalized, Investing Activity	$ 15	$ 15	$ 17

Consolidated Statement Of Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Other Paid-In Capital	Retained Earnings	Derivative Financial Instruments	Deferred Retirement Benefit Costs	Accumulated Other Comprehensive Income (Loss)	Total Ameren Corporation Stockholders' Equity	Noncontrolling Interest	Ameren Missouri	Ameren Missouri Common Stock	Ameren Missouri Other Paid-In Capital	Ameren Missouri Preferred Stock Not Subject To Mandatory Redemption	Ameren Missouri Retained Earnings	Ameren Illinois	Ameren Illinois Common Stock	Ameren Illinois Other Paid-In Capital	Ameren Illinois Preferred Stock Not Subject To Mandatory Redemption	Ameren Illinois Retained Earnings
Common Stock at Dec. 31, 2022			$ 6,860	$ 3,646	$ 0	$ (1)			$ 129			$ 2,725		$ 3,111			$ 2,929		$ 3,190
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Value, New Issues			299
Shares issued under the DRPlus and 401(k) plan			46
Stock-based compensation activity			11
Capital contribution from parent										$ 0		0			$ 91		91
Net income	$ 1,157													548					609
Net Income Attributable to Ameren Common Shareholders				1,152						548					609
Common stock dividends				(662)										(9)					(41)
Preferred stock dividends														(3)					(2)
Change in derivative financial instruments					0
Change in deferred retirement benefit costs	(5)					(5)
Net income attributable to noncontrolling interest holders	$ (5)								5
Dividends paid to noncontrolling interest holders									(5)
Beginning of year (shares) at Dec. 31, 2022	262,000,000.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues	3,200,000
Shares issued under the DRPlus and 401(k) plan	600,000
Shares issued (in shares)	500,000
End of year (shares) at Dec. 31, 2023	266,300,000
End of year at Dec. 31, 2023	$ 11,478	$ 3	7,216	4,136	0	(6)	$ (6)		129		$ 511	2,725	$ 80	3,647		$ 0	3,020	$ 49	3,756
Stockholders' equity, end of year at Dec. 31, 2023								$ 11,349		6,963					6,825
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Cash Paid	$ 2.52
Stock Issued During Period, Value, New Issues			233
Shares issued under the DRPlus and 401(k) plan			40
Stock-based compensation activity			24
Capital contribution from parent										476		476			36		36
Net income	$ 1,187													562					622
Net Income Attributable to Ameren Common Shareholders				1,182						562					$ 622
Common stock dividends				(714)										0					(110)
Preferred stock dividends														(3)					(2)
Change in derivative financial instruments					(3)
Change in deferred retirement benefit costs	(3)					(3)
Net income attributable to noncontrolling interest holders	$ (5)								5
Dividends paid to noncontrolling interest holders									(5)
Stock Issued During Period, Shares, New Issues	2,900,000
Shares issued under the DRPlus and 401(k) plan	500,000
Shares issued (in shares)	200,000
End of year (shares) at Dec. 31, 2024	269,900,000														25,500,000
End of year at Dec. 31, 2024	$ 12,243	3	7,513	4,604	3	(9)	(6)		129		511	3,201	80	4,206		0	3,056	49	4,266
Stockholders' equity, end of year at Dec. 31, 2024	$ 12,114							12,114		7,998					$ 7,371
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Cash Paid	$ 2.68
Stock Issued During Period, Value, New Issues			530
Shares issued under the DRPlus and 401(k) plan			44
Stock-based compensation activity			19
Capital contribution from parent										28		28			2		2
Net income	$ 1,461													750					737
Net Income Attributable to Ameren Common Shareholders				1,456						$ 750					$ 737
Common stock dividends				(768)										(196)					(265)
Preferred stock dividends														(3)					(2)
Change in derivative financial instruments					(3)
Change in deferred retirement benefit costs	3					3
Net income attributable to noncontrolling interest holders	$ (5)								5
Dividends paid to noncontrolling interest holders									(5)
Stock Issued During Period, Shares, New Issues	5,800,000
Shares issued under the DRPlus and 401(k) plan	400,000
Shares issued (in shares)	300,000
End of year (shares) at Dec. 31, 2025	276,400,000									102,100,000					25,500,000
End of year at Dec. 31, 2025	$ 13,530	$ 3	$ 8,106	$ 5,292	$ 6	$ (6)	$ 0		$ 129		$ 511	$ 3,229	$ 80	$ 4,757		$ 0	$ 3,058	$ 49	$ 4,736
Stockholders' equity, end of year at Dec. 31, 2025	$ 13,401							$ 13,401		$ 8,577					$ 7,843
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Dividends, Per Share, Cash Paid	$ 2.84

Summary Of Significant Accounting Policies

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Significant Accounting Policies

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

General

Ameren, headquartered in St. Louis, Missouri, is a public utility holding company whose primary assets are its equity interests in its subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below. Ameren also has other subsidiaries that conduct other activities, such as providing shared services.

•Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri. Ameren Missouri was incorporated in Missouri in 1922 and is successor to a number of companies, the oldest of which was organized in 1881. It is the largest electric utility in the state of Missouri. It supplies electric and natural gas service to a 24,000-square-mile area in central and eastern Missouri, which includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.3 million customers and natural gas service to 0.1 million customers.

•Ameren Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric transmission, electric distribution, and natural gas distribution businesses in Illinois. Ameren Illinois was incorporated in Illinois in 1923 and is the successor to a number of companies, the oldest of which was organized in 1902. Ameren Illinois supplies electric and natural gas utility service to a 43,700 square mile area in central and southern Illinois. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 0.8 million customers.

•ATXI operates a FERC rate-regulated electric transmission business in the MISO. ATXI was incorporated in Illinois in 2006.

Ameren’s and Ameren Missouri’s financial statements are prepared on a consolidated basis and therefore include the accounts of their majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren Illinois has no subsidiaries. All tabular dollar amounts are in millions, unless otherwise indicated.

Note 1 – Summary of Significant Accounting Policies applies to the Ameren Companies. The remaining notes to the consolidated financial statements apply to the registrants as indicated in each footnote disclosure. Registrants are named specifically for their related activities and disclosures.

Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair presentation of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.

Regulation

Our customer rates are regulated by the MoPSC, the ICC, and the FERC. We defer certain costs as assets pursuant to actions of rate regulators or because of expectations that we will be able to recover such costs in future rates charged to customers. We also defer certain amounts as liabilities pursuant to actions of rate regulators or based on the expectation that such amounts will be refunded to customers in future rates. Regulatory assets and liabilities are amortized consistent with the period of expected regulatory treatment. See Note 2 – Rate and Regulatory Matters for additional information on our regulatory frameworks, regulatory recovery mechanisms, and regulatory assets and liabilities recorded at December 31, 2025 and 2024.

We periodically assess the recoverability of our regulatory assets and probability of refund of our regulatory liabilities. Regulatory assets are charged to earnings when it is no longer probable that such amounts will be recovered through future revenues. To the extent that refunds to customers related to regulatory liabilities are eliminated by the regulator or are no longer probable, the amounts are credited to earnings.

Cash, Cash Equivalents, and Restricted Cash

Cash and cash equivalents include short-term, highly liquid investments purchased with an original maturity of three months or less. Cash and cash equivalents subject to legal or contractual restrictions and not readily available for use for general corporate purposes are

classified as restricted cash. See Note 15 – Supplemental Information for a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows.

Allowance for Doubtful Accounts Receivable

The allowance for doubtful accounts represents our estimate of existing accounts receivable that will ultimately be uncollectible. The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue. We estimate future collections success using loss factors such as account aging, customer-specific considerations, and forecasted economic conditions. Accounts receivables are written off when all reasonable collection efforts have been completed. Ameren Illinois has bad debt riders that adjust rates for net write-offs of customer accounts receivable above or below those being collected in rates.

Inventories

Inventories are recorded at the lower of weighted-average cost or net realizable value. Inventories are charged to expense or capitalized to property, plant and equipment when issued, as appropriate, using the weighted-average cost method. See Note 15 – Supplemental Information for the components of inventories.

Property, Plant, and Equipment, Net

We capitalize the cost of additions to, and betterments of, units of property, plant, and equipment. The cost includes labor, material, overheads, and applicable taxes. An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets. Maintenance expenditures are expensed as incurred unless subject to regulatory deferral. When units of depreciable tangible property are retired, the original costs, and the associated removal cost, net of salvage, are charged to accumulated depreciation. If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset. See Asset Retirement Obligations and Removal Costs section below and Note 3 – Property, Plant, and Equipment, Net for additional information.

Ameren Missouri’s cost of nuclear fuel is capitalized as a part of “Property, Plant, and Equipment, Net” on Ameren and Ameren Missouri’s balance sheets and then amortized to “Operating Expenses – Fuel and purchased power” in their respective statements of income on a unit-of-production basis. Nuclear fuel amortization is reflected as a part of “Amortization of nuclear fuel” on their respective statements of cash flows.

When it becomes probable an asset will be retired significantly in advance of its previously expected useful life and in the near term, the Ameren Companies must assess the probability of recovery of the remaining net book value of the asset to be abandoned. We recognize a loss on abandonment when it becomes probable that all or part of the cost of an asset, including a return at the applicable WACC, will be disallowed from recovery either through customer rates or through the issuance of securitized utility tariff bonds and such amount is reasonably estimable.

In addition, the Ameren Companies must assess the likelihood of a disallowance that part of the cost of a plant under construction or a recently completed plant will be disallowed for ratemaking purposes. Factors can include our own recent rate orders, as well as recent rate orders of other regulated entities in similar jurisdictions. If a disallowance becomes probable and reasonably estimable, we record an impairment charge in the period in which we determine the plant has met the criteria.

We also evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. Whether an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value of the assets. In the period in which we determine that an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its estimated fair value less cost to sell. We did not identify any material events or changes in circumstances that indicated that the carrying value of long-lived assets may not be recoverable in 2025, 2024, or 2023.

Depreciation

Depreciation is recognized over the estimated lives of the many classes of depreciable tangible property by applying composite rates on a straight-line basis to the original cost of such property. The composite rates include a provision for the estimated removal cost of property, plant, and equipment retired from service, net of salvage. See Asset Retirement Obligation and Removal Costs section below for additional information. The provision for depreciation for the Ameren Companies in 2025, 2024, and 2023 ranged from 3% to 4% of the average depreciable cost. See Note 3 – Property, Plant, and Equipment, Net for additional information on estimated depreciable lives.

Allowance for Funds Used During Construction

As a part of “Property, Plant, and Equipment, Net” on the balance sheet, we capitalize allowance for funds used during construction, which is the cost of borrowed funds and the cost of equity funds (preferred and common shareholders’ equity) applicable to eligible rate-regulated construction work in progress, in accordance with the utility industry’s accounting practice and GAAP. The amount of allowance for funds used during construction is calculated using a FERC-prescribed formula based on a rate, which incorporates the average cost of short-term debt, the average cost of long-term debt, and the cost of equity funds. The portion attributable to borrowed funds is recorded as a reduction of “Interest Charges” on the statements of income. The portion attributable to equity funds is recorded within “Other Income, Net” on the statements of income. This accounting practice offsets the effect on earnings of the cost of financing during construction. See Note 15 – Supplemental Information for the amount of allowance for funds used during construction capitalized and the average rate applied to eligible construction work in progress.

Allowance for funds used during construction does not represent a current source of cash funds. Under accepted ratemaking practice, cash recovery of allowance for funds used during construction and other construction costs occurs when completed projects are placed in service and reflected in customer rates.

Goodwill

Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired. Ameren and Ameren Illinois had goodwill of $411 million at December 31, 2025 and 2024. Ameren has four reporting units: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. Ameren Illinois has three reporting units: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission had goodwill of $238 million, $80 million, and $93 million, respectively, at December 31, 2025 and 2024. The Ameren Transmission reporting unit had the same $93 million of goodwill as the Ameren Illinois Transmission reporting unit at December 31, 2025 and 2024.

Ameren and Ameren Illinois evaluate goodwill for impairment in each of their reporting units as of October 31 each year, or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of their reporting units below their carrying amounts. To determine whether the fair value of a reporting unit is more likely than not greater than its carrying amount, Ameren and Ameren Illinois can elect to perform either a qualitative assessment or to bypass the qualitative assessment and perform a quantitative test.

Ameren and Ameren Illinois elected to perform a qualitative assessment for their annual goodwill impairment test conducted as of October 31, 2025. As part of this qualitative assessment, Ameren and Ameren Illinois evaluated, among other things, macroeconomic conditions, industry and market considerations such as observable industry market multiples, regulatory frameworks, cost factors, overall financial performance, and entity-specific events. The results of Ameren’s and Ameren Illinois’ qualitative assessment indicated that it was more likely than not that the fair value of each reporting unit exceeded its carrying value as of October 31, 2025, resulting in no impairment of Ameren’s or Ameren Illinois’ goodwill.

Variable Interest Entities

Variable Interest Entities that are Consolidated

AMF was formed in 2024, for the purpose of issuing and servicing securitized utility tariff bonds related to costs for the accelerated retirement of the Rush Island Energy Center. Ameren Missouri is the primary beneficiary of this entity because it has the power to direct the activities that most significantly impact the economic performance of the entity, as well as the obligation to absorb losses or the right to receive benefits from the entity. The entity is considered a variable interest entity primarily because its equity capitalization is insufficient to support its operations. The entity’s primary assets and liabilities are comprised of regulatory assets related to the unrecovered net plant balance associated with the retired energy center, among other costs, and long-term debt. Ameren and Ameren Missouri consolidate AMF, which Ameren Missouri wholly owns, and both manages and controls the entity’s operating activities. For additional information on the securitization of the Rush Island Energy Center costs, see Note 2 – Rate and Regulatory Matters. For additional information on the securitized tariff bond issuance, see Note 5 – Long-term Debt and Equity Financings.

The following table presents the carrying values of AMF’s assets and liabilities included on Ameren’s and Ameren Missouri’s consolidated balance sheets as of December 31, 2025 :


	2025		2024
Unbilled revenue (a)	$	2	$	—
Other current assets(a)(b)	21		2
Noncurrent regulatory assets(a)	443		465
Current maturities of long term debt(c)	23		17
Interest accrued (c)	6		1
Current regulatory liabilities(d)	11		—
Long-term debt, net(c)	426		448

(a)Assets may be used only to meet AMF’s obligations and commitments.

(b)Included in “Restricted cash” on Ameren Missouri’s balance sheet.

(c)The securitized tariff bondholders have no recourse to Ameren Missouri.

(d)Included in “Other current liabilities” on Ameren Missouri’s balance sheet.

Variable Interest Entities that are not Consolidated

As of December 31, 2025 and 2024, Ameren had unconsolidated variable interests in various equity method investments, primarily to advance innovative energy technologies, totaling $64 million and $74 million, respectively, included in “Other assets” on Ameren’s consolidated balance sheet. Any earnings or losses related to these investments are included in “Other Income, Net” on Ameren’s consolidated statement of income and comprehensive income. Ameren is not the primary beneficiary of these investments because it does not have the power to direct matters that most significantly affect the activities of these variable interest entities. As of December 31, 2025, the maximum exposure to loss related to these variable interest entities is limited to the investment in these partnerships of $64 million plus associated outstanding funding commitments of $28 million.

Environmental Costs

Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are expensed or deferred as a regulatory asset when it is probable that the costs will be recovered from customers in future rates. See Note 14 – Commitments and Contingencies for additional information on liabilities for environmental costs.

Asset Retirement Obligations and Removal Costs

We record the estimated fair value of legal obligations associated with the retirement of tangible long-lived assets in the period in which the liabilities are incurred and capitalize a corresponding amount as part of the book value of the related long-lived asset. In subsequent periods, we adjust AROs for accretion and changes in the estimated fair values of the obligations, with a corresponding increase or decrease in the asset book value for the fair value changes. Asset book values, reflected within “Property, Plant, and Equipment, Net” on the balance sheet, are depreciated over the remaining useful life of the related asset. Depreciation is deferred as a regulatory balance. The depreciation of the asset book values at Ameren Missouri was $7 million, $2 million, and $9 million for the years ended December 31, 2025, 2024, and 2023, respectively, which was deferred as a reduction to the net regulatory liability. The net regulatory liability also reflects a deferral for the nuclear decommissioning trust fund balance for the Callaway Energy Center. The depreciation deferred to the regulatory asset at Ameren Illinois was immaterial in each respective period. Uncertainties as to the probability, timing, or amount of cash expenditures associated with AROs affect our estimates of fair value. Ameren and Ameren Missouri have recorded AROs for retirement costs associated with decommissioning of Ameren Missouri’s Callaway and wind renewable energy centers, certain Ameren Missouri solar energy centers, CCR facilities, and river structures at certain energy centers used for unloading coal and circulating water systems. Additionally, Ameren, Ameren Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal and the disposal of certain transformers. See Note 15 – Supplemental Information for a reconciliation of the beginning and ending carrying amounts of AROs.

Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment retired from service, represent a cost of removal regulatory liability. See the cost of removal regulatory liability balance in Note 2 – Rate and Regulatory Matters.

COLI

Ameren (parent) and Ameren Illinois have COLI, which is recorded at the net cash surrender value. The net cash surrender value is the amount that can be realized under the insurance policies at the balance sheet date. As of December 31, 2025, the cash surrender value of COLI at Ameren and Ameren Illinois was $219 million (December 31, 2024 – $260 million) and $126 million (December 31, 2024 – $118 million), respectively, while total borrowings against the policies were $117 million (December 31, 2024 – $110 million) at both Ameren and Ameren Illinois. Ameren and Ameren Illinois have the right to offset the borrowings against the cash surrender value of the policies and,

consequently, present the net asset in “Other assets” on their respective balance sheets. The net cash surrender value of Ameren’s COLI is affected by the investment performance of a separate account in which Ameren holds a beneficial interest.

Operating Revenues

We record revenues from contracts with customers for various electric and natural gas services, which primarily consist of retail distribution, electric transmission, and off-system arrangements. When more than one performance obligation exists in a contract, the consideration under the contract is allocated to the performance obligations based on the relative standalone selling price.

Electric and natural gas retail distribution revenues are earned when the commodity is delivered to our customers. We accrue an estimate of electric and natural gas retail distribution revenues for service provided but unbilled at the end of each accounting period. Electric transmission revenues are earned as electric transmission services are provided. Off-system revenues are primarily comprised of MISO revenues and wholesale bilateral revenues. MISO revenues include the sale of electricity, capacity, and ancillary services. Wholesale bilateral revenues include the sale of electricity and capacity. MISO-related electricity and wholesale bilateral electricity revenues are earned as electricity is delivered. Capacity and ancillary service revenues are earned as services are provided.

Retail distribution, electric transmission, and off-system revenues, including the underlying components described above, represent a series of goods or services that are substantially the same and have the same pattern of transfer over time to our customers. Revenues from contracts with customers are equal to the amounts billed and our estimate of electric and natural gas retail distribution services provided but unbilled at the end of each accounting period. Customers are billed at least monthly, and payments are due less than one month after goods and/or services are provided. See Note 16 – Segment Information for disaggregated revenue information.

For certain regulatory recovery mechanisms that are alternative revenue programs rather than revenues from contracts with customers, we recognize revenues that have been authorized for rate recovery, are objectively determinable and probable of recovery, and are expected to be collected from customers within two years from the end of the year. Our alternative revenue programs include revenue requirement reconciliations, the MEEIA, the RBA, the VBA, and the WNAR. These revenues are subsequently recognized as revenues from contracts with customers when billed, with an offset to alternative revenue program revenues.

As of December 31, 2025 and 2024, our remaining performance obligations were immaterial. The Ameren Companies elected not to disclose the aggregate amount of the transaction price allocated to the performance obligations that are unsatisfied as of the end of the reporting period for contracts with an initial expected term of one year or less.

Accounting for MISO Transactions

MISO-related purchase and sale transactions are recorded by Ameren, Ameren Missouri, and Ameren Illinois using settlement information provided by the MISO. Ameren Missouri records these purchase and sale transactions on a net hourly position. Ameren Missouri records net purchases in a single hour in “Operating Expenses – Fuel and purchased power” and net sales in a single hour in “Operating Revenues – Electric” in its statement of income. Ameren Illinois records net purchases in “Operating Expenses – Fuel and purchased power” in its statement of income to reflect all of its MISO transactions relating to the procurement of power for its customers.

Stock-based Compensation

Stock-based compensation cost is measured at the grant date based on the fair value of the award, net of an assumed forfeiture rate. Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite vesting period. To the extent that actual forfeitures differ from estimated forfeitures, such differences are accounted for as an adjustment to compensation expense and recorded in the period that estimates are revised. Compensation cost is ultimately recognized only for awards for which the requisite service was provided. See Note 11 – Stock-based Compensation for additional information.

Unamortized Debt Discounts, Premiums, and Issuance Costs

Long-term debt discounts, premiums, and issuance costs are amortized over the lives of the related issuances. Credit agreement fees are amortized over the term of the agreement.

Income Taxes

Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes. Deferred tax assets and liabilities are recognized for transactions that are treated differently for financial reporting and income tax return purposes. These deferred tax assets and liabilities are based on statutory tax rates.

We expect that regulators will reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate. Therefore, reductions in certain excess deferred tax liabilities that were recorded because of decreases in the statutory

rate have been credited to a regulatory liability. A regulatory asset has been established to recognize the probable recovery through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate increases. To the extent deferred tax balances are included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as a regulatory asset or liability on the balance sheet and will be collected from, or refunded to, customers. For deferred tax balances not included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as an adjustment to income tax expense on the income statement.

Tax credits other than investment tax credits are recognized as a reduction to income tax expense when earned and realizable. The benefits for investment tax credits not transferred under the IRA are amortized over the book depreciable lives of the related property. For production and other tax credits otherwise eligible to be recognized when earned and for investment tax credits transferred under the IRA, Ameren considers the impact of rate regulation to determine if these credits and related adjustments should be deferred as regulatory liabilities. See Note 2 – Rate and Regulatory Matters for additional information on Ameren Missouri’s production and investment tax credit tracker and the RESRAM.

Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren (parent) that provides for the allocation of consolidated tax liabilities. The tax allocation agreement specifies that each subsidiary be allocated an amount of tax using a stand-alone calculation ratio to the total amount of tax owed by the consolidated group. Any net benefit attributable to Ameren (parent) is reallocated to the other subsidiaries. This reallocation is treated as a capital contribution to the subsidiary receiving the benefit. See Note 13 – Related-party Transactions for information regarding capital contributions under the tax allocation agreement.

Accounting and Reporting Developments

Improvements to the Accounting for Internal-Use Software

In September 2025, the FASB issued authoritative guidance that made targeted improvements to the accounting for internal-use software. The guidance requires an entity to capitalize internal-use software costs when management has authorized and committed to funding the software project, and it is probable that the project will be completed and the software will be used to perform its intended function. This guidance will be effective for the Ameren Companies in the first quarter of 2028. We are currently assessing the impacts of this guidance on our results of operations, financial position, and liquidity.

Accounting for Government Grants Received by Business Entities

In December 2025, the FASB issued authoritative guidance that established requirements for the recognition, measurement, presentation, and disclosure of government grants received by business entities. The guidance applies to transfers of monetary or tangible nonmonetary assets from a government to a business entity, excluding income tax credits, below-market loans, and government guarantees. Under this guidance, government grants are recognized when it is probable that a business entity will comply with the grant’s conditions and will receive the grant. This guidance will be effective for the Ameren Companies in the first quarter of 2029. We are currently assessing the impacts of this guidance on our results of operations, financial position, and liquidity.

Rate And Regulatory Matters

12 Months Ended

Dec. 31, 2025

Public Utilities, General Disclosures [Abstract]

Rate and Regulatory Matters

RATE AND REGULATORY MATTERS

Below is a summary of our regulatory frameworks and significant regulatory proceedings and related lawsuits. We are unable to predict the ultimate outcome of these matters, the timing of final decisions of the various agencies and courts, or the effect on our results of operations, financial position, or liquidity.

Regulatory Frameworks

The following table presents the regulatory frameworks and significant regulatory recovery mechanisms for each of Ameren’s rate-regulated businesses, which are discussed in more detail below:

Ameren Missouri

Ameren Illinois’ electric distribution business

Ameren Illinois’ natural gas delivery business

Ameren Illinois’ and ATXI’s electric transmission businesses

Regulatory framework

•Historical test year ratemaking

•Natural gas revenues for residential customers adjusted for sales volume deviations resulting from weather through the WNAR

•MYRP

•Initial rates based on future test years

•Revenues decoupled from sales volumes and wholesale and miscellaneous revenues through the RBA

•Future test year ratemaking

•Revenues for residential and small nonresidential customers decoupled from sales volumes through the VBA

•Formula ratemaking

•Initial rates based on future test year

•Revenues decoupled from sales volumes

Regulatory mechanisms

•PISA

Riders:

•RESRAM

•FAC

•Rush Island securitization

•MEEIA

•PGA

•WNAR

Trackers:

•Pension and postretirement benefit costs

•Certain excess deferred income taxes

•Property taxes

•Production and investment tax credits or proceeds from the sale of certain tax credits allowed under the IRA

•Renewable solutions program revenues and costs(a)

•Electric distribution service and energy-efficiency revenue requirement reconciliation adjustments(b)

Riders:

•RBA

•Power procurement

•Transmission services

•Renewable energy credit compliance

•Zero emission credits

•Customer generation rebate program costs

•Certain environmental costs

•Bad debt write-offs

•Costs of certain asbestos-related claims

Riders:

•PGA

•VBA

•Energy-efficiency program costs

•Certain environmental costs

•Bad debt write-offs

•Invested capital taxes

•Revenue requirement reconciliation adjustment

(a)Ameren Missouri’s renewable solutions program allows certain commercial, industrial, and governmental customers who enroll in the program to receive up to 100% of their energy from renewable resources.

(b)Reconciliation adjustments under an MYRP are subject to a reconciliation cap which limits annual adjustment to 105%. See below for additional information regarding the reconciliation cap.

Missouri

The MoPSC regulates rates and other matters for Ameren Missouri’s electric service and natural gas distribution businesses. The rates Ameren Missouri charges customers for these services are established in a traditional regulatory rate review, which takes up to 11 months to complete, based on a historical test year. Pursuant to the PPRA discussed below, beginning in July 2026, Ameren Missouri will be allowed to file regulatory rate reviews for natural gas delivery service using a future test year, subject to MoPSC approval.

Ameren Missouri has recovery mechanisms, including the RESRAM, FAC, MEEIA, PGA, and WNAR, as well as a rider related to the securitization of the Rush Island Energy Center, that allow customer rates to be adjusted without a traditional regulatory rate review. These riders, along with the PISA, each described in more detail below, partially mitigate the effects of regulatory lag. Ameren Missouri also employs other recovery mechanisms, including a renewable solutions program revenue and cost tracker, as well as electric and natural gas trackers for certain excess deferred income taxes, property taxes, and pension and postretirement benefit costs. Each of these trackers allows Ameren Missouri to defer the difference between actual costs incurred and costs included in customer rates as a regulatory asset or regulatory liability, with the difference expected to be reflected in base rates in a subsequent MoPSC rate order. Ameren Missouri also employs a tracker for the utilization of production and investment tax credits or proceeds from the sale of such tax credits allowed under the IRA. Production and investment tax credits produced by renewable energy centers that support compliance with the state of Missouri’s renewable energy standard, such as the High Prairie, Atchison, and Huck Finn energy centers, are not eligible for tracking under this mechanism as they are included in the RESRAM. Ameren Missouri’s cost recovery under any of its recovery mechanisms is subject to MoPSC prudence reviews.

The PISA permits Ameren Missouri to defer and recover 85% of the depreciation expense for investments in qualifying property, plant, and equipment placed in service and not included in base rates. Investments not eligible for recovery under the PISA include amounts related to new nuclear generation facilities and service to new customer premises. Additionally, the PISA permits Ameren Missouri to earn a return at the applicable WACC on 85% of rate base that incorporates those qualifying investments, as well as changes in total accumulated depreciation excluding retirements and plant-related deferred income taxes since the previous regulatory rate review. The regulatory asset for accumulated PISA deferrals also earns a return at the applicable WACC until added to rate base prospectively. Ameren Missouri recognizes

an offset to “Interest Charges” on its consolidated statement of income for its carrying cost of debt relating to each return allowed under the PISA, with the difference between the applicable WACC and its carrying cost of debt recognized in revenues when recovery of PISA deferrals is reflected in customer rates. Approved PISA deferrals are recovered over a period of 20 years following a regulatory rate review. Additionally, under the RESRAM, Ameren Missouri is permitted to recover the 15% of depreciation expense not recovered under the PISA, and earn a return at the applicable WACC for investments in renewable generation plant placed in service to comply with Missouri’s renewable energy standard. The RESRAM deferrals are a regulatory asset until they are included in customer rates and collected in a subsequent period. Those investments not eligible for recovery under the PISA and the remaining 15% of certain property, plant, and equipment placed in service, unless eligible for recovery under the RESRAM, remain subject to regulatory lag. As a result of the PISA election, additional provisions of the law apply to Ameren Missouri, including limitations on electric customer rate increases caused by the inclusion of incremental PISA deferrals in the revenue requirement. Pursuant to the PPRA discussed below, Ameren Missouri’s PISA election was extended through 2035 and an additional extension through 2040 is allowed if requested by Ameren Missouri and approved by the MoPSC. This law also reduced the annual limit on increases to the electric service revenue requirement used to set customer rates, compared to the revenue requirement established in the immediately preceding rate order, due to the inclusion of incremental PISA deferrals in the revenue requirement. The annual limit in effect was 2.5% and changed to 2.25%, prorated monthly, for revenue requirements approved by the MoPSC after August 2025.

The RESRAM permits Ameren Missouri to recover or refund, through customer rates, the difference between the cost of compliance, net of production and investment tax credits, with Missouri’s renewable energy standard and the amount set in base rates. All sales from the High Prairie, Atchison, and Huck Finn energy centers are included in the RESRAM. Customer rates are adjusted for the RESRAM on an annual basis without a traditional regulatory rate review, subject to MoPSC prudence reviews. The difference between actual compliance costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. RESRAM regulatory assets earn carrying costs at short-term interest rates. The RESRAM permits Ameren Missouri to recover investments in renewable generation related to compliance with Missouri’s renewable energy standard, and earn a return at the applicable WACC on those investments not already provided for in customer rates or any other recovery mechanism.

The FAC permits Ameren Missouri to recover or refund, through customer rates, 95% of the variance in net energy costs from the amount set in base rates without a traditional regulatory rate review, subject to MoPSC prudence reviews, with the remaining 5% of changes retained by Ameren Missouri. As such, Ameren Missouri’s results of operations are affected by the 5% not recovered or refunded under the FAC. The 95% variance in net energy costs in a given period is deferred as a regulatory asset or liability, and is either collected from, or refunded to, customers in a subsequent period. FAC regulatory assets earn carrying costs at short-term interest rates. Ameren Missouri’s base rates for electric service are required to be reset at least every four years to allow for continued use of the FAC.

In 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance $476 million of costs related to the accelerated retirement of the Rush Island Energy Center, which included the remaining unrecovered net plant balance associated with the facility, among other costs. Ameren Missouri is collecting the amounts necessary to repay the bonds through a rider over approximately 15 years beginning in December 2024.

The MEEIA permits Ameren Missouri to recover customer energy-efficiency and demand response program costs, the related lost electric revenues, and any performance incentive through the MEEIA without a traditional regulatory rate review, subject to MoPSC prudence reviews. MEEIA assets earn carrying costs at short-term interest rates.

Ameren Missouri is a member of the MISO, and its transmission rate is calculated in accordance with the MISO Open Access Transmission, Energy, and Operating Reserve Markets Tariff. The FERC regulates the rates charged and the terms and conditions for wholesale electric transmission service. The transmission rate update each June is based on Ameren Missouri’s actual historical cost from the prior calendar year. This rate is not directly charged to Missouri retail customers because, in Missouri, the revenue requirement used to set bundled retail base rates includes an amount for transmission-related costs and revenues.

The PGA allows Ameren Missouri to recover costs of natural gas purchased on behalf of its customers without a traditional regulatory rate review, subject to MoPSC prudence reviews. These pass-through purchased gas costs do not affect Ameren Missouri’s net income, as any change in costs is offset by a corresponding change in revenues. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. PGA regulatory assets earn carrying costs at short-term interest rates.

The WNAR allows Ameren Missouri to adjust natural gas delivery service rates charged to residential customers without a traditional regulatory rate review when deviations from normal weather conditions cause natural gas revenues to vary from the related revenue requirement approved by the MoPSC in the previous regulatory rate review. The impact of deviations from normal weather on natural gas delivery service revenues billed to residential customers in a given period are deferred as a regulatory asset or liability. WNAR regulatory assets earn carrying costs at short-term interest rates. The deferred amount is either collected from, or refunded to, residential customers in a subsequent period.

Illinois

The ICC regulates rates and other matters for Ameren Illinois’ electric distribution service and natural gas distribution businesses. Pursuant to the CEJA, Ameren Illinois may elect to establish electric distribution service rates through either an MYRP or a traditional regulatory rate review based on a future test year. See below for additional information regarding the MYRP approved by the ICC, which established rates effective for 2024 through 2027. The rates Ameren Illinois charges customers for natural gas distribution service are established in a traditional regulatory rate review, which takes up to 11 months to complete, based on a future test year.

Ameren Illinois’ electric distribution service has cost recovery mechanisms in place that allow customer rates to be adjusted without an MYRP or a traditional regulatory rate review. This includes the RBA, which is described in more detail below, and riders for power procurement and transmission services incurred on behalf of its customers, renewable energy credit compliance, zero emission credits, customer generation rebate program costs, and certain environmental costs, as well as bad debt write-offs and the costs of certain asbestos-related claims not recovered in base rates. These pass-through costs do not affect Ameren Illinois’ net income, as any change in costs is offset by a corresponding change in revenues. Ameren Illinois’ cost recovery under any of its recovery mechanisms is subject to ICC prudence reviews.

Under the MYRP, Ameren Illinois is allowed to reconcile its actual electric distribution revenue requirement, as adjusted for certain cost variations, to the ICC-approved revenue requirement on an annual basis, subject to a reconciliation cap. The reconciliation cap limits the annual adjustment to 105% of the annual revenue requirement approved by the ICC. Certain variations from forecasted costs are excluded from the reconciliation cap, including those associated with major storms; new business and facility relocations; changes in the timing of certain expenditures or investments into or out of the applicable calendar year; and changes in interest rates, income taxes, taxes other than income taxes, pension and other post-retirement benefits costs, and amortization of certain assets. The reconciliation cap also excludes costs recovered outside of base rates through riders, such as those described above and the electric energy-efficiency rider discussed below, among others. The actual revenue requirement for a particular year incorporates Ameren Illinois’ year-end rate base and actual capital structure for such year, provided that the resulting revenue requirement does not exceed the 105% reconciliation cap and the common equity ratio in such capital structure may not exceed that approved by the ICC in the MYRP. Ameren Illinois did not exceed the reconciliation cap for the 2024 and 2025 revenue requirements. The 2025 revenue requirement is subject to final reconciliation and ICC review. Ameren Illinois expects to file the 2025 reconciliation with the ICC by May 2026. Subject to the reconciliation cap, if a given year’s actual revenue requirement collected from customers varies from the approved revenue requirement, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue requirement. The regulatory balance is then collected from, or refunded to, customers within two years from the end of the applicable annual period. Regulatory assets applicable to the MYRP earn a return at the applicable WACC. However, Ameren Illinois recognizes the carrying cost of debt on these regulatory assets in revenue, instead of the applicable WACC, with the difference recognized in revenues when recovery of such regulatory assets is reflected in customer rates. Ameren Illinois’ existing riders continue to be effective under the MYRP.

The RBA allows Ameren Illinois to adjust electric distribution service rates charged to customers under an MYRP or a traditional regulatory rate review when electric distribution revenues vary from the related revenue requirement approved by the ICC in the previous MYRP or traditional regulatory rate review. If a given year’s actual revenue billed to customers varies from the approved revenue requirement as a result of sales volumes and/or wholesale and miscellaneous revenue, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue. RBA regulatory assets do not earn carrying costs or a return. The regulatory balance is either collected from, or refunded to, customers within two years from the end of the applicable annual period.

Ameren Illinois used the IEIMA formula framework to establish annual customer electric distribution service rates effective through 2023. Under the framework, Ameren Illinois was allowed to reconcile its revenue requirement for customer rates established through 2023. Ameren Illinois’ 2023 revenues reflected 2023 actual recoverable costs, 2023 year-end rate base, and a return at the applicable WACC, with the ROE component based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points. The 2023 revenue requirement reconciliation adjustment was collected from customers in 2025.

Ameren Illinois’ electric customer energy-efficiency rider provides Ameren Illinois’ electric distribution service business with recovery of, and return on, energy-efficiency investments. Under formula ratemaking for its electric energy-efficiency investments, the revenue requirements are based on recoverable costs, year-end rate base, and a year-end ratemaking capital structure, and earn a return at the applicable WACC. Through 2026, the ROE component of the applicable WACC will continue to be based on the annual average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points and any performance-related basis-point adjustments, described in more detail below. Therefore, Ameren Illinois’ annual ROE for its electric energy-efficiency investments is directly correlated to the yields on such bonds through 2026. Pursuant to the CRGA discussed below, beginning in 2027, the ROE component of the applicable WACC for a given year will be that year’s ICC approved ROE for Ameren Illinois’ electric distribution service. Regulatory assets applicable to formula ratemaking for electric energy-efficiency investments earn a return at the applicable WACC. However, Ameren Illinois recognizes the carrying cost of debt on these regulatory assets in revenue, instead of the applicable WACC, with the difference recognized in revenues when recovery of such regulatory assets is reflected in customer rates.

Ameren Illinois’ electric distribution service business is also subject to performance metrics. Failure to achieve the metrics would result in a reduction in the company’s allowed ROE calculated under the MYRP. In 2022, the ICC issued an order approving total ROE incentives and penalties of 24 basis points under the MYRP, allocated among seven performance metrics. These performance metrics apply annually from 2024 through 2027 under the MYRP, and the impact of any incentives and penalties will be excluded from the reconciliation cap described above. In addition, the allowed ROE on energy-efficiency investments can be increased or decreased up to 200 basis points, depending on the achievement of annual energy savings and demand goals. Any adjustments to the allowed ROE for energy-efficiency investments will depend on annual performance for a historical period relative to energy savings goals. In 2025, 2024, and 2023, there were no performance-related basis-point adjustments that materially affected financial results.

Ameren Illinois’ natural gas distribution business has recovery mechanisms, including the PGA and VBA, that allow customer rates to be adjusted without a traditional regulatory rate review. These riders, described in more detail below, mitigate the effects of regulatory lag. Ameren Illinois employs other riders for natural gas customer energy-efficiency program costs and certain environmental costs, as well as bad debt write-offs and invested capital taxes not recovered in base rates. Pass-through costs under the riders do not affect Ameren Illinois’ net income, as any change in costs is offset by a corresponding change in revenues. Ameren Illinois’ cost recovery under any of its recovery mechanisms is subject to ICC prudence reviews.

The PGA allows Ameren Illinois to recover costs of natural gas purchased on behalf of its customers without a traditional regulatory rate review, subject to ICC prudence reviews. These pass-through purchased gas costs do not affect Ameren Illinois’ net income, as any change in costs is offset by a corresponding change in revenues. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. PGA regulatory assets earn carrying costs at short-term interest rates.

The VBA ensures recoverability of the natural gas distribution service revenue requirement that is dependent on sales volumes for residential and small nonresidential customers. For these rate classes, the VBA allows Ameren Illinois to adjust natural gas distribution service rates without a traditional regulatory rate review when changes occur in sales volumes from those volumes approved by the ICC in a previous regulatory rate review. The difference between allowed sales revenues and amounts billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either collected from, or refunded to, customers in a subsequent period. VBA regulatory assets for a given year that are not fully collected by the end of the following year begin earning carrying costs at short-term interest rates.

Federal

The FERC regulates rates and other matters for Ameren Illinois’ transmission business and ATXI, as well as for Ameren Missouri. See the discussion above related to Ameren Missouri. Both Ameren Illinois and ATXI are members of the MISO, and their transmission rates are calculated in accordance with the MISO Open Access Transmission, Energy, and Operating Reserve Markets Tariff. Ameren Illinois and ATXI have received FERC approval to use a company-specific, forward-looking formula ratemaking framework in setting their transmission rates. These forward-looking rates are updated annually and become effective each January with forecasted information. The formula rate framework provides for an annual reconciliation of the electric transmission service revenue requirement, which reflects the actual recoverable costs incurred and the 13-month average rate base for a given year, with the revenue requirement in customer rates, including an allowed ROE. If a given year’s revenue requirement varies from the amount collected from customers, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue requirement, independent of actual sales volumes. The regulatory balance is collected from, or refunded to, customers within two years from the end of the year. FERC revenue requirement reconciliation adjustment regulatory assets earn carrying costs at each company’s short-term interest rates. In addition, the FERC has approved transmission rate incentives, including a 50-basis-point incentive adder to the allowed base ROE for Ameren Illinois and ATXI for participation in an RTO.

Proceedings and Updates

Missouri

PPRA

The PPRA became effective in August 2025. Pursuant to the law, the PISA has been modified to include new natural gas generating units placed in service after the effective date of the law as qualifying property, plant, and equipment eligible for deferral and recovery of 85% of the related depreciation expense. These new natural gas generating units will also be included in the 85% of rate base allowed to earn a return at the applicable WACC under the PISA. The law also reduced the annual limit on increases to the electric service revenue requirement used to set customer rates, compared to the revenue requirement established in the immediately preceding rate order, due to the inclusion of incremental PISA deferrals in the revenue requirement. The annual limit in effect was 2.5% and changed to 2.25%, prorated monthly, for revenue requirements approved by the MoPSC after August 2025. Furthermore, the PISA's expiration date has been extended through 2035, unless Ameren Missouri requests and receives MoPSC approval of an extension through 2040.

The law also requires an electric utility to develop and submit to the MoPSC schedules that include its service tariff applicable to certain large load customers. These schedules must reasonably ensure that such high-demand customers’ rates reflect a representative share of the costs incurred to serve them and must prevent other lower-demand customer rates from reflecting any unjust or unreasonable costs arising from service provided to these high-demand customers.

In addition, the law made modifications to integrated resource planning, which requires Missouri electric utilities to file plans for meeting their customers' long-term energy needs. By August 2027, the MoPSC will publish a schedule for Missouri electric utilities to file integrated resource plans every four years. The MoPSC will be required to issue an order on the plans and shall determine whether the electric utility has submitted sufficient documentation and selected preferred resource plans representing a reasonable and prudent means of serving the utility's load obligations at just and reasonable rates. In making this determination, the MoPSC shall consider whether the plans appropriately balance specific factors described in the law. If the MoPSC approves the plans, requests for CCNs for new generation facilities to be constructed or acquired as a part of the approved plans shall be deemed necessary and convenient and the scope of the CCN proceedings to review projects will be limited. The approved generation facilities will also be eligible to include construction work in progress in rate base, subject to MoPSC approval, which would improve the timeliness of cash recovery. Utilities are not allowed to capitalize allowance for funds used during construction on amounts included in rate base under this provision. The amount of construction work in progress to be included in rate base is limited to prudently incurred expenditures made within the construction period for the facility.

Further, outside of the integrated resource planning process discussed above, the law allows a Missouri electric utility to request that the MoPSC authorize the inclusion of construction work in progress for new natural gas-fired generation facilities in rate base. Under this provision, utilities are not allowed to capitalize allowance for funds used during construction on projects approved to include construction work in progress in rate base. The amount of construction work in progress to be included in rate base is limited to prudently incurred expenditures made within the construction period for the facility. The provisions allowing for the inclusion of construction work in progress on natural gas-fired generation in rate base expire in December 2035, unless Ameren Missouri requests and receives MoPSC approval of an extension through 2045.

Also, beginning in July 2026 the law allows natural gas utilities to file regulatory rate reviews using a future test year, subject to MoPSC approval. If a natural gas utility is allowed to use a future test year, a reconciliation of the actual rate base and certain forecasted costs will be performed 45 days after the end of the test year. If a given year’s actual revenue requirement is less than the revenue requirement approved by the MoPSC due to changes in rate base or certain other costs, an adjustment is made to reduce natural gas operating revenues with an offset to a regulatory liability to reflect that test year’s amounts. The regulatory liability will then be refunded to customers in the next regulatory rate review and will accrue carrying costs at the applicable WACC.

April 2025 MoPSC Electric Rate Order

In April 2025, the MoPSC issued an order in Ameren Missouri’s 2024 electric service regulatory rate review, approving nonunanimous stipulations and agreements. The order authorized an increase of $355 million to Ameren Missouri’s annual revenue requirement for electric retail service, effective June 1, 2025. The approved revenue requirement was based on infrastructure investments as of December 31, 2024. The order did not explicitly specify an ROE, capital structure, rate base, or any rate base disallowances. The order provides for the continued use of all existing riders and trackers. The order also changed annualized depreciation, regulatory asset and liability amortization amounts, and the base level of expenses for trackers. On an annualized basis, these changes reflect an increase in “Depreciation and amortization” of approximately $70 million, among other expense changes, on Ameren’s and Ameren Missouri’s consolidated statements of income.

July 2025 MoPSC Natural Gas Rate Order

In July 2025, the MoPSC issued an order in Ameren Missouri’s 2024 natural gas delivery service regulatory rate review, approving a unanimous stipulation and agreement. The order authorized an increase of $32 million to Ameren Missouri’s annual revenue requirement for natural gas delivery service, effective September 1, 2025. The order did not explicitly specify an ROE, capital structure, rate base, or any rate base disallowances. The order provides for the continued use of all of Ameren Missouri’s existing riders and trackers.

Large Load Customer Rate Plan

In November 2025, the MoPSC approved Ameren Missouri’s request to modify its existing large primary service tariff, pursuant to the PPRA, to require customers requesting 75 MWs or more of demand and who are served at transmission level voltage to comply with additional tariff terms. The additional terms include a service term of 12 years plus a ramp period of up to five years to reach peak demand, minimum demand charges of 80% of contracted capacity, customer exit terms and fees, and customer credit and collateral requirements, among other terms. In addition, new customer programs would be available under this tariff, which allow customers to support renewable generation, battery storage, and/or nuclear generation through incremental payments. The MoPSC order also includes an earnings sharing mechanism that would apply if Ameren Missouri’s earned ROE for a calendar year exceeds 9.74%, which can be adjusted by the MoPSC in future electric rate orders. If this were to occur, Ameren Missouri would defer 65% of the return in excess of the 9.74% ROE to a regulatory liability, which would be returned to retail electric customers in a future rate review. In addition, if large load customer revenues were reduced in a calendar year due to certain events, as determined by the MoPSC, Ameren Missouri may defer a portion of the reduced revenues to a regulatory asset to be included in its revenue requirement in the next electric rate review. In February 2026, Ameren Missouri executed electric service agreements with large load customers consistent with the tariff terms discussed above, representing 2.2 gigawatts of demand. Ameren and Ameren Missouri do not expect a material impact to their results of operations, financial position, or liquidity in 2026 related to these agreements.

Generation and Storage Facilities

Ameren Missouri is party to agreements to acquire and/or construct various generation and storage facilities that are consistent with the 2025 Change to the 2023 PRP. The generation and storage facilities are eligible for recovery under the PISA. The following table provides information with respect to each facility:

Agreement type

Facility size

Status of MoPSC CCN

In-service date(a)

Vandalia Solar Project(b)

Self-build

50-MW

Approved March 2024

December 2025

Bowling Green Solar Project(b)

Self-build

50-MW

Approved March 2024

First quarter 2026

Split Rail Solar Project

Build-transfer(c)

300-MW

Approved March 2024

Second quarter 2026

Castle Bluff Natural Gas Project(d)

Self-build

800-MW

Approved October 2024

Fourth quarter 2027

Big Hollow Battery Energy Storage Project(e)

Self-build

400-MW

Approved February 2026

Second quarter 2028

Big Hollow Natural Gas Project(e)

Self-build

800-MW

Approved February 2026

Third quarter 2028

Reform Solar Project

Self-build

250-MW

Filed August 2025(f)

Fourth quarter 2028

(a)In-service dates are dependent on the timing of regulatory approvals and construction completion, among other things.

(b)These projects collectively represent approximately $0.2 billion of capital expenditures.

(c)Ameren Missouri received FERC approval for the acquisition in November 2024. In February 2026, Ameren Missouri acquired the Split Rail Solar Project, which includes solar panels, project design, land rights, and engineering, procurement, and construction agreements, for approximately $0.6 billion, and took over construction management of the project.

(d)This project represents approximately $0.9 billion of capital expenditures.

(e)These projects represent approximately $2 billion of capital expenditures.

(f)Ameren Missouri expects a decision by the MoPSC in the first half of 2026.

MEEIA

In 2024, the MoPSC issued an order approving a nonunanimous stipulation and agreement for Ameren Missouri’s MEEIA 2025 plan, which includes a portfolio of customer energy-efficiency and demand response programs, along with the continued use of the MEEIA rider, which allows Ameren Missouri to collect from customers its actual MEEIA program costs, related lost electric revenues, and performance incentives. Ameren Missouri intends to invest $51 million in 2026 and $22 million in 2027 for customer energy-efficiency and demand response programs. In addition, the order approved an immaterial amount of performance incentives applicable to each plan year to earn revenues by achieving certain spending and demand response goals.

MISO Long-Range Transmission Projects CCN

In 2022, the MISO approved the first tranche of projects related to a preliminary long-range transmission planning roadmap of projects through 2039. A portion of these projects were assigned or awarded via a competitive bid process to various utilities, including Ameren. In July and December 2025, the MoPSC issued orders approving requests filed by ATXI for CCNs, among other things, related to the portion of the MISO long-range transmission projects it will construct within the MoPSC’s jurisdiction.

Illinois

MYRP

In December 2024, the ICC issued an order in connection with a revised Grid Plan and a revised MYRP filed by Ameren Illinois in March 2024, approving revenue requirements for electric distribution services for 2024 through 2027 of $1,206 million, $1,287 million, $1,367 million, and $1,421 million, respectively. Using the 2023 revenue requirement as a starting point, the approved revenue requirements in the ICC’s December 2024 order represent a cumulative four-year increase of $308 million. Rate changes consistent with the December 2024 order became effective in December 2024. In March 2025, Ameren Illinois filed an appeal of the ICC’s December 2024 order to the Illinois Appellate Court for the Fifth Judicial District to revise the allowed ROE and to include an asset associated with other postretirement benefits in the rate base, among other things. In addition, Ameren Illinois filed an appeal related to orders issued by the ICC in December 2023 and June 2024 related to the MYRP proceeding. The appellate court is under no deadline to address the appeals, and Ameren Illinois cannot predict the ultimate outcome of the appeals.

2024 Electric Distribution Service Revenue Requirement Reconciliation Adjustment Order

In December 2025, the ICC issued an order approving Ameren Illinois’ 2024 electric distribution service revenue requirement reconciliation adjustment filing. This order approved an adjustment increasing the allowed revenue requirement by $48 million, which reflected Ameren Illinois’ actual 2024 recoverable costs, year-end rate base of $4.2 billion, and capital structure composed of 50% common equity. The approved reconciliation adjustment will be collected from customers in 2026.

In February 2026, the ICC denied Ameren Illinois’ rehearing request to include an asset associated with other postretirement benefits in the rate base, among other things. Ameren Illinois is assessing whether to pursue an appeal with the Illinois Appellate Court for the Fifth Judicial District in the first half of 2026.

Electric Customer Energy-Efficiency Investments

In November 2025, the ICC issued an order in Ameren Illinois’ annual update filing that approved an electric customer energy-efficiency revenue requirement of $138 million beginning in January 2026, which represents an increase of $12 million from the 2025 revenue requirement. This order was based on a projected 2026 year-end rate base of $474 million.

Grid Plan

In January 2026, Ameren Illinois filed its Grid Plan for the years 2028 through 2031. The Grid Plan will be used to align capital expenditures to operational needs and will impact rate base for future rate reviews under an MYRP or traditional rate review. An order from the ICC is expected in December 2026.

Electric Energy Efficiency Plan

In August 2025, the ICC issued an order approving Ameren Illinois’ energy-efficiency plan that includes annual investments in electric energy-efficiency programs of approximately $126 million per year from 2026 through 2029. The ICC has the ability to reduce the amount of electric energy-efficiency savings goals in future program years if there are insufficient cost-effective programs available, which could reduce the investments in electric energy-efficiency programs. Pursuant to the CRGA, Ameren Illinois is required to file an updated energy-efficiency plan for 2027 through 2029 by June 1, 2026 to reflect the spending cap increases discussed below.

CRGA

In January 2026, the CRGA was enacted and will become effective in June 2026. The law includes certain provisions that affect Ameren Illinois’ annual investments in energy-efficiency programs, and the related return on those investments. Under the law, the annual spending cap for energy-efficiency investments will increase to $178 million, $222 million, and $256 million for 2027, 2028, and 2029, respectively. In addition, beginning in 2027, the ROE component of the applicable WACC used to calculate Ameren Illinois’ return on energy-efficiency investments for the year will be that year’s ICC-approved ROE for Ameren Illinois’ electric distribution service. The allowed ROE can be increased or decreased up to 200 basis points, depending on the achievement of annual energy savings and demand goals.

2025 Natural Gas Delivery Service Rate Order

In November 2025, the ICC issued an order in Ameren Illinois’ January 2025 natural gas delivery service regulatory rate review, which resulted in an increase to its annual revenues for natural gas delivery service of $79 million based on a 9.60% ROE, a capital structure composed of 50% common equity, a 2026 future test year, and a rate base of $3.2 billion. The order reflected a reduction of $75 million of

planned distribution and transmission capital investments included in Ameren Illinois’ future test year request. The new rates became effective December 2025.

In January 2026, Ameren Illinois filed an appeal of the ICC’s November 2025 order and the ICC’s January 2026 order rejecting Ameren Illinois’ rehearing request to the Illinois Appellate Court for the Fifth Judicial District. The appeal challenged the inclusion of the non-service cost component of the net periodic benefit income related to other postretirement benefits in the annual revenue requirement and the $75 million reduction of planned capital investments, among other things. The court is under no deadline to address the appeal, and Ameren Illinois cannot predict the ultimate outcome of the appeal.

QIP Reconciliation Hearing

Pursuant to Illinois law, 2014 was the first year of the QIP. In 2021, Ameren Illinois filed a request with the ICC to initiate a reconciliation proceeding of natural gas capital investments recovered under the QIP rider during 2020. Ameren Illinois recovered similar investments in each of the 2014 to 2019 annual reconciliations. In September 2024, the Illinois Attorney General’s office challenged the recovery of capital investments that were made during 2020, alleging that the ICC should disallow $30 million in natural gas capital investments as imprudent, unsupported, or ineligible to be recovered through the QIP resulting in a potential over-recovery of an immaterial amount by Ameren Illinois in 2020. In 2023, and again in 2024, the ICC staff filed testimony that supports the prudence and reasonableness of the capital investments made during 2020. Ameren Illinois’ 2020 QIP rate recovery request under review by the ICC is within the rate increase limitations allowed by law. The ICC is under no deadline to issue an order in this proceeding. Ameren Illinois included $529 million of eligible natural gas capital investments in the QIP from 2021 to 2023. In addition, 2021 through 2023 reconciliation proceedings are still ongoing. Ameren Illinois cannot predict the ultimate outcome of these regulatory proceedings.

MISO Long-Range Transmission Projects CCN

In 2022, the MISO approved the first tranche of projects related to a preliminary long-range transmission planning roadmap of projects through 2039. A portion of these projects were assigned or awarded via a competitive bidding process to various utilities, including Ameren. In July 2025, the ICC issued an order approving a request filed by Ameren Illinois and ATXI for a CCN, among other things, related to the portion of the MISO long-range transmission projects they will construct within the ICC’s jurisdiction.

Federal

MISO Transmission Rate Incentives

In 2024, the MISO approved a first set of second tranche projects related to its preliminary long-range transmission planning roadmap of projects through 2039. A portion of these projects were assigned to Ameren and are estimated to cost approximately $1.3 billion, based on the MISO’s cost estimate. In July 2025, the FERC approved transmission rate incentives relating to the second tranche projects assigned to Ameren. The incentives will allow construction work in progress to be included in rate base for projects constructed by ATXI, thereby improving the timeliness of cash recovery, and would allow recovery of prudently incurred costs, subject to FERC approval, for any portion of the projects if they are abandoned for reasons beyond the control of Ameren. ATXI will not capitalize allowance for funds used during construction on the related projects.

FERC ROE Complaint Cases

Since November 2013, the allowed base ROE for FERC-regulated transmission rate base under the MISO tariff has been subject to customer complaint cases and has been changed by various FERC orders. In October 2024, the FERC issued an order, which decreased the allowed base ROE from 10.02% to 9.98% and required refunds, with interest, for the periods from November 2013 to February 2015 and from late September 2016 forward. In January and April 2025, the MISO transmission owners, including Ameren Missouri, Ameren Illinois, and ATXI, filed appeals of the October 2024 order and a March 2025 FERC order that rejected all rehearing requests to the United States Court of Appeals for the District of Columbia Circuit. The appellate court is under no deadline to address the appeals.

Regulatory Assets and Liabilities

The following table presents our regulatory assets and regulatory liabilities at December 31, 2025 and 2024:


	2025						2024
	Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois		Ameren
Regulatory assets:
Under-recovered FAC(a)	$	137	$	—	$	137	$	41	$	—	$	41


MTM derivative losses(b)	15		111		126		15		88		103

IEIMA revenue requirement reconciliation adjustment(c)(d)	—		—		—		—		139		139
MYRP revenue requirement reconciliation adjustment(d)(e)	—		74		74		—		24		24
Under-recovered RBA(f)	—		29		29		—		22		22
FERC revenue requirement reconciliation adjustment(g)	—		45		73		—		55		90
Under-recovered VBA(h)	—		21		21		—		49		49

Income taxes(i)	282		91		376		237		81		322


Bad debt rider(j)	—		13		13		—		25		25

Callaway refueling and maintenance outage costs(k)	32		—		32		13		—		13
Unamortized loss on reacquired debt(l)	40		4		44		42		5		47
Environmental cost riders(m)	—		46		46		—		43		43
Storm costs(d)(n)	—		15		15		—		18		18





Customer generation rebate program(d)(o)	—		141		141		—		89		89


PISA(d)(p)	558		—		558		464		—		464
Rush Island Energy Center securitization(q)	443		—		443		465		—		465
RESRAM(r)	44		—		44		51		—		51
Certain Meramec Energy Center costs(s)	14		—		14		26		—		26
Energy-efficiency rider(d)(t)	—		624		624		—		576		576
Property tax tracker(u)	18		—		18		22		—		22

Other	48		34		83		56		78		134
Total regulatory assets	$	1,631	$	1,248	$	2,911	$	1,432	$	1,292	$	2,763
Less: current regulatory assets	(181)		(189)		(387)		(66)		(281)		(366)
Noncurrent regulatory assets	$	1,450	$	1,059	$	2,524	$	1,366	$	1,011	$	2,397
Regulatory liabilities:

Over-recovered Illinois electric power costs(v)	—		85		85		—		34		34
Over-recovered PGA(v)	3		39		42		2		33		35

MTM derivative gains(b)	12		4		16		10		6		16





Income taxes(i)	963		546		1,587		1,040		679		1,804



Cost of removal(w)	1,203		1,230		2,511		1,118		1,115		2,294
AROs(x)	841		—		841		691		—		691


Pension and postretirement benefit costs(y)	230		237		467		202		156		358
Pension and postretirement benefit costs tracker(z)	9		—		9		70		—		70


Renewable energy credits and zero emission credits(aa)	—		699		699		—		586		586



Certain Rush Island Energy Center costs(ab)	31		—		31		66		—		66
Rush Island Energy Center base rate revenue deferral(ac)	31		—		31		13		—		13
Other	24		67		94		1		43		50
Total regulatory liabilities	$	3,347	$	2,907	$	6,413	$	3,213	$	2,652	$	6,017
Less: current regulatory liabilities	(23)		(132)		(158)		(37)		(79)		(120)
Noncurrent regulatory liabilities	$	3,324	$	2,775	$	6,255	$	3,176	$	2,573	$	5,897

(a)Under-recovered fuel and purchased power costs to be recovered through the FAC. Specific accumulation periods aggregate the under-recovered costs over four months, any related adjustments that occur over the following four months, and the recovery from customers that occurs over the next eight months.

(b)Deferral of commodity-related derivative MTM losses or gains. See Note 7 – Derivative Financial Instruments for additional information.

(c)The difference between Ameren Illinois’ electric distribution service annual revenue requirement calculated under the IEIMA performance-based formula ratemaking framework and the revenue requirement included in customer rates for that year. The under-recovery was recovered from customers with a return at the applicable WACC in 2025.

(d)These assets earn a return at the applicable WACC.

(e)The difference between Ameren Illinois' actual annual electric distribution revenue requirement, as adjusted for certain cost variations, and the ICC-approved revenue requirement, subject to a reconciliation cap. The under-recovery will be recovered from customers with a return at the applicable WACC within two years.

(f)Under-recovered electric distribution service revenue caused by sales volume and/or wholesale and miscellaneous revenue deviations from the related revenue requirement approved by the ICC for a given year. The under-recovery will be recovered from customers within two years.

(g)Ameren Illinois’ and ATXI’s annual revenue requirement reconciliation calculated pursuant to the FERC’s electric transmission formula ratemaking framework. Any under-recovery or over-recovery will be recovered from, or refunded to, customers within two years.

(h)Under-recovered natural gas revenue caused by sales volume deviations from weather normalized sales approved by the ICC in regulatory rate reviews. Each year’s amount will be recovered from customers from April through December of the following year.

(i)The regulatory assets represent amounts that will be recovered from customers for deferred income taxes related to the equity component of allowance for funds used during construction, the securitization of the Rush Island Energy Center, and the effects of tax rate increases. The regulatory liabilities represent amounts that will be refunded to customers for excess deferred income taxes related to depreciation differences caused by a decrease in the statutory rates, other tax liabilities, and amounts related to the unamortized portion of investment tax credits. Amounts associated with the equity component of allowance for funds used during construction, the securitization of the Rush Island Energy Center, and amounts related to the unamortized portion of investment tax credits will be amortized over the expected life of the related assets. For net regulatory liabilities related to deferred income taxes recorded at rates other than the current statutory rate, the weighted-average remaining amortization periods at Ameren, Ameren Missouri, and Ameren Illinois are 38, 30, and 44 years. In addition, the regulatory liabilities for Ameren Missouri include a regulatory recovery mechanism for the difference between production and investment tax credits or proceeds from the sale of such tax credits allowed under the IRA and the level of such tax credits included in customer rates. The period of refund varies based on MoPSC approval in a regulatory rate review. Amounts included in the accumulation period approved in the April 2025 MoPSC electric rate order, discussed above, are being amortized over five years beginning June 2025. An amortization period for subsequent accumulations will be established in a future rate review.

(j)A rider for the difference between the level of bad debt write-offs, net of any subsequent recoveries, incurred by Ameren Illinois and the level of such costs included in electric distribution and natural gas delivery service rates. Under-recovered or over-recovered costs for each year are collected from, or refunded to, customers over a twelve-month period beginning in June of the following year.

(k)Maintenance expenses related to scheduled refueling and maintenance outages at Ameren Missouri’s Callaway Energy Center. Amounts are amortized over the period between refueling and maintenance outages, which has historically been approximately 18 months.

(l)Losses related to reacquired debt. These amounts are being amortized over the lives of the related new debt issuances or the original lives of the old debt issuances if no new debt was issued.

(m)The recoverable portion of accrued environmental site liabilities that will be collected from electric and natural gas customers through ICC-approved cost recovery riders. The period of recovery will depend on the timing of remediation expenditures. See Note 14 – Commitments and Contingencies for additional information.

(n)Storm costs from 2021 through 2025 deferred in accordance with the IEIMA and MYRP. These costs are being amortized over five-year periods beginning in the year the storm occurred.

(o)Costs associated with Ameren Illinois’ customer generation rebate program. Costs are amortized over a 15-year period, beginning in the year rebates are paid.

(p)Under the PISA, Ameren Missouri is permitted to defer and recover 85% of the depreciation expense and earn a return at the applicable WACC on 85% of investments in certain property, plant, and equipment placed in service and not included in base rates. Accumulated PISA deferrals, which also earn a return at the applicable WACC, are added to rate base prospectively and amortized over a period of 20 years following a regulatory rate review.

(q)In June 2024, the MoPSC issued a financing order authorizing the issuance of securitized utility tariff bonds by AMF to finance costs related to the accelerated retirement of the Rush Island Energy Center, which includes the remaining unrecovered net plant balance associated with the facility, among other costs. Ameren Missouri is collecting the amounts necessary to repay the securitized utility tariff bonds over approximately 15 years beginning in December 2024.

(r)Under-recovered costs associated with Ameren Missouri’s compliance with the state of Missouri’s renewable energy standard. Under-recovered or over-recovered costs are aggregated over a twelve-month period beginning each August and are amortized over a twelve-month period beginning in February of the following year.

(s)Certain costs associated with the Meramec Energy Center, which were authorized for recovery by a December 2021 MoPSC electric rate order. These costs are being collected over five years beginning in February 2022.

(t)The electric energy-efficiency investments are being amortized over their weighted-average useful lives beginning in the period in which they were made, with current remaining amortization periods ranging from one to 13 years.

(u)A regulatory recovery mechanism for the difference between actual property taxes incurred by Ameren Missouri and the related taxes included in customer rates. The period of recovery, or refund, varies based on MoPSC approval in a regulatory rate review. Electric amounts accumulated through 2024 are being amortized over three years beginning June 2025. Gas amounts accumulated through 2024 are being amortized over five years beginning September 2025. For electric and natural gas related costs incurred subsequent to 2024, the amortization period will be determined in a future regulatory rate review.

(v)Over-recovered costs from utility customers. Amounts will be refunded to customers within one year of the deferral.

(w)Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment when retired from service.

(x)The ARO regulatory liability includes the nuclear decommissioning trust fund balance ($1,526 million and $1,342 million at December 31, 2025 and 2024, respectively), net of recoverable removal costs for AROs ($685 million and $651 million at December 31, 2025 and 2024, respectively). See Note 1 – Summary of Significant Accounting Policies – Asset Retirement Obligations and Removal Costs.

(y)Over-recovered costs are being amortized in proportion to the recognition of prior service costs (credits) and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 10 – Retirement Benefits for additional information.

(z)A regulatory recovery mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri and the level of such costs included in customer rates. The period of refund varies based on MoPSC approval in a regulatory rate review. For electric and natural gas related costs incurred through 2024, the weighted-average remaining amortization period is four years. For electric and natural gas related costs incurred subsequent to 2024, the amortization period will be determined in a future regulatory rate review.

(aa)Funds collected for the purchase of renewable energy credits and zero emission credits through IPA procurements. The balance will be amortized as the credits are purchased. Pursuant to the CEJA, if funds collected from customers are not used to procure renewable energy credits, they would be refunded to customers pursuant to an annual reconciliation proceeding, the latest of which was approved by the ICC in May 2025 and did not result in refunds to customers.

(ab)Funds collected from the issuance of securitized utility tariff bonds by AMF primarily to pay for the decommissioning of the Rush Island Energy Center. The amortization period for the difference between the estimated costs and the actual costs incurred will be determined in a future regulatory rate review.

(ac)Base rate revenues related to the Rush Island Energy Center collected after the energy center was retired in October 2024, which is being refunded to customers over three years beginning June 2025.

Property And Plant, Net

12 Months Ended

Dec. 31, 2025

Property, Plant and Equipment [Abstract]

PROPERTY AND PLANT, NET

PROPERTY, PLANT, AND EQUIPMENT, NET

The following table presents components of “Property, plant, and equipment, net” at December 31, 2025 and 2024:


	Ameren Missouri		Ameren Illinois		Other		Ameren
2025
Property, plant, and equipment at original cost(a):
Electric generation:
Coal(b)	$	3,640	$	—	$	—	$	3,640
Natural gas	948		—		—		948
Nuclear	6,255		—		—		6,255
Renewable(c)	3,072		19		—		3,091
Electric distribution	10,205		8,758		—		18,963
Electric transmission	2,479		6,247		2,184		10,910
Natural gas	837		4,642		—		5,479
Other(d)	2,132		1,412		40		3,584
	29,568		21,078		2,224		52,870
Less: Accumulated depreciation and amortization	11,090		5,219		260		16,569
	18,478		15,859		1,964		36,301
Construction work in progress:
Nuclear fuel in progress	194		—		—		194
Other	1,932		708		178		2,818

Property, plant, and equipment, net	$	20,604	$	16,567	$	2,142	$	39,313
2024
Property, plant, and equipment at original cost(a):
Electric generation:
Coal(b)	$	3,556	$	—	$	—	$	3,556
Natural gas	938		—		—		938
Nuclear	5,931		—		—		5,931
Renewable(c)	2,901		19		—		2,920
Electric distribution	9,469		8,160		—		17,629
Electric transmission	2,406		5,725		2,031		10,162
Natural gas	776		4,421		—		5,197
Other(d)	2,427		1,770		260		4,457
	28,404		20,095		2,291		50,790
Less: Accumulated depreciation and amortization	10,875		5,184		436		16,495
	17,529		14,911		1,855		34,295
Construction work in progress:
Nuclear fuel in progress	268		—		—		268
Other	991		619		131		1,741

Property, plant, and equipment, net	$	18,788	$	15,530	$	1,986	$	36,304

(a)The estimated lives for each asset group are as follows: 5 to 72 years for electric generation, excluding Ameren Missouri’s hydroelectric generating assets, which have useful lives of up to 150 years; 20 to 80 years for electric distribution; 50 to 75 years for electric transmission; 15 to 80 years for natural gas; and 2 to 55 years for other.

(b)Includes $30 million of oil-fired generation at December 31, 2025 and 2024.

(c)Renewable includes hydroelectric, wind, solar, and methane gas generation facilities.

(d)Other property, plant, and equipment includes assets used to support electric distribution, electric transmission, and natural gas services.

Capitalized software costs are classified within “Property, Plant, and Equipment, Net” on the balance sheet and are amortized on a straight-line basis over the expected period of benefit, ranging from 2 to 15 years, with the amortization expense included in “Depreciation and amortization” on the statement of income. Deferred cloud implementation costs are classified within “Other Assets” on the balance sheet and are amortized on a straight-line basis over the term of the associated hosting arrangement, ranging from 5 to 15 years, with the amortization expense included in “Other operations and maintenance” on the statement of income. The following table presents the amortization expense, gross carrying value, and related accumulated amortization of capitalized software and deferred cloud implementation costs by year:


	Amortization Expense						Gross Carrying Value				Accumulated Amortization
	2025		2024		2023		2025		2024		2025		2024
Capitalized software costs:
Ameren	$	222	$	224	$	212	$	1,174	$	1,996	$	(572)	$	(1,348)
Ameren Missouri	113		118		114		562		881		(290)		(567)
Ameren Illinois	101		100		92		570		867		(261)		(552)
Deferred cloud implementation costs:
Ameren	$	19	$	20	$	17	$	142	$	157	$	(59)	$	(71)
Ameren Missouri	8		9		8		63		71		(28)		(32)
Ameren Illinois	10		10		9		76		82		(29)		(36)

Annual amortization expense for capitalized software classified as in service as of December 31, 2025, is estimated to be as follows:


	2026		2027		2028		2029		2030
Ameren	$	198	$	152	$	98	$	63	$	32
Ameren Missouri	96		73		46		28		14
Ameren Illinois	96		73		49		32		17

Short-Term Debt And Liquidity

12 Months Ended

Dec. 31, 2025

Line of Credit Facility [Abstract]

SHORT-TERM DEBT AND LIQUIDITY

The liquidity needs of the Ameren Companies are supported through the use of available cash, drawings under committed credit agreements, commercial paper issuances, and/or, in the case of Ameren Missouri and Ameren Illinois, short-term affiliate borrowings.

Short-Term Borrowings

In December 2025, the Credit Agreements, which were scheduled to mature in December 2028, were extended and amended. The Credit Agreements now mature in December 2030. The Credit Agreements provide $3.2 billion of credit cumulatively through maturity. The total facility size of the Missouri Credit Agreement and Illinois Credit Agreement is $1.9 billion and $1.3 billion, respectively. The maturity date of each Credit Agreement may be extended for an additional one-year period upon the mutual consent of the respective borrowers and the lenders. Credit available under the agreements is provided by 20 international, national, and regional lenders, with no single lender providing more than $208 million of lending capacity across both agreements in the aggregate.

The obligations of each borrower under the respective Credit Agreements to which it is a party are several and not joint. Except under limited circumstances relating to expenses and indemnities, the obligations of Ameren Missouri and Ameren Illinois under the respective Credit Agreements are not guaranteed by Ameren (parent) or any other subsidiary of Ameren. The following table presents the maximum aggregate amount available to each borrower under each facility:


	Missouri Credit Agreement		Illinois Credit Agreement
Ameren (parent)	$	1,600	$	800
Ameren Missouri	1,600		(a)
Ameren Illinois	(a)		1,100

(a)Not applicable.

The borrowers have the option to seek additional commitments from existing or new lenders to increase the total facility size of the Credit Agreements to a maximum of $2.4 billion for the Missouri Credit Agreement and $1.6 billion for the Illinois Credit Agreement. Ameren (parent) borrowings are due and payable no later than the maturity date of the Credit Agreements. Ameren Missouri and Ameren Illinois borrowings under the applicable Credit Agreement are due and payable no later than the earlier of the maturity date or 364 days after the date of the borrowing.

The obligations of the borrowers under the Credit Agreements are unsecured. Loans are available on a revolving basis under each of the Credit Agreements. Funds borrowed may be repaid and, subject to satisfaction of the conditions to borrowing, reborrowed from time to

time. At the election of each borrower, the interest rates on such loans will be the alternate base rate plus the margin applicable to the particular borrower and/or the eurodollar rate plus the margin applicable to the particular borrower. The applicable margins will be determined by the borrower’s long-term unsecured credit ratings or, if no such ratings are in effect, the borrower’s corporate/issuer ratings then in effect. The borrowers have received commitments from the lenders to issue letters of credit up to $120 million under each of the Credit Agreements. In addition, the issuance of letters of credit is subject to the $3.2 billion overall combined facility borrowing limitations of the Credit Agreements.

The borrowers will use the proceeds from any borrowings under the Credit Agreements for general corporate purposes. The Missouri Credit Agreement and the Illinois Credit Agreement are available to support issuances under Ameren (parent)’s, Ameren Missouri’s and Ameren Illinois’ commercial paper programs, respectively, subject to borrowing sublimits, as well as to support issuance of letters of credit for the borrowers. Ameren (parent), Ameren Missouri and Ameren Illinois’ use letters of credit to provide financial guarantees for certain operating obligations. As of December 31, 2025, there were $33 million of letters of credit outstanding under the credit facilities, respectively. Amounts approximate their fair value. As of December 31, 2025, based on credit capacity available under the Credit Agreements, along with cash and cash equivalents, the net liquidity available to Ameren (parent), Ameren Missouri, and Ameren Illinois, collectively, was $2.5 billion.

The following table summarizes the activity and relevant interest rates for Ameren (parent)’s, Ameren Missouri’s, and Ameren Illinois’ commercial paper issuances under the Credit Agreements in the aggregate for the years ended December 31, 2025 and 2024:


	Ameren (parent)			Ameren Missouri			Ameren Illinois			Ameren Consolidated
2025
Average daily amount outstanding	$	620		$	223		$	97		$	940
Commercial paper issuances outstanding at period-end	155			471			17			643
Weighted-average interest rate	4.48		%	4.48		%	4.55		%	4.49		%
Peak amount outstanding during period(a)	$	1,139		$	650		$	425		$	1,603
Peak interest rate	4.75		%	4.72		%	4.70		%	4.75		%
2024
Average daily amount outstanding	$	377		$	192		$	193		$	762
Commercial paper issuances outstanding at period-end	1,055			—			88			1,143
Weighted-average interest rate	5.10		%	5.34		%	5.57		%	5.28		%
Peak amount outstanding during period(a)	$	1,091		$	595		$	694		$	1,569
Peak interest rate	5.60		%	5.68		%	5.68		%	5.68		%

(a) The timing of peak outstanding commercial paper issuances and borrowings under the Credit Agreements varies by company. Therefore, the sum of individual company peak amounts may not equal the Ameren consolidated peak amount for the period.

Indebtedness Provisions and Other Covenants

The information below is a summary of the Ameren Companies’ compliance with indebtedness provisions and other covenants.

The Credit Agreements contain conditions for borrowings and issuances of letters of credit. These conditions include the absence of default or unmatured default, material accuracy of representations and warranties (excluding any representation after the closing date as to the absence of material adverse change and material litigation, and the absence of any notice of violation, liability, or requirement under any environmental laws that could have a material adverse effect), and obtaining required regulatory authorizations. In addition, it is a condition for any Ameren Illinois borrowing that, at the time of and after giving effect to such borrowing, Ameren Illinois not be in violation of any limitation on its ability to incur unsecured indebtedness contained in its articles of incorporation.

The Credit Agreements also contain nonfinancial covenants, including restrictions on the ability to incur certain liens, to transact with affiliates, to dispose of assets, to make investments in or transfer assets to its affiliates, and to merge with other entities. The Credit Agreements require each of Ameren, Ameren Missouri, and Ameren Illinois to maintain consolidated indebtedness of not more than 67.5%, 65%, and 65%, respectively, of its consolidated total capitalization pursuant to a defined calculation set forth in the agreements. As of December 31, 2025, the ratios of consolidated indebtedness to total consolidated capitalization, calculated in accordance with the provisions of the Credit Agreements, were 59%, 49%, and 45%, for Ameren, Ameren Missouri, and Ameren Illinois, respectively.

The Credit Agreements contain default provisions that apply separately to each borrower. However, a default of Ameren Missouri or Ameren Illinois under the applicable credit agreement is also deemed to constitute a default of Ameren (parent) under such agreement. Defaults include a cross-default resulting from a default of such borrower under any other agreement covering outstanding indebtedness of such borrower and certain subsidiaries (other than project finance subsidiaries, nonmaterial subsidiaries, and certain special purposes entities contemplated in the Credit Agreements) in excess of $150 million in the aggregate (including under the other credit agreement). However, under the default provisions of the Credit Agreements, any default of Ameren (parent) under either credit agreement that results solely from a default of Ameren Missouri or Ameren Illinois does not result in a cross-default of Ameren (parent) under the other credit agreement. Further, the Credit Agreements default provisions provide that an Ameren (parent) default under either of the Credit Agreements does not constitute a default by Ameren Missouri or Ameren Illinois.

None of the Credit Agreements or financing agreements contain credit rating triggers that would cause a default or acceleration of repayment of outstanding balances. The Ameren Companies were in compliance with the provisions and covenants of the Credit Agreements at December 31, 2025.

Money Pools

Ameren (parent) has money pool agreements with and among its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements.

Ameren Missouri, Ameren Illinois, and ATXI may participate in the utility money pool as both lenders and borrowers. Ameren (parent) and Ameren Services may participate in the utility money pool only as lenders. Surplus internal funds are contributed to the money pool from participants. The primary sources of external funds for the utility money pool are the Credit Agreements and the commercial paper programs. The total amount available to the pool participants from the utility money pool at any given time is reduced by the amount of borrowings made by participants, but it is increased to the extent that the pool participants advance surplus funds to the utility money pool or remit funds from other external sources. The availability of funds is also determined by funding requirement limits established by regulatory authorizations. Participants receiving a loan under the utility money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the utility money pool. The average interest rate for borrowing under the utility money pool for the year ended December 31, 2025, was 4.39% (2024 – 5.19%).

See Note 13 – Related-party Transactions for the amount of interest income and expense from the utility money pool agreement recorded by Ameren Missouri and Ameren Illinois for the years ended December 31, 2025, 2024, and 2023.

Long-Term Debt And Equity Financings

12 Months Ended

Dec. 31, 2025

Long-Term Debt And Equity Financings [Abstract]

LONG-TERM DEBT AND EQUITY FINANCINGS

The following table presents long-term debt outstanding, including maturities due within one year, as of December 31, 2025 and 2024:


	2025		2024
Ameren (Parent):


3.65% Senior unsecured notes due 2026	350		350
5.70% Senior unsecured notes due 2026	600		600
1.95% Senior unsecured notes due 2027	500		500
1.75% Senior unsecured notes due 2028	450		450
5.00% Senior unsecured notes due 2029	700		700
3.50% Senior unsecured notes due 2031	800		800
5.375% Senior unsecured debt due 2035	750		—
Total long-term debt, gross	4,150		3,400
Less: Unamortized discount and premium	(3)		(3)
Less: Unamortized debt issuance costs	(16)		(14)
Less: Maturities due within one year	(950)		—
Long-term debt, net	$	3,181	$	3,383
Ameren Missouri:
Bonds and notes:

2.95% Senior secured notes due 2027(a)	$	400	$	400
3.50% First mortgage bonds due 2029(b)	450		450
2.95% First mortgage bonds due 2030(b)	465		465
2.15% First mortgage bonds due 2032(b)	525		525
2.90% 1998 Series A bonds due 2033(c)	60		60
2.90% 1998 Series B bonds due 2033(c)	50		50
2.75% 1998 Series C bonds due 2033(c)	50		50
5.20% First mortgage bonds due 2034(b)	500		500
5.50% Senior secured notes due 2034(a)	184		184
5.25% First mortgage bonds due 2035(b)	500		—
5.30% Senior secured notes due 2037(a)	300		300
8.45% Senior secured notes due 2039(a)(d)	350		350
4.85% Securitized utility tariff bonds due 2039(e)	459		476
3.90% Senior secured notes due 2042(a)(d)	485		485
3.65% Senior secured notes due 2045(a)	400		400
4.00% First mortgage bonds due 2048(b)	425		425
3.25% First mortgage bonds due 2049(b)	330		330
2.625% First mortgage bonds due 2051(b)	550		550
3.90% First mortgage bonds due 2052(b)	525		525
5.45% First mortgage bonds due 2053(b)	500		500
5.25% First mortgage bonds due 2054(b)	350		350
5.125% First mortgage bonds due 2055(b)	450		450
Total long-term debt, gross	8,308		7,825
Less: Long-term debt – related parties, gross	(88)		(58)
Less: Unamortized discount and premium	(15)		(17)
Less: Unamortized debt issuance costs	(62)		(62)
Less: Maturities due within one year	(23)		(17)
Long-term debt, net	$	8,120	$	7,671


	2025		2024
Ameren Illinois:
Bonds and notes:
3.25% Senior secured notes due 2025(f)	—		300
6.125% Senior secured notes due 2028(f)	60		60
3.80% First mortgage bonds due 2028(g)	430		430
1.55% First mortgage bonds due 2030(g)	375		375
3.85% First mortgage bonds due 2032(g)	500		500
4.95% First mortgage bonds due 2033(g)	500		500
6.70% Senior secured notes due 2036(f)	61		61
6.70% Senior secured notes due 2036(f)	42		42
4.80% Senior secured notes due 2043(f)	280		280
4.30% Senior secured notes due 2044(f)	250		250
4.15% Senior secured notes due 2046(f)	490		490
3.70% First mortgage bonds due 2047(g)	500		500
4.50% First mortgage bonds due 2049(g)	500		500
3.25% First mortgage bonds due 2050(g)	300		300
2.90% First mortgage bonds due 2051(g)	350		350
5.90% First mortgage bonds due 2052(g)	350		350
5.55% First mortgage bonds due 2054(g)	625		625
5.625% First mortgage bonds due 2055(g)	700		—
Total long-term debt, gross	6,313		5,913
Less: Long-term debt – related parties, gross	(5)		(3)
Less: Unamortized discount and premium	2		(10)
Less: Unamortized debt issuance costs	(56)		(51)
Less: Maturities due within one year	—		(300)
Long-term debt, net	$	6,254	$	5,549
ATXI:
2.45% Senior unsecured notes due 2036(h)	$	75	$	75
5.17% Senior unsecured notes due 2039	70		70
3.43% Senior unsecured notes due 2050(i)	351		351
2.96% Senior unsecured notes due 2052(j)	95		95
5.42% Senior unsecured notes due 2053	70		70
Total long-term debt, gross	661		661

Less: Unamortized debt issuance costs	(2)		(2)

Long-term debt, net	$	659	$	659
Ameren consolidated long-term debt, net	$	18,214	$	17,262

(a)These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the 2055 maturity date of the 5.125% first mortgage bonds and the restrictions preventing a release date to occur that are attached to certain senior secured notes described in footnote (d) below, Ameren Missouri does not expect the first mortgage lien protection associated with these notes to fall away.

(b)These bonds are first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. They are secured by substantially all Ameren Missouri property and franchises.

(c)These bonds are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture and have a fall-away lien provision similar to that of Ameren Missouri’s senior secured notes.

(d)Ameren Missouri has agreed that so long as any of the 3.90% senior secured notes due 2042 are outstanding, Ameren Missouri will not permit a release date to occur, and so long as any of the 8.45% senior secured notes due 2039 are outstanding, Ameren Missouri will not optionally redeem, purchase, or otherwise retire in full the outstanding first mortgage bonds not subject to release provisions.

(e)These bonds were issued by AMF. The bondholders of AMF have no recourse to Ameren Missouri’s assets. Ameren Missouri collects securitization surcharges to cover the principal and interest on the bonds as well as certain other qualified costs. The surcharges collected by Ameren Missouri on behalf of AMF are remitted to AMF and are not available to creditors of Ameren Missouri. Principal and interest payments on these bonds are payable semiannually on April 1 and October 1 of each year, which began on October 1, 2025, with final principal and interest payment due October 1, 2039.

(f)These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Illinois mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the 2055 maturity date of the 5.625% first mortgage bonds, Ameren Illinois does not expect the first mortgage lien protection associated with these notes to fall away.

(g)These bonds are first mortgage bonds issued by Ameren Illinois under the Ameren Illinois mortgage indenture. They are secured by substantially all Ameren Illinois property and franchises.

(h)The following table presents the principal maturities schedule for the 2.45% senior unsecured notes due 2036:


Payment Date		Principal Payment
November 2029	$	30
November 2036		45
Total	$	75

(i)The following table presents the principal maturities schedule for the 3.43% senior unsecured notes due 2050:


Payment Date		Principal Payment
August 2027	$	50
August 2030		49
August 2032		50
August 2038		49
August 2043		77
August 2050		76
Total	$	351

(j)The following table presents the principal maturities schedule for the 2.96% senior unsecured notes due 2052:


Payment Date		Principal Payment
August 2040	$	45
August 2052		50
Total	$	95

The following table presents the aggregate maturities of long-term debt, including current maturities, at December 31, 2025:


	Ameren (parent)(a)		Ameren Missouri(a)		Ameren Illinois(a)		ATXI(a)		Ameren Consolidated(a)
2026	$	950	$	23	$	—	$	—	$	973
2027	500		424		—		50		974
2028	450		26		490		—		966
2029	700		477		—		30		1,207
2030	—		493		375		49		917
Thereafter	1,550		6,864		5,448		532		14,394
Total	$	4,150	$	8,307	$	6,313	$	661	$	19,431

(a)Excludes unamortized discount, premium, and debt issuance costs of $19 million, $77 million, $54 million, and $2 million at Ameren (parent), Ameren Missouri, Ameren Illinois, and ATXI, respectively.

In November and December 2024, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri and first mortgage bonds issued by Ameren Illinois for $44 million in the aggregate. In June 2025, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri and first mortgage bonds issued by Ameren Illinois for $24 million in the aggregate. On a consolidated basis, Ameren (parent)’s repurchase of these senior secured notes and first mortgage bonds were accounted for as a debt extinguishment and resulted in a pre-tax gain of $8 million and $16 million for the years ended December 31, 2025 and 2024, respectively, which is reflected in “Other Income, Net” on Ameren’s consolidated statement of income. Interest expense related to the repurchased bonds was $3 million and less than $1 million for the years ended December 31, 2025 and 2024, respectively.

The following table presents Ameren Missouri’s and Ameren Illinois’ “Long-term Debt, Net - Related Parties” as of December 31, 2025 and 2024:


	2025		2024
Ameren Missouri:
3.65% Senior secured notes due 2045	$	29	$	7
4.00% First mortgage bonds due 2048	4		—
3.25% First mortgage bonds due 2049	33		33
2.625% First mortgage bonds due 2051	7		4
3.90% First mortgage bonds due 2052	15		14
Total long-term debt - related parties, gross	88		58

Less: Unamortized debt issuance costs	(1)		(1)

Long-term debt - related parties, net	$	87	$	57
Ameren Illinois:
3.70% First mortgage bonds due 2047	$	1	$	1
3.25% First mortgage bonds due 2050	2		2




2.90% First mortgage bonds due 2051	2		—
Long-term debt - related parties, net	$	5	$	3

All classes of Ameren Missouri’s and Ameren Illinois’ preferred stock are entitled to cumulative dividends, have voting rights, and are not subject to mandatory redemption. The preferred stock of Ameren’s subsidiaries is included in “Noncontrolling Interests” on Ameren’s consolidated balance sheet. The following table presents the outstanding preferred stock of Ameren Missouri and Ameren Illinois, which is redeemable at the option of the issuer, at the prices shown below as of December 31, 2025 and 2024:


	Shares Outstanding	Redemption Price (per share)			2025		2024
Ameren Missouri:
Without par value and stated value of $100 per share, 25 million shares authorized
$3.50 Series	130,000 shares	$	110.00		$	13	$	13
$3.70 Series	40,000 shares	104.75			4		4
$4.00 Series	150,000 shares	105.625			15		15
$4.30 Series	40,000 shares	105.00			4		4
$4.50 Series	213,595 shares	110.00		(a)	21		21
$4.56 Series	200,000 shares	102.47			20		20
$4.75 Series	20,000 shares	102.176			2		2
$5.50 Series A	14,000 shares	110.00			1		1
Total					$	80	$	80
Ameren Illinois:
With par value of $100 per share, 2 million shares authorized
4.00% Series	144,275 shares	$	101.00		$	14	$	14
4.08% Series	45,224 shares	103.00			5		5
4.20% Series	23,655 shares	104.00			2		2
4.25% Series	50,000 shares	102.00			5		5
4.26% Series	16,621 shares	103.00			2		2
4.42% Series	16,190 shares	103.00			2		2
4.70% Series	18,429 shares	104.30			2		2
4.90% Series	73,825 shares	102.00			7		7
4.92% Series	49,289 shares	103.50			5		5
5.16% Series	50,000 shares	102.00			5		5


Total					$	49	$	49
Total Ameren					$	129	$	129

(a)In the event of voluntary liquidation, $105.50.

Ameren has 100 million shares of $0.01 par value preferred stock authorized, with no such shares outstanding. Ameren Missouri has 7.5 million shares of $1 par value preference stock authorized, with no such shares outstanding. Ameren Illinois has 2.6 million shares of no par value preferred stock authorized, with no such shares outstanding.

Ameren

Under the DRPlus and its 401(k) plan, Ameren issued 0.4 million, 0.5 million, and 0.6 million shares of common stock in 2025, 2024, and 2023, respectively, received proceeds of $37 million, $33 million, and $39 million for the respective years, and had a receivable of $7 million and $7 million as of December 31, 2025 and 2024. In addition, Ameren issued 0.3 million, 0.2 million, and 0.5 million shares of common stock valued at $25 million, $16 million, and $40 million in 2025, 2024, 2023, respectively, for no cash consideration in connection with stock-based compensation.

In May 2023, Ameren filed a Form S-3 registration statement with the SEC, authorizing the offering of 3 million additional shares of its common stock under the DRPlus, which expires in May 2026. Shares of common stock sold under the DRPlus are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated contracts.

In October 2023, Ameren, Ameren Missouri, and Ameren Illinois filed a Form S-3 shelf registration statement with the SEC, registering the issuance of an unspecified amount of certain types of securities. This registration statement expires in October 2026.

In May 2022, Ameren filed a Form S-8 registration statement with the SEC, authorizing the offering of 7.5 million additional shares of its common stock under its 401(k) plan. Shares of common stock issuable under the 401(k) plan are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated contracts.

Ameren has entered into an equity distribution sales agreement pursuant to which Ameren may offer and sell from time to time its common stock through an ATM program, which includes the ability to enter into forward sale agreements. In August 2025, Ameren increased the amount of common stock available for sale under the ATM program by $1.25 billion to a total of $3 billion. Under the ATM, Ameren issued 5.8 million, 2.9 million, and 3.2 million shares of common stock and received proceeds of $530 million, $233 million, and $299 million in 2025, 2024 and 2023, respectively. These proceeds were net of $5 million, $2 million and $3 million, respectively, in compensation paid to selling agents. As of December 31, 2025, Ameren had approximately $1.5 billion of common stock remaining available for sale under the ATM program.

In May 2025, Ameren entered into forward sale agreements separate from the ATM program with multiple counterparties relating to 6.4 million shares of common stock, with an initial forward sale price for the agreements of $91.89. The forward sale agreements can be settled at Ameren’s discretion on or prior to January 15, 2027. On a settlement date or dates, if Ameren elects to physically settle a forward sale agreement, Ameren will issue shares of common stock to the counterparties at the then-applicable forward sale price. Each initial forward sale price is subject to adjustment based on a floating interest rate factor equal to the overnight bank funding rate less a spread of 75 basis points, and will be subject to decrease on certain dates specified in the forward sale agreements by specified amounts related to expected dividends on shares of the common stock during the term of the forward sale agreements. If the overnight bank funding rate is less than or more than the spread on any day, the interest rate factor will result in a reduction or an increase, respectively, of the forward sale price. The forward sale agreements will be physically settled unless Ameren elects to settle in cash or to net share settle.

At December 31, 2025, Ameren could have settled the forward sale agreements with physical delivery of 6.4 million shares of common stock to the respective counterparties in exchange for cash of $585 million. Alternatively, the forward sale agreements could have also been settled at December 31, 2025, with delivery of approximately $52 million of cash or approximately 0.5 million shares of common stock to the counterparties. In connection to the forward sale agreements, the various counterparties, or their affiliates, borrowed from third parties and sold 6.4 million shares of common stock. The gross sales price of these shares totaled $600 million. Ameren does not receive any proceeds from such sales of borrowed shares. The forward sale agreements have been classified as equity transactions.

In February 2026, $350 million principal amount of Ameren (parent)’s 3.65% senior unsecured notes matured and was repaid with commercial paper borrowings.

In March 2025, Ameren (parent) issued $750 million of 5.375% senior unsecured notes due March 2035, with interest payable semiannually on March 15 and September 15 of each year, beginning September 15, 2025. Net proceeds from this issuance were used for general corporate purposes, including the repayment of short-term debt.

In September 2024, $450 million principal amount of Ameren (parent)’s 2.50% senior unsecured notes matured and was repaid with commercial paper borrowings.

Ameren Missouri

In April 2025, Ameren Missouri issued $500 million of 5.25% first mortgage bonds due April 2035, with interest payable semiannually on April 15 and October 15 of each year, beginning October 15, 2025. Net proceeds from this issuance were used to repay short-term debt.

In January 2024, Ameren Missouri issued $350 million of 5.25% first mortgage bonds due January 2054, with interest payable semiannually on January 15 and July 15 of each year, beginning July 15, 2024. Net proceeds from this issuance were used for capital expenditures and to repay short-term debt.

In April 2024, Ameren Missouri issued $500 million of 5.20% first mortgage bonds due April 2034, with interest payable semiannually on April 1 and October 1 of each year, beginning October 1, 2024. Net proceeds from this issuance were used for capital expenditures and to repay short-term debt.

In April 2024, $350 million principal amount of Ameren Missouri’s 3.50% senior secured notes matured and was repaid with cash on hand.

In October 2024, Ameren Missouri issued $450 million of 5.125% first mortgage bonds due March 2055, with interest payable semiannually on March 15 and September 15 of each year, beginning March 15, 2025. Net proceeds from this issuance were used for capital expenditures and to repay short-term debt.

In December 2024, AMF issued $476 million of 4.85% securitized utility tariff bonds due October 2039, with principal and interest payable semiannually on April 1 and October 1 of each year, beginning October 1, 2025. Net proceeds from this issuance were used to finance energy transition costs related to the accelerated retirement of the Rush Island Energy Center, which included the remaining unrecovered net plant balance associated with the facility, among other costs, and to repay short-term debt. See Note 2 – Rate and Regulatory Matters for additional information on the securitization of Rush Island Energy Center costs.

For information on Ameren Missouri’s capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions.

Ameren Illinois

In March and September 2025, Ameren Illinois issued $350 million and $350 million, respectively, of 5.625% first mortgage bonds due March 2055, with interest payable semiannually on March 1 and September 1 of each year, beginning September 1, 2025 and March 1, 2026, respectively. Net proceeds from the March 2025 issuance were used to repay $300 million principal amount of its 3.25% senior secured notes that matured in March 2025, and net proceeds of both issuances were used to repay a portion of its short-term debt.

In June 2024, Ameren Illinois issued $625 million of 5.55% first mortgage bonds due July 2054, with interest payable semiannually on January 1 and July 1 of each year, beginning January 1, 2025. Net proceeds from this issuance were used to repay short-term debt.

For information on Ameren Illinois’ capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions.

ATXI

In August 2024, ATXI issued $70 million of 5.17% senior unsecured notes due September 2039 and $70 million of 5.42% senior unsecured notes due September 2053, pursuant to an August 2024 note purchase agreement. Both series of senior unsecured notes have interest payable semiannually on March 1 and September 1 of each year, which began on March 1, 2025, and were issued through a private placement offering exempt from registration under the Securities Act of 1933, as amended. Net proceeds from these issuances were used to repay a $49 million principal payment of ATXI’s 3.43% senior unsecured notes at maturity and to repay short-term debt.

Indenture Provisions and Other Covenants

Ameren Missouri’s and Ameren Illinois’ indentures and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions but would restrict the companies’ ability to issue bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges, dividend coverage ratios, and bonds and preferred stock issuable as of December 31, 2025, at an assumed interest rate of 7% and dividend rate of 8%.

Required Interest

Coverage Ratio(a)

Actual Interest
Coverage Ratio

Bonds Issuable(b)

Required Dividend

Coverage Ratio(c)

Actual Dividend
Coverage Ratio

Preferred Stock
Issuable

Ameren Missouri

>2.0

3.2

$3,777

>2.5

219.0

$3,702

Ameren Illinois

>2.0

6.6

9,482

>1.5

3.6

203

(d)

(a)Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.

(b)Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $895 million and $1,093 million at Ameren Missouri and Ameren Illinois, respectively.

(c)Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation.

(d)Preferred stock issuable is restricted by the amount of preferred stock that is currently authorized by Ameren Illinois’ articles of incorporation.

Ameren’s indenture does not require Ameren to comply with any quantitative financial covenants. The indenture does, however, include certain cross-default provisions. Specifically, either (1) the failure by Ameren to pay when due and upon expiration of any applicable grace period any portion of any Ameren indebtedness in excess of $25 million, or (2) the acceleration upon default of the maturity of any Ameren indebtedness in excess of $25 million under any indebtedness agreement, including borrowings under the Credit Agreements or the Ameren commercial paper program, constitutes a default under the indenture, unless such past due or accelerated debt is discharged or the acceleration is rescinded or annulled within a specified period.

Ameren Missouri and Ameren Illinois and certain other nonregistrant Ameren subsidiaries are subject to Section 305(a) of the Federal Power Act, which makes it unlawful for any officer or director of a public utility, as defined in the Federal Power Act, to participate in the making or paying of any dividend from any funds “properly included in capital account.” The FERC has consistently interpreted the provision to allow dividends to be paid as long as (1) the source of the dividends is clearly disclosed, (2) the dividends are not excessive, and (3) there is no self-dealing on the part of corporate officials. At a minimum, Ameren believes that dividends can be paid by its subsidiaries that are public utilities from net income and retained earnings. In addition, under Illinois law, Ameren Illinois and ATXI may not pay any dividend on their respective stock unless, among other things, their respective earnings and earned surplus are sufficient to declare and pay a dividend after provisions are made for reasonable and proper reserves, or unless Ameren Illinois or ATXI has specific authorization from the ICC.

Ameren Illinois’ articles of incorporation require dividend payments on its common stock to be based on ratios of common stock to total capitalization and other provisions related to certain operating expenses and accumulations of earned surplus. Ameren Illinois has made a commitment to the FERC to maintain a minimum 30% ratio of common stock equity to total capitalization. As of December 31, 2025, using the FERC-agreed upon calculation method, Ameren Illinois’ ratio of common stock equity to total capitalization was 55%.

ATXI’s note purchase agreements includes financial covenants that require ATXI not to permit at any time (1) debt to exceed 70% of total capitalization or (2) secured debt to exceed 10% of total assets.

At December 31, 2025, the Ameren Companies were in compliance with the provisions and covenants contained in their indentures and articles of incorporation, as applicable, and ATXI was in compliance with the provisions and covenants contained in its note purchase agreements. In order for the Ameren Companies to issue securities in the future, they will have to comply with all applicable requirements in effect at the time of any such issuances.

Off-Balance-Sheet Arrangements

At December 31, 2025, none of the Ameren Companies had any material off-balance-sheet financing arrangements, other than their investments in variable interest entities, letters of credit, and the forward sale agreements relating to common stock. See Note 1 – Summary of Significant Accounting Policies for further detail concerning variable interest entities.

Other Income, Net

12 Months Ended

Dec. 31, 2025

Other Nonoperating Income (Expense) [Abstract]

OTHER INCOME AND EXPENSES

OTHER INCOME, NET

The following table presents the components of “Other Income, Net” in the Ameren Companies’ statements of income for the years ended December 31, 2025, 2024, and 2023:


	2025		2024		2023
Ameren:
Other Income, Net
Allowance for equity funds used during construction	$	88	$	76	$	54
Other interest income	41		41		33
Non-service cost components of net periodic benefit income(a)	247		304		295
Miscellaneous income	17		9		7
Gain on extinguishment of debt(b)	8		16		—
Earnings (losses) related to equity method investments	(19)		(4)		1
Donations	(12)		(5)		(24)
Miscellaneous expense	(23)		(20)		(18)
Total Other Income, Net	$	347	$	417	$	348
Ameren Missouri:
Other Income, Net
Allowance for equity funds used during construction	$	56	$	58	$	30
Other interest income	9		8		11
Non-service cost components of net periodic benefit income(a)	126		139		97
Miscellaneous income	6		4		3
Donations	(7)		(2)		(2)
Miscellaneous expense	(10)		(11)		(9)
Total Other Income, Net	$	180	$	196	$	130
Ameren Illinois:
Other Income, Net
Allowance for equity funds used during construction	$	30	$	17	$	19
Other Interest income	32		32		21
Non-service cost components of net periodic benefit income	81		105		124
Miscellaneous income	9		4		4
Donations	(5)		(3)		(4)
Miscellaneous expense	(11)		(8)		(8)
Total Other Income, Net	$	136	$	147	$	156

(a)For the years ended December 31, 2025, 2024, and 2023, the non-service cost components of net periodic benefit income were adjusted by amounts deferred of $(53) million, $(41) million, and $27 million, respectively, due to a regulatory tracking mechanism for the difference between the level of such costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates. See Note 10 – Retirement Benefits for additional information.

(b)See Note 5 – Long-term Debt and Equity Financings for additional information on Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were accounted for as a debt extinguishment.

Derivative Financial Instruments

12 Months Ended

Dec. 31, 2025

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE FINANCIAL INSTRUMENTS

We use derivatives to manage the risk of changes in market prices for natural gas, power, and interest rates, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. Such price fluctuations may cause the following:

•an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;

•market values of natural gas that differ from the cost of this commodity in inventory;

•actual cash outlays for interest expense and the purchase of commodities that differ from anticipated cash outlays; and

•actual off-system sales revenues that differ from anticipated revenues.

The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.

All contracts considered to be derivative instruments are required to be recorded on the balance sheet at their fair values, unless the NPNS exception applies. See Note 8 – Fair Value Measurements for discussion of our methods of assessing the fair value of derivative instruments. Many of our physical contracts, such as our purchased power contracts, qualify for the NPNS exception to derivative accounting rules. The revenue or expense on NPNS contracts is recognized at the contract price upon physical delivery. The following disclosures exclude NPNS contracts and other non-derivative commodity contracts that are accounted for under the accrual method of accounting.

If we determine that a contract meets the definition of a derivative and is not eligible for the NPNS exception, we review the contract to determine whether the resulting gains or losses qualify for regulatory deferral. Derivative contracts that qualify for regulatory deferral are recorded at fair value, with changes in fair value recorded as regulatory assets or liabilities in the period in which the change occurs. We believe derivative losses and gains deferred as regulatory assets and liabilities are probable of recovery, or refund, through future rates charged to customers. Regulatory assets and liabilities are amortized to operating income as related losses and gains are reflected in rates charged to customers. Therefore, gains and losses on these derivatives have no effect on operating income. As of December 31, 2025 and 2024, all commodity contracts that met the definition of a derivative and were not eligible for the NPNS exception received regulatory deferral. Interest rate hedges entered into by Ameren (parent) and discussed below do not receive regulatory deferral and were included in accumulated OCI as Ameren (parent) is not a rate-regulated entity. The cash flows from our derivative financial instruments follow the cash flow classification of the hedged item.

Ameren (parent) entered into interest rate swaps to hedge a portion of its interest rate risk on cash flows related to certain forecasted debt issuances to occur in 2026 and 2027. The interest rate swaps are designated as cash flow hedges and the corresponding changes in fair value each period are initially recorded on the balance sheet in “Accumulated other comprehensive income” and reclassified into earnings when the debt is issued and the corresponding interest payments affect earnings during the debt term. As of December 31, 2025, and 2024, Ameren had interest rate swaps with notional amounts of $820 million and $140 million, respectively. Ameren recorded an unrealized gain, net of income taxes, on the change in fair value of interest rate swaps of $3 million and $3 million to "Accumulated other comprehensive income" for the years ended December 31, 2025 and 2024.

The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 2025 and 2024. As of December 31, 2025, these contracts extended through October 2029, October 2031, and May 2032 for fuel oils, natural gas, and power, respectively.


	Quantity (in millions, except as indicated)
	2025			2024
Commodity	Ameren Missouri	Ameren Illinois	Ameren	Ameren Missouri	Ameren Illinois	Ameren
Fuel oils (in gallons)	25	—	25	23	—	23
Natural gas (in mmbtu)	46	217	263	45	213	258
Power (in MWhs)	—	7	7	—	4	4

The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments because all qualify for regulatory deferral, as of December 31, 2025 and 2024:


		2025						2024
Commodity	Balance Sheet Location	Ameren Missouri		Ameren Illinois		Ameren			Ameren Missouri		Ameren Illinois		Ameren



Natural gas	Other current assets	$	1	$	1	$	2		$	2	$	2	$	4
	Other assets	—		3		3			2		4		6

Power	Other current assets	11		—		11			6		—		6



	Total assets	$	12	$	4	$	16		$	10	$	6	$	16

Fuel oils	Other current liabilities	$	3	$	—	$	3		$	2	$	—	$	2
	Other deferred credits and liabilities	2		—		2			2		—		2

Natural gas	Other current liabilities	5		21		26			5		22		27
	Other deferred credits and liabilities	5		11		16			6		13		19

Power	Other current liabilities	—		24		24			—		10		10
	Other deferred credits and liabilities	—		55		55			—		43		43



	Total liabilities	$	15	$	111	$	126		$	15	$	88	$	103

The Ameren Companies elect to present the fair value amounts of derivative assets and derivative liabilities subject to an enforceable master netting arrangement or similar agreement at the gross amounts on the balance sheet. However, if the gross amounts recognized on the balance sheet were netted with derivative instruments and cash collateral received or posted, the net amounts would not be materially different from the gross amounts at December 31, 2025 and 2024.

Credit Risk

In determining our concentrations of credit risk related to derivative instruments, we review our individual counterparties and categorize each counterparty into groupings according to the primary business in which each engages. As of December 31, 2025, if counterparty groups were to fail completely to perform on contracts, the Ameren Companies’ maximum exposure related to derivative assets would have been immaterial with or without consideration of the application of master netting arrangements or similar agreements and collateral held.

Certain of our derivative instruments contain collateral provisions tied to the Ameren Companies’ credit ratings. If our credit ratings were downgraded below investment grade, or if a counterparty with reasonable grounds for uncertainty regarding our ability to satisfy an obligation requested adequate assurance of performance, additional collateral postings might be required. The additional collateral required is the net liability position allowed under the master netting arrangements or similar agreements, assuming (1) the credit risk-related contingent features underlying these arrangements were triggered and (2) those counterparties with rights to do so requested collateral. As of December 31, 2025, the aggregate fair value of derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that counterparties could require were each immaterial to Ameren, Ameren Missouri, and Ameren Illinois.

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

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+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2025

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

Fair value is defined as the price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels:

Level 1 (quoted prices in active markets for identical assets or liabilities): Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives, cash and cash equivalents, and listed equity securities.

The market approach is used to measure the fair value of equity securities held in Ameren Missouri’s nuclear decommissioning trust fund. Equity securities in this fund are representative of the S&P 500 index, excluding securities of Ameren Corporation, owners and/or operators of nuclear power plants, and the trustee and investment managers. The S&P 500 index comprises stocks of large-capitalization companies.

Level 2 (significant other observable inputs): Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri’s nuclear decommissioning trust fund, including United States Treasury and agency securities, corporate bonds and other fixed-income securities, and certain over-the-counter derivative instruments, including natural gas and financial power transactions.

Fixed income securities are valued by using prices from independent industry-recognized data vendors who provide values that are either exchange-based or matrix-based. The fair value measurements of fixed-income securities classified as Level 2 are based on inputs other than quoted prices that are observable for the asset or liability. Examples are matrix pricing, market corroborated pricing, and inputs such as yield curves and indices.

Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the bid/ask spreads to the midpoints. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoints. The value of natural gas derivative contracts is based upon exchange closing prices without significant unobservable adjustments. The value of power derivative contracts is based upon exchange closing prices or the use of multiple forward prices provided by third parties.

Level 3 (significant other unobservable inputs): Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, such as certain internal assumptions, quotes or prices from outside sources not supported by a liquid market, or trend rates.

We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.

We consider nonperformance risk in our valuation of derivative instruments by analyzing our own credit standing and the credit standing of our counterparties, and by considering any credit enhancements (e.g., collateral). Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. No material gains or losses related to valuation adjustments for counterparty default risk were recorded at Ameren, Ameren Missouri, or Ameren Illinois in 2025, 2024, or 2023. At December 31, 2025 and 2024, the counterparty default risk valuation adjustment related to derivative contracts was immaterial for Ameren, Ameren Missouri, and Ameren Illinois.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2025 and 2024:


		December 31, 2025									December 31, 2024
		Level 1		Level 2		Level 3		Total			Level 1		Level 2		Level 3		Total
Assets:
Ameren Missouri
	Derivative assets – commodity contracts:

	Natural gas	—		1		—		1			—		4		—		4
	Power	—		—		11		11			—		—		6		6

	Total derivative assets – commodity contracts	$	—	$	1	$	11	$	12		$	—	$	4	$	6	$	10
	Nuclear decommissioning trust fund:

	Equity securities:
	U.S. large capitalization	$	1,028	$	—	$	—	$	1,028		$	911	$	—	$	—	$	911
	Debt securities:
	U.S. Treasury and agency securities	—		225		—		225			—		191		—		191
	Corporate bonds	—		177		—		177			—		145		—		145


	Other	—		84		—		84			—		86		—		86
	Total nuclear decommissioning trust fund	$	1,028	$	486	$	—	$	1,514	(a)	$	911	$	422	$	—	$	1,333	(a)
	Total Ameren Missouri	$	1,028	$	487	$	11	$	1,526		$	911	$	426	$	6	$	1,343
Ameren Illinois
	Derivative assets – commodity contracts:
	Natural gas	$	—	$	2	$	2	$	4		$	—	$	3	$	3	$	6

	Total Ameren Illinois	$	—	$	2	$	2	$	4		$	—	$	3	$	3	$	6
Ameren
	Derivative assets – commodity contracts(b)	$	—	$	3	$	13	$	16		$	—	$	7	$	9	$	16
	Nuclear decommissioning trust fund(c)	1,028		486		—		1,514		(a)	911		422		—		1,333		(a)
	Total Ameren	$	1,028	$	489	$	13	$	1,530		$	911	$	429	$	9	$	1,349
Liabilities:
Ameren Missouri
	Derivative liabilities – commodity contracts:
	Fuel oils	$	5	$	—	$	—	$	5		$	4	$	—	$	—	$	4
	Natural gas	—		10		—		10			—		11		—		11


	Total Ameren Missouri	$	5	$	10	$	—	$	15		$	4	$	11	$	—	$	15
Ameren Illinois
	Derivative liabilities – commodity contracts:
	Natural gas	$	1	$	28	$	3	$	32		$	1	$	28	$	6	$	35
	Power	—		13		66		79			—		—		53		53
	Total Ameren Illinois	$	1	$	41	$	69	$	111		$	1	$	28	$	59	$	88
Ameren
	Derivative liabilities – commodity contracts(b)	$	6	$	51	$	69	$	126		$	5	$	39	$	59	$	103

(a)Balance excludes $12 million and $9 million of cash and cash equivalents, receivables, payables, and accrued income, net for December 31, 2025 and 2024, respectively.

(b)See the Ameren Missouri and Ameren Illinois sections of the table for the fair value of Ameren’s derivative assets and liabilities by type of commodity.

(c)See the Ameren Missouri section of the table for Ameren’s nuclear decommissioning trust fund by investment type.

See Note 10 – Retirement Benefits for tables that set forth, by level within the fair value hierarchy, Ameren’s pension and postretirement plan assets as of December 31, 2025 and 2024.

Level 3 natural gas derivative contract assets and liabilities measured at fair value on a recurring basis were immaterial for all periods presented. The following table presents the fair value reconciliation of Level 3 power derivative contract assets and liabilities measured at fair value on a recurring basis for the years ended December 31, 2025 and 2024:


	2025						2024
	Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois		Ameren





















Beginning balance at January 1	$	6	$	(53)	$	(47)	$	4	$	(68)	$	(64)
Realized and unrealized gains (losses) included in regulatory assets/liabilities	29		(24)		5		12		(1)		11


Settlements	(24)		11		(13)		(10)		16		6


Ending balance at December 31	$	11	$	(66)	$	(55)	$	6	$	(53)	$	(47)
Change in unrealized gains (losses) related to assets/liabilities held at December 31	11		(23)		(12)		6		3		9

All gains or losses related to our Level 3 derivative commodity contracts are expected to be recovered or returned through customer rates; therefore, there is no impact to either net income or OCI resulting from changes in the fair value of these instruments.

The following table describes the valuation techniques and significant unobservable inputs utilized for the fair value of our Level 3 power derivative contract assets and liabilities as of December 31, 2025 and 2024:


		Fair Value							Weighted Average(b)
	Commodity	Assets		Liabilities		Valuation Technique(s)	Unobservable Input(a)	Range









2025	Power(c)	$	11	$	(66)	Discounted cash flow	Average forward peak and off-peak pricing – forwards/swaps ($/MWh)	33 – 72	43

							Nodal basis ($/MWh)	(9) – (2)	(5)














































2024	Power(c)	$	6	$	(53)	Discounted cash flow	Average forward peak and off-peak pricing – forwards/swaps ($/MWh)	32 – 69	45
							Nodal basis ($/MWh)	(8) – (2)	(5)

(a)Generally, significant increases (decreases) in these inputs in isolation would result in a significantly higher (lower) fair value measurement.

(b)Unobservable inputs were weighted by relative fair value.

(c)Valuations use visible forward prices adjusted for nodal-to-hub basis differentials.

The following table sets forth the carrying amount and, by level within the fair value hierarchy, the fair value of long-term debt (including current portion), disclosed, but not recorded, at fair value as of December 31, 2025 and 2024:


	Carrying Amount(a)		Fair Value
Long-Term Debt (Including Current Portion):				Level 2		Level 3			Total
	December 31, 2025




Ameren(b)	$	19,187		$	17,433	$	559	(c)	$	17,992






Ameren Missouri(d)	8,230			7,608		—			7,608





Ameren Illinois(d)	6,259			5,753		—			5,753
	December 31, 2024




Ameren(b)	$	17,579		$	15,395	$	538	(c)	$	15,933






Ameren Missouri(d)	7,745			6,926		—			6,926





Ameren Illinois(d)	5,852			5,243		—			5,243

(a)Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $136 million, $62 million, and $56 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2025. Included unamortized debt issuance costs, which were excluded from the fair value measurement, of $129 million, $62 million, and $51 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, as of December 31, 2024.

(b)Amount excludes Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were accounted for as a debt extinguishment. See Note 5 – Long-term Debt and Equity Financings for additional information.

(c)The Level 3 fair value amount consists of ATXI’s senior unsecured notes.

(d)Amount includes Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were repurchased by Ameren (parent) in 2025 and 2024.

The Ameren Companies’ carrying amounts of cash, cash equivalents, and restricted cash approximate fair value and are considered Level 1 in the fair value hierarchy. The Ameren Companies’ short-term borrowings approximate fair value because of the short-term nature of these instruments and are considered Level 2 in the fair value hierarchy.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Callaway Energy Center

12 Months Ended

Dec. 31, 2025

Nuclear Waste Matters [Abstract]

CALLAWAY ENERGY CENTER

Spent Nuclear Fuel

Under the Nuclear Waste Policy Act of 1982, as amended, the DOE is responsible for disposing of spent nuclear fuel from the Callaway

Energy Center and other commercial nuclear energy centers. As required by the act, Ameren Missouri and other utilities have entered into standard contracts with the DOE, which stated that the DOE would begin to dispose of spent nuclear fuel by 1998. However, the DOE failed to fulfill its disposal obligations, and Ameren Missouri and other nuclear energy center owners sued the DOE to recover costs incurred for ongoing storage of their spent fuel. Ameren Missouri’s lawsuit against the DOE resulted in a settlement agreement that provides for annual reimbursement of additional spent fuel storage and related costs. Ameren Missouri received immaterial reimbursements from the DOE in the years ended December 31, 2025, 2024, and 2023. Ameren Missouri will continue to apply for reimbursement from the DOE for allowable costs associated with the ongoing storage of spent fuel. The DOE’s delay in carrying out its obligation to dispose of spent nuclear fuel from the Callaway Energy Center is not expected to adversely affect the continued operations of the energy center.

Decommissioning

Electric rates charged to customers provide for the recovery of the Callaway Energy Center’s decommissioning costs, which include decontamination, dismantling, and site restoration costs, over the expected life of the nuclear energy center. Amounts collected from customers are deposited into the external nuclear decommissioning trust fund to provide for the Callaway Energy Center’s decommissioning. It is assumed that the Callaway Energy Center site will be decommissioned after its retirement through the immediate dismantlement method and removed from service. The Callaway Energy Center’s operating license currently expires in 2044. Ameren and Ameren Missouri have recorded an ARO for the Callaway Energy Center decommissioning costs at fair value. Annual decommissioning costs of $7 million have historically been included in the costs used to establish electric rates for Ameren Missouri’s customers. Every three years, the MoPSC requires Ameren Missouri to file an updated cost study and funding analysis for decommissioning its Callaway Energy Center. An updated cost study and funding analysis was filed with the MoPSC in December 2023 and reflected within the ARO. In May 2025, the MoPSC issued an order that approved a non-unanimous stipulation and agreement between Ameren Missouri and the MoPSC staff that reduced annual customer contributions for funding the Callaway Energy Center decommissioning costs from $7 million to zero, as the trust fund level exceeded the estimated present value of future decommissioning costs at the time of the agreement. This MoPSC order removed Ameren Missouri’s funding obligation effective in June 2025.

Ameren and Ameren Missouri have classified the investments in debt and equity securities that are held in the nuclear decommissioning trust fund as available for sale, and have recorded all such investments at their fair market value at December 31, 2025 and 2024. Investments in the nuclear decommissioning trust fund have a target allocation of 60% to 70% in equity securities, with the balance invested in debt securities.

The fair value of the trust fund for Ameren Missouri’s Callaway Energy Center is reported as “Nuclear decommissioning trust fund” in Ameren’s and Ameren Missouri’s balance sheets. This amount is legally restricted and may be used only to fund the costs of nuclear decommissioning. Changes in the fair value of the trust fund are recorded as an increase or decrease to the nuclear decommissioning trust fund, with an offsetting adjustment to the regulatory liability related to AROs. This reporting is consistent with the method used to account for the decommissioning costs recovered in rates. See Note 2 – Rate and Regulatory Matters for the regulatory liability recorded at December 31, 2025. If the assumed return on trust assets is not earned, Ameren Missouri believes that it is probable that any additional funding requirements resulting from such earnings deficiency will be recovered in customer rates.

The following table presents proceeds from the sales and maturities of investments in Ameren Missouri’s nuclear decommissioning trust fund and the gross realized gains and losses resulting from those sales for the years ended December 31, 2025, 2024, and 2023:


	2025		2024		2023
Proceeds from sales and maturities	$	416	$	564	$	240
Gross realized gains	37		44		6
Gross realized losses	7		28		11

The following table presents the cost and fair value of investments in debt and equity securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund at December 31, 2025 and 2024:


Security Type	Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
2025
Debt securities	$	488	$	7	$	9	$	486
Equity securities	179		858		9		1,028
Cash and cash equivalents	8		—		—		8
Other(a)	4		—		—		4
Total	$	679	$	865	$	18	$	1,526
2024
Debt securities	$	437	$	2	$	17	$	422
Equity securities	179		740		8		911
Cash and cash equivalents	10		—		—		10
Other(a)	(1)		—		—		(1)
Total	$	625	$	742	$	25	$	1,342

(a)Represents net receivables and payables relating to pending securities sales, interest, and securities purchases.

The following table presents the costs and fair values of investments in debt securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund according to their contractual maturities at December 31, 2025:


	Cost		Fair Value
Less than 5 years	$	207	$	208
5 years to 10 years	139		141
Due after 10 years	142		137
Total	$	488	$	486

Insurance

The following table presents insurance coverage at Ameren Missouri’s Callaway Energy Center at January 1, 2026:


Type and Source of Coverage	Most Recent Renewal Date	Maximum Coverages			Maximum Assessments for Single Incidents
Public liability and nuclear worker liability:
American Nuclear Insurers	January 1, 2026	$	500		$	—
Pool participation	(a)	15,763		(a)	166		(b)
		$	16,263	(c)	$	166
Property damage:
NEIL and EMANI	April 1, 2025	$	3,200	(d)	$	22	(e)
Accidental outage:
NEIL	April 1, 2025	$	490	(f)	$	9	(e)

(a)Provided through mandatory participation in an industrywide retrospective premium assessment program. The maximum coverage available is dependent on the number of United States commercial reactors participating in the program.

(b)Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $500 million in the event of an incident at any licensed United States commercial reactor, payable at $25 million per year.

(c)Limit of liability for each incident under the Price-Anderson liability provisions of the Atomic Energy Act of 1954, as amended. This limit is subject to change to account for the effects of inflation and changes in the number of licensed power reactors.

(d)NEIL provides $2.7 billion in property damage, stabilization, decontamination, and premature decommissioning insurance for radiation events and $0.7 billion in property damage insurance for nonradiation events. EMANI provides $490 million in property damage insurance for both radiation and nonradiation events.

(e)All NEIL-insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.

(f)Accidental outage insurance provides for lost sales in the event of a prolonged accidental outage. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first 12 weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Nonradiation events are limited to $291 million.

The Price-Anderson Act is a federal law that limits the liability for claims from an incident involving any licensed United States commercial nuclear energy center. The limit is based on the number of licensed reactors. The limit of liability and the maximum potential annual payments are adjusted at least every five years for inflation to reflect changes in the Consumer Price Index. The most recent five-year inflationary adjustment became effective in October 2023. Owners of a nuclear reactor cover this exposure through a combination of private insurance and mandatory participation in a financial protection pool, as established by the Price-Anderson Act.

Losses resulting from terrorist attacks on nuclear facilities insured by NEIL are subject to industrywide aggregates, such that terrorist acts against one or more commercial nuclear power plants within a stated time period would be treated as a single event, and the owners of the nuclear power plants would share the limit of liability. NEIL policies have an aggregate limit of $3.2 billion within a 12-month period for radiation events, or $1.8 billion for events not involving radiation contamination, resulting from terrorist attacks. The EMANI policies are not subject to industrywide aggregates in the event of terrorist attacks on nuclear facilities.

If losses from a nuclear incident at the Callaway Energy Center exceed the limits of, or are not covered by insurance, or if coverage is unavailable, Ameren Missouri is at risk for any uninsured losses. If a serious nuclear incident were to occur, it could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, or liquidity.

Retirement Benefits

12 Months Ended

Dec. 31, 2025

Retirement Benefits [Abstract]

RETIREMENT BENEFITS

The primary objective of the Ameren pension and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren has defined benefit pension plans covering substantially all of its employees and has a postretirement benefit plan covering non-union employees hired before October 2015 and union employees hired before January 2020. Ameren Missouri and Ameren Illinois each participate in Ameren’s single-employer pension and other postretirement plans. All non-union employees participate in a cash balance pension plan. Ameren Missouri union employees hired after June 2013, and Ameren Illinois union employees hired after mid-October 2012, participate in a cash balance pension plan. Ameren uses a measurement date of December 31 for its pension and postretirement benefit plans. Ameren’s qualified pension plan is the Ameren Retirement Plan. Ameren’s other postretirement plan is the Ameren Retiree Welfare Benefit Plan. Ameren also has an unfunded nonqualified pension plan, the Ameren Supplemental Retirement Plan, which is available to provide certain non-union employees and retirees with a supplemental benefit when their qualified pension plan benefits are capped in compliance with Internal Revenue Code limitations. Only Ameren subsidiaries participate in the plans listed above.

Ameren’s pension and other postretirement benefit plans were overfunded by $954 million and $734 million in the aggregate as of December 31, 2025 and 2024, respectively. These net assets are recorded in “Pension and other postretirement benefits,” “Other current liabilities,” and “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet. The increase in the overfunded pension and postretirement benefit plans during 2025 was primarily the result of an increase in the actual return on plan assets of the pension and postretirement trusts and a 5-basis-point increase in the pension discount rate used to determine the present value of the obligation. The overfunded pension and other postretirement benefit plans also resulted in regulatory liabilities on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets.

The following table presents the net benefit liability/(asset) recorded on the balance sheets as of December 31, 2025 and 2024:


	2025		2024
Ameren(a)	$	(954)	$	(734)
Ameren Missouri(a)	(261)		(201)
Ameren Illinois(a)	(563)		(438)

(a)Liabilities associated with pension and other postretirement benefits are recorded in “Other current liabilities” and “Other deferred credits and liabilities” on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets.

In December 2025, Ameren, completed a contract transfer transaction with a third-party insurance company that transferred approximately $240 million of plan assets and plan obligations of the Ameren Retirement Plan, associated with approximately 4,200 former Ameren Missouri, Ameren Illinois, and Ameren Services employees, that will assume future and full responsibility to fund and administer their benefit payments. The transaction is designed to reduce potential volatility with the pension plan assets and liabilities and administrative costs. There was no change to the pension benefits for any participants because of the transfer. The transaction was funded by pension plan assets and resulted in an actuarial gain of $15 million, which will be amortized in net periodic benefit cost (income) over 10 years through the actuarial (gain) loss component beginning in 2026.

Ameren recognizes the overfunded and underfunded status of its pension and postretirement plans as an asset or a liability on its consolidated balance sheet, with offsetting entries to accumulated OCI and regulatory assets or liabilities. The following table presents the funded status of Ameren’s pension and postretirement benefit plans as of December 31, 2025 and 2024. It also provides the amounts included in regulatory assets or liabilities and accumulated OCI at December 31, 2025 and 2024, that have not been recognized in net periodic benefit costs.


	2025				2024
	Pension Benefits			Postretirement Benefits	Pension Benefits			Postretirement Benefits
Accumulated benefit obligation at end of year	$	3,773	$	(a)	$	3,962	$	(a)
Change in benefit obligation:
Net benefit obligation at beginning of year	$	4,134	$	807	$	4,258	$	856
Service cost	82			10	88			12
Interest cost	234			45	222			44

Participant contributions	—			7	—			7
Actuarial (gain) loss	28		(b)	5	(143)			(51)
Contract transfer(c)	(240)			—	—			—
Benefits paid	(299)			(68)	(291)			(61)


Net benefit obligation at end of year	3,939			806	4,134			807
Change in plan assets:
Fair value of plan assets at beginning of year	4,182			1,493	4,272			1,393
Actual return on plan assets	456			162	193			150
Employer contributions	3			3	8			4


Participant contributions	—			7	—			7
Contract transfer(c)	(240)			—	—			—

Benefits paid	(299)			(68)	(291)			(61)
Fair value of plan assets at end of year	4,102			1,597	4,182			1,493
Funded status – surplus	(163)			(791)	(48)			(686)
Accrued benefit asset at December 31	$	(163)	$	(791)	$	(48)	$	(686)
Amounts recognized in the balance sheet consist of:
Noncurrent asset	$	(186)	$	(791)	$	(71)	$	(686)
Current liability(d)	2			—	2			—
Noncurrent liability(e)	21			—	21			—
Net asset recognized	$	(163)	$	(791)	$	(48)	$	(686)
Amounts recognized in regulatory assets or liabilities consist of:
Net actuarial (gain) loss	$	(45)	$	(404)	$	42	$	(379)
Prior service credit	—			(18)	—			(21)

Amounts recognized in accumulated OCI (pretax) consist of:
Net actuarial (gain) loss	22			(7)	26			(7)

Total	$	(23)	$	(429)	$	68	$	(407)

(a)Not applicable.

(b)Includes a $15 million gain from the contract transfer of defined benefit pension obligations and related plan assets to a third-party insurance company in December 2025 as described above.

(c)Represents the contract transfer of defined benefit pension obligations and related plan assets to a third-party insurance company in December 2025 as described above.

(d)Included in “Other current liabilities” on Ameren’s consolidated balance sheet.

(e)Included in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet.

The following table presents the assumptions used to determine our benefit obligations at December 31, 2025 and 2024:


	Pension Benefits				Postretirement Benefits
	2025		2024		2025		2024
Discount rate at measurement date	5.75	%	5.70	%	5.70	%	5.70	%
Increase in future compensation	4.00		4.00		4.00		4.00
Cash balance pension plan interest crediting rate	5.50		5.50		(a)		(a)
Medical cost trend rate (initial)(b)	(a)		(a)		(c)		(c)
Medical cost trend rate (ultimate)(b)	(a)		(a)		5.00		5.00

(a)Not applicable.

(b)Initial and ultimate medical cost trend rate for certain Medicare-eligible participants was 2.50% at December 31, 2025 and 2024.

(c)Initial medical cost trend rates of 7.50% and 7.00% for both pre-Medicare plan participants and post-Medicare plan participants at December 31, 2025 and 2024, respectively, trend down to the ultimate rate by 2036 and 2033, respectively, with a 3.00% upward adjustment to the post-Medicare trend rate in 2024.

Ameren determines discount rate assumptions by identifying a theoretical settlement portfolio of high-quality corporate bonds sufficient to provide for a plan’s projected benefit payments. The settlement portfolio of bonds is selected from a pool of high-quality corporate bonds. A single discount rate is then determined; that rate results in a discounted value of the plan’s benefit payments that equates to the market value of the selected bonds. In 2025, Ameren elected to continue to use the Society of Actuaries mortality table and the Society of Actuaries 2020 Mortality Improvement Scale.

Funding

Pension benefits are based on the employees’ years of service, age, and compensation. Ameren’s pension plans are funded in compliance with income tax regulations, federal funding requirements, and other regulatory requirements. As a result, Ameren expects to fund its pension plans at a level equal to the greater of the pension cost or the legally required minimum contribution. Based on its assumptions at December 31, 2025, its investment performance in 2025, and its pension funding policy, Ameren expects to make annual contributions of approximately $45 million to $50 million in each of the next five years, with aggregate estimated contributions of $240 million. Ameren Missouri and Ameren Illinois estimate that their portion of the future funding requirements will be 35% and 45%, respectively. These estimated contributions may change based on actual investment performance, changes in interest rates, changes in our assumptions, changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense.

The following table presents the cash contributions made to our defined benefit retirement plans and to our postretirement plan during 2025, 2024, and 2023:


	Pension Benefits						Postretirement Benefits
	2025		2024		2023		2025		2024		2023
Ameren Missouri	$	1	$	1	$	1	$	1	$	2	$	2
Ameren Illinois	1		1		2		1		1		1
Ameren Services	1		6		1		1		1		—
Ameren	$	3	$	8	$	4	$	3	$	4	$	3

Investment Strategy and Policies

Ameren manages plan assets in accordance with the “prudent investor” guidelines contained in ERISA. The investment committee, which includes members of senior management, approves and implements investment strategy and asset allocation guidelines for the plan assets. The investment committee’s goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable; and second, to maximize total return on plan assets and to minimize expense volatility consistent with its tolerance for risk. Ameren delegates the task of investment management to specialists in each asset class. As appropriate, Ameren provides each investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines.

The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we reviewed the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns and for the effect of expenses paid from plan assets. Ameren will use an expected return on plan assets for its pension and postretirement plan assets of 6.75% in 2026.

Ameren’s investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate), duration, market capitalization, country, style (growth or value), and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee’s strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk.

Ameren’s investment committee developed and implemented a liability hedging investment strategy for its qualified pension plan designed to reduce interest rate risk as part of an objective for its long-term investment strategy. The plan invests in derivative instruments mainly consisting of interest rate futures intended to extend the duration of the pension plan assets so that the assets are more closely aligned with the duration of the liabilities. In addition, part of Ameren’s investment strategy includes participation in a securities lending program, which allows it to lend eligible securities to third party borrowers. All loans are collateralized by at least 103% of the loaned asset’s market value and the collateral is invested in the form of cash, government obligations, and U.S. agency obligations. Ameren’s fair value of securities loaned was $517 million and $454 million as of December 31, 2025 and 2024, respectively. Cash and securities obtained as collateral exceeded the fair value of the securities loaned as of December 31, 2025 and 2024.

The following table presents our target allocations and our pension and postretirement plans’ asset categories as of December 31, 2025 and 2024:


Asset Category	Target Allocation 2025	Percentage of Plan Assets at December 31,
		2025			2024
Pension Plan:
Cash and cash equivalents	0% – 5%	3	%		3	%
Equity securities:
U.S. large-capitalization	10% – 20%	15	%		16	%
U.S. small- and mid-capitalization	3% – 13%	9	%		9	%
Global	10% – 20%	16	%		15	%
International	4% – 14%	7	%		9	%
Total equity	42% – 52%	47	%		49	%
Debt securities	32% – 42%	34	%	(a)	35	%	(a)
Diversified credit	6% – 16%	10	%		8	%
Real estate	0% – 10%	6	%		5	%
Private equity	0% – 5%	—	%		(b)
Total		100	%		100	%
Postretirement Plans:
Cash and cash equivalents	0% – 7%	2	%		2	%
Equity securities:
U.S. large-capitalization	23% – 33%	33	%		33	%
U.S. small- and mid-capitalization	3% – 13%	7	%		8	%
Global	9% – 19%	13	%		13	%
International	5% – 15%	8	%		8	%
Total equity	55% – 65%	61	%		62	%
Debt securities	33% – 43%	37	%		36	%
Total		100	%		100	%

(a)Includes interest rate futures derivative instruments.

(b)Less than 1% of plan assets.

In general, the United States large-capitalization equity investments are passively managed or indexed, whereas the international, global, United States small-capitalization, and United States mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed-income vehicles. Debt security investments in high-yield securities and non-United-States-dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Diversified credit investments include but are not limited to, sub-investment grade rated bonds and loans, securitized credit, and emerging market debt. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. In addition to the derivative investments included in the liability hedging investment strategy described above, Ameren’s investment committee also allows investment managers to use derivatives, such as index futures, foreign exchange futures, and options, in certain situations to increase or to reduce market exposure in an efficient and timely manner.

Fair Value Measurements of Plan Assets

Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 2025. Fair value is defined as the price that would be received for an asset in the principal or most advantageous market for the asset in an orderly transaction between market participants on the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the measurement date or, if that is not a business day, on the last business day before that date. Securities traded in over-the-counter markets are valued by quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Investments measured under NAV as a practical expedient are based on the fair values of the underlying assets provided by the funds and their administrators. The fair value of real estate investments is based on NAV; it is determined by annual appraisal reports prepared by an independent real estate appraiser. Investments measured at NAV often provide for daily, monthly, or quarterly redemptions with 60 or less days of notice depending on the fund. For some funds, redemption may also require approval from the fund’s board of directors. Derivative contracts are valued at fair value, as determined by the investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension plans’ assets measured at fair value and NAV as of December 31, 2025 and 2024:


	December 31, 2025								December 31, 2024
	Level 1		Level 2		NAV		Total			Level 1		Level 2		NAV		Total
Cash and cash equivalents	$	—	$	—	$	96	$	96		$	—	$	—	$	75	$	75
Equity securities:
U.S. large-capitalization	—		—		648		648			—		—		689		689
U.S. small- and mid-capitalization	382		—		—		382			375		—		—		375
International	120		—		203		323			182		—		226		408
Global	—		—		671		671			—		—		680		680
Debt securities:
Corporate bonds	—		418		—		418			—		463		—		463
Municipal bonds	—		36		—		36			—		36		—		36
U.S. Treasury and agency securities	—		1,016		—		1,016			—		1,032		—		1,032
Diversified credit	—		—		456		456			—		—		344		344
Other	(10)		7		—		(3)			(17)		11		—		(6)
Real estate	—		—		243		243			—		—		233		233

Total	$	492	$	1,477	$	2,317	$	4,286		$	540	$	1,542	$	2,247	$	4,329
Less: Medical benefit assets(a)							(222)									(200)
Plus: Net receivables (payables)(b)							38									53
Fair value of pension plans’ assets							$	4,102								$	4,182

(a)Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation.

(b)Net of receivables related to pending securities sales and payables related to pending securities purchases.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plans’ assets measured at fair value and NAV as of December 31, 2025 and 2024:


	December 31, 2025								December 31, 2024
	Level 1		Level 2		NAV		Total			Level 1		Level 2		NAV		Total
Cash and cash equivalents	$	18	$	—	$	—	$	18		$	25	$	—	$	—	$	25
Equity securities:
U.S. large-capitalization	353		—		106		459			332		—		91		423
U.S. small- and mid-capitalization	100		—		—		100			106		—		—		106
International	56		—		59		115			54		—		52		106
Global	—		—		178		178			—		—		165		165

Debt securities:

Municipal bonds	—		187		—		187			—		173		—		173


Other	—		—		315		315			—		—		293		293
Total	$	527	$	187	$	658	$	1,372		$	517	$	173	$	601	$	1,291
Plus: Medical benefit assets(a)							222									200
Plus: Net receivables(b)							3									2
Fair value of postretirement benefit plans’ assets							$	1,597								$	1,493

(a)Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

(b)Net of receivables related to pending securities sales and payables related to pending securities purchases.

Net Periodic Benefit Cost

The following table presents the components of the net periodic benefit cost (income) of Ameren’s pension and postretirement benefit plans during 2025, 2024, and 2023:


	Pension Benefits						Postretirement Benefits
	2025		2024		2023		2025		2024		2023
Service cost(a)	$	82	$	88	$	79	$	10	$	12	$	12
Non-service cost components:
Interest cost	234		222		221		45		44		45
Expected return on plan assets(b)	(303)		(327)		(333)		(94)		(93)		(91)
Amortization of(b):

Prior service cost (credit)	—		—		—		(4)		(4)		(4)
Actuarial (gain)	(34)		(67)		(115)		(38)		(38)		(45)


Total non-service cost components(c)	$	(103)	$	(172)	$	(227)	$	(91)	$	(91)	$	(95)
Net periodic benefit cost (income)(d)	$	(21)	$	(84)	$	(148)	$	(81)	$	(79)	$	(83)

(a)Service cost, net of capitalization, is reflected in “Operating Expenses - Other operations and maintenance” on Ameren’s statement of income.

(b)Prior service cost (credit) is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. Net actuarial gains or losses subject to amortization are amortized on a straight-line basis over 10 years. Expected return on plan assets is based on a market-related value of assets that recognizes asset (gains) losses over 4 years.

(c)Non-service cost components are reflected in “Other Income, Net” on Ameren’s consolidated statement of income. See Note 6 – Other Income, Net for additional information.

(d)Does not include the impact of the tracker for the difference between the level of pension and postretirement benefit costs (income) incurred by Ameren Missouri under GAAP and the level of such costs included in rates.

The Ameren Companies are responsible for their share of the pension and postretirement benefit costs (income). The following table presents the pension and postretirement benefit costs (income) incurred for the years ended December 31, 2025, 2024, and 2023:


	Pension Costs						Postretirement Costs
	2025		2024		2023		2025		2024		2023
Ameren Missouri(a)	$	(14)	$	(44)	$	(76)	$	(28)	$	(27)	$	(30)
Ameren Illinois	(4)		(34)		(62)		(53)		(52)		(54)
Other	(3)		(6)		(10)		—		—		1
Ameren	$	(21)	$	(84)	$	(148)	$	(81)	$	(79)	$	(83)

(a)Does not include the impact of the tracker for the difference between the level of pension and postretirement benefit costs (income) incurred by Ameren Missouri under GAAP and the level of such costs included in customer rates.

The expected pension and postretirement benefit payments from qualified trust and company funds, which reflect expected future service, as of December 31, 2025, are as follows:


	Pension Benefits				Postretirement Benefits
	Paid from Qualified Trust Funds		Paid from Company Funds		Paid from Qualified Trust Funds		Paid from Company Funds
2026	$	262	$	2	$	59	$	3
2027	267		2		59		3
2028	271		2		59		3
2029	275		2		58		3
2030	279		2		58		3
2031 – 2035	1,424		14		288		13

The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 2025, 2024, and 2023:


	Pension Benefits						Postretirement Benefits
	2025		2024		2023		2025		2024		2023
Discount rate at measurement date	5.70	%	5.25	%	5.55	%	5.70	%	5.25	%	5.55	%
Expected return on plan assets	6.75		6.75		6.75		6.75		6.75		6.75
Increase in future compensation(a)	4.00		3.50		3.50		4.00		3.50		3.50
Cash balance pension plan interest crediting rate(b)	5.50		5.50		5.00		(c)		(c)		(c)
Medical cost trend rate (initial)(d)	(c)		(c)		(c)		(e)		(f)		(g)
Medical cost trend rate (ultimate)(d)	(c)		(c)		(c)		5.00		5.00		5.00

(a)Increase in future compensation is 4.00% for the year ended December 31, 2025, 4.00% for 2024 and 3.50% thereafter for the year ended December 31, 2024, and 4.50% for 2023, 4.00% for 2024, and 3.50% thereafter for the year ended December 31, 2023.

(b)Cash balance pension plan interest crediting rate is 5.20% for 2025 and 5.50% thereafter for the year ended December 31, 2025, was 6.42% for 2024, and 5.50% thereafter for the year ended December 31, 2024, and 5.50% for 2023 and 2024, and 5.00% thereafter for the year ended December 31, 2023.

(c)Not applicable.

(d)Initial and ultimate medical cost trend rate for certain Medicare-eligible participants is 2.50% for the years ended December 31, 2025, 2024, and 2023.

(e)Initial medical cost trend rates of 7.00% for pre-Medicare plan participants and 7.00% for post-Medicare plan participants trend down to the ultimate rate by 2033 with a 3.00% upward adjustment to the post-Medicare trend rate in 2025.

(f)Initial medical cost trend rates of 6.93% for pre-Medicare plan participants and 6.50% for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025.

(g)Initial medical cost trend rates of 7.25% for pre-Medicare plan participants and 6.75% for post-Medicare plan participants trend down to the ultimate rate by 2030, with a 3.00% upward adjustment to the post-Medicare trend rate in 2025.

Other

Ameren sponsors a 401(k) plan for eligible employees. The Ameren 401(k) plan covered all eligible Ameren employees at December 31, 2025. The plan allows employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matches a percentage of the employee contributions up to certain limits. The following table presents the portion of the matching contribution to the Ameren 401(k) plan attributable to each of the Ameren Companies for the years ended December 31, 2025, 2024, and 2023:


	2025		2024		2023
Ameren Missouri	$	26	$	26	$	27
Ameren Illinois	22		22		21
Other	1		1		1
Ameren	$	49	$	49	$	49

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (o)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (p)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (q)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 60
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480266/715-60-50-3

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480126/715-20-S99-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 70
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480794/715-70-50-1

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (l)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/715/tableOfContent

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (r)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

+ Details

Stock-Based Compensation

12 Months Ended

Dec. 31, 2025

Share-Based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION

The 2022 Omnibus Incentive Compensation Plan is Ameren’s long-term incentive plan available for eligible employees and directors. It provides for a maximum of 8.8 million common shares to be available for grant to eligible employees and directors. At December 31, 2025, there were 7.3 million common shares remaining for grant. Awards may be restricted stock, restricted stock units, stock options (incentive stock options and nonqualified stock options), stock appreciation rights, performance awards, cash-based awards and other stock-based awards. Ameren used newly issued shares to fulfill its stock-based compensation obligations for 2025, 2024, and 2023, and intends to use newly issued shares to fulfill its stock-based compensation obligations for 2026.

The following table summarizes Ameren’s outstanding performance share unit and restricted stock unit activity for the year ended December 31, 2025:


	Performance Share Units – Market Condition(a)			Performance Share Units – Performance Condition(b)			Restricted Stock Units
	Share Units	Weighted-average Fair Value per Share Unit		Share Units	Weighted-average Fair Value per Share Unit		Stock Units	Weighted-average Fair Value per Stock Unit
Outstanding at January 1, 2025(c)	808,950	$	77.73	120,997	$	79.09	395,520	$	79.73
Granted	245,464	123.19		40,408	96.66		132,931	97.33
Forfeitures	(80,469)	87.56		(13,337)	82.09		(47,305)	83.77
Dividend equivalents(d)	22,947	87.13		3,452	82.34		10,968	82.72
Vested and distributed	(217,017)	92.75		(34,980)	87.85		(119,601)	87.95

Outstanding at December 31, 2025(c)	779,875	$	87.12	116,540	$	82.31	372,513	$	82.95

(a)The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the specified market conditions. Compensation cost on nonforfeited awards is recognized regardless of whether Ameren achieves the specified market conditions.

(b)The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the performance goals. Compensation cost is recognized ratably over the requisite service period only for awards for which it is probable that the performance condition will be satisfied.

(c)Outstanding awards include awards that vest on a pro-rata basis due to attainment of retirement eligibility by employees, but have not yet been distributed. In these cases, the pro-rata basis awards have not yet been distributed as the entire performance period has not been completed. The number of shares issued for retirement-eligible employees will vary depending on actual performance over the three-year performance period.

(d)Dividend equivalents represent the right to receive shares measured by the dividend payable with respect to the corresponding number of outstanding share units. Dividend equivalents will accrue and be reinvested in additional share units throughout the performance period.

Performance Share Units – Market Condition

A market condition performance share unit vests and entitles an employee to receive shares of Ameren common stock (plus accumulated dividends) if, at the end of the three-year performance period, certain specified market conditions have been met and if the individual remains employed by Ameren through the required vesting period. The vesting period for share units awarded extends beyond the three-year performance period to the payout date, which is approximately 38 months after the grant date. In the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis over the three-year performance period. The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the specified market conditions.

The fair value of each share unit is based on a Monte Carlo simulation. The Monte Carlo simulation is used to estimate expected share payout based on Ameren’s TSR for a three-year performance period relative to the designated peer group beginning January 1st of the award year. The simulation can produce a greater or lesser fair value for the share unit than the applicable closing common share price because it includes the weighted payout scenarios in which an increase or decrease in the share price has occurred and/or in which the payout is above 100% due to Ameren’s projected TSR performance. The key assumptions used to calculate fair value also include a three-year risk-free rate, Ameren’s common stock volatility, and volatility for the peer group. The following table presents the fair value of each share unit along with the significant assumptions used to calculate the fair value of each share unit for the years ended December 31, 2025, 2024, and 2023:


	2025	2024	2023
Fair value of share units awarded	$123.19	$56.73	$91.07

Three-year risk-free rate	4.23%	4.25%	4.19%
Ameren’s common stock volatility(a)	21%	21%	26%
Volatility range for the peer group(a)	19% – 24%	19% – 23%	24% – 32%

(a)Based on a historical period that is equal to the remaining term of the performance period as of the grant date.

In addition to the market condition performance share units described above, there are an immaterial number of market condition performance share units with different vesting conditions and target payout percentages.

Performance Share Units – Performance Condition

A performance condition share unit vests and entitles an employee to receive shares of Ameren common stock (plus accumulated dividends) if, at the end of the three-year performance period, Ameren has met the specified performance condition and if the individual remains employed by Ameren through the required vesting period. The vesting period for share units awarded extends beyond the three-year performance period to the payout date, which is approximately 38 months after the grant date. In the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis over the three-year performance period. The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual performance conditions achieved. The specified performance condition in each award year is based on Ameren’s clean energy transition. The grant-date fair value for an individual outcome of a performance condition is determined by Ameren’s closing common share price on the grant date.

Restricted Stock Units

Restricted stock units vest and entitle an employee to receive shares of Ameren common stock (plus accumulated dividends) if the individual remains employed with Ameren through the payment date of the awards. In the event of a participant’s death or retirement at age 55 or older with five years or more of service, awards vest on a pro-rata basis. The payout date of the awards is approximately 38 months after the grant date. The fair value of each restricted stock unit is determined by Ameren’s closing common share price on the grant date.

Stock-Based Compensation Expense

The following table presents the stock-based compensation expense for the years ended December 31, 2025, 2024, and 2023:


	2025		2024		2023
Ameren Missouri	$	8	$	8	$	6
Ameren Illinois	4		4		4
Other(a)	16		16		16
Ameren	28		28		26
Less: Income tax benefit	7		7		7
Stock-based compensation expense, net	$	21	$	21	$	19

(a)Represents compensation expense for employees of Ameren Services. These amounts are not included in the Ameren Missouri and Ameren Illinois amounts above.

Ameren settled performance share units and restricted stock units of $38 million, $24 million, and $60 million for the years ended December 31, 2025, 2024, and 2023, respectively. There were no significant stock-based compensation costs capitalized during the years ended December 31, 2025, 2024, and 2023. As of December 31, 2025, total compensation cost of $43 million related to outstanding awards not yet recognized is expected to be recognized over a weighted-average period of 23 months.

For the years ended December 31, 2025, 2024, and 2023, excess tax benefits (deficiencies) associated with the settlement of stock-based compensation awards reduced (increased) income tax expense by $1 million, $(1) million, and $6 million, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

INCOME TAXES

IRA

The IRA was enacted in August 2022, and includes various income tax provisions, among other things. The law extends federal production and investment tax credits for projects beginning construction through 2024 and allows for a 10% adder to the production and investment tax credits for siting projects at existing energy communities as defined in the law, which includes sites previously used for coal-fired generation. The law also creates production and investment tax credits for projects beginning construction after 2024. The production and investment tax credits will apply to renewable energy production and investments, along with certain nuclear energy production. See the OBBBA below for additional information on revisions to the production and investment tax credits. The law allows for transferability, subject to revisions made by the OBBBA discussed below, to an unrelated party for cash of up to 100% of certain tax credits generated after 2022. In addition, the law imposes a 15% minimum tax on adjusted financial statement income, as defined in the law, for corporations whose average annual adjusted financial statement income exceeds $1 billion for three consecutive preceding tax years. Once a corporation exceeds this three-year average annual adjusted financial statement income threshold, it will be subject to the minimum tax for all future tax years. Additional regulations, interpretations, amendments, or technical corrections to or in connection with the IRA have been and are expected to be issued by the IRS or United States Department of Treasury, which may impact the timing of when the 15% minimum tax becomes applicable for Ameren.

OBBBA

The OBBBA was enacted in July 2025 and includes various income tax provisions, among other things. The OBBBA modified provisions of the IRA related to production and investment tax credits. The new law maintains production and investment tax credits for solar and wind projects that begin construction within one year of the OBBBA’s enactment and are placed in-service by the end of 2030. Projects that begin construction after one year from enactment of the OBBBA but are placed in service by the end of 2027 also remain eligible. The law provides investment tax credits for battery storage projects that begin construction by the end of 2033, which phase out by the end of 2035. Renewable energy projects that begin construction in 2026 and beyond that use a certain threshold percentage of materials from prohibited foreign entities, as defined in the OBBBA, are not eligible for the tax credits. Production tax credits associated with nuclear generation remain unchanged from the IRA and phase out by the end of 2032. Furthermore, the new law continues to allow for transferability of the production and investment tax credits to an unrelated party for cash but such credits are restricted from being transferred to specified foreign entities, as defined in the OBBBA. Ameren did not have any material impacts on its results of operations, financial position, and liquidity in 2025 related to the OBBBA. Implementation of the OBBBA provisions is subject to additional guidance, regulations, interpretations, amendments, or technical corrections that may be issued by the IRS or United States Department of Treasury. Ameren will continue to monitor and assess any impacts related to the OBBBA.

The following table presents the principal reasons for the difference between the effective income tax expense and rate and the federal statutory corporate income tax expense and rate for the years ended December 31, 2025, 2024, and 2023:


	2025				2024				2023
	Amount		Effective Tax Rate		Amount		Effective Tax Rate		Amount		Effective Tax Rate
Ameren
Federal statutory corporate income tax expense and rate	$	335	21	%	$	267	21	%	$	282	21	%
State and local taxes, net of federal income tax(a)	74		5		61		5		64		5


Tax credits
Renewable energy tax credits(b)	(61)		(4)		(117)		(9)		(52)		(4)

Other	(3)		—		(7)		—		(6)		—
Changes in valuation allowances	—		—		(4)		—		5		—
Nontaxable or nondeductible items	(2)		—		1		—		(5)		—



Other adjustments
Amortization of excess deferred income taxes(c)	(107)		(7)		(112)		(9)		(98)		(8)
Revaluation of excess deferred income taxes(d)	(86)		(5)		—		—		—		—
Depreciation differences	(14)		(1)		(8)		(1)		(7)		—
Other	—		—		2		—		—		—
Effective income tax expense and rate	$	136	9	%	$	83	7	%	$	183	14	%
Ameren Missouri
Federal statutory corporate income tax expense and rate	$	166	21	%	$	100	21	%	$	113	21	%
State and local taxes, net of federal income tax(a)	21		3		13		3		14		3


Tax credits
Renewable energy tax credits(b)	(61)		(8)		(113)		(24)		(49)		(10)

Other	(3)		—		(4)		(1)		(5)		(1)

Nontaxable or nondeductible items	1		—		1		—		(1)		—



Other adjustments
Amortization of excess deferred income taxes(c)	(75)		(10)		(79)		(17)		(80)		(15)
Depreciation differences	(6)		(1)		(5)		—		—		—
Effective income tax expense (benefit) and rate	$	43	5	%	(87)		(18)	%	$	(8)	(2)	%
Ameren Illinois
Federal statutory corporate income tax expense and rate	$	187	21	%	$	171	21	%	$	172	21	%
State and local taxes, net of federal income tax(a)	66		7		62		7		61		7


Tax credits
Renewable energy tax credits	—		—		(3)		—		—		—

Other	(1)		—		(2)		—		(1)		—

Nontaxable or nondeductible items	(1)		—		—		—		(1)		—



Other adjustments
Amortization of excess deferred income taxes(c)	(31)		(3)		(32)		(4)		(17)		(2)
Revaluation of excess deferred income taxes(d)	(61)		(7)		—		—		—		—
Depreciation differences	(9)		(1)		(3)		—		(5)		—
Other	3		—		—		—		—		—
Effective income tax expense and rate	$	153	17	%	$	193	24	%	$	209	26	%

(a)State taxes in Missouri and Illinois made up the majority of the tax effect in this category for Ameren, Ameren Missouri, and Ameren Illinois.

(b)The benefit of the credits associated with Missouri renewable energy standard compliance is refunded to customers through the RESRAM. The benefit of the credits associated with the production and investment tax credit tracker will be refunded to customers based on MoPSC approval in a regulatory rate review.

(c)Reflects the amortization of a regulatory liability resulting from the revaluation of accumulated deferred income taxes subject to regulatory ratemaking, which are being refunded to customers.

(d)In 2024, the IRS issued a series of private letter rulings to another taxpayer, which provided guidance on applying IRS normalization rules to the calculation of tax benefits applicable to the ratemaking treatment related to net operating loss carryforwards. The rulings concluded that, for ratemaking purposes, net operating loss carryforwards should be reflected on a separate company basis and should not be reduced by payments received for the utilization of losses by other affiliates under a tax allocation agreement. In 2025, the FERC issued an order reflecting implementation of the rules for the other taxpayer who had a similar fact pattern as Ameren Illinois and ATXI. In addition, in 2025, the ICC issued orders in Ameren Illinois’ 2024 electric distribution service revenue requirement reconciliation adjustment proceeding and in its January 2025 natural gas rate review addressing the impacts of the private letter rulings. Accordingly, in 2025, Ameren and Ameren Illinois decreased income tax expense by $86 million and $61 million, respectively, to reflect the revaluation of excess deferred income tax regulatory liabilities resulting from TCJA for FERC-regulated and ICC-regulated jurisdictions pursuant to IRS guidance and recent FERC and ICC orders.

The following table presents the components of income tax expense (benefit) for the years ended December 31, 2025, 2024, and 2023:


	Ameren Missouri		Ameren Illinois		Other		Ameren
2025
Current taxes:
Federal	$	(140)	$	64	$	(41)	$	(117)
State	(2)		19		(17)		—
Deferred taxes:
Federal	233		38		(2)		269
State	38		63		1		102
Amortization of excess deferred income taxes	(75)		(31)		(1)		(107)
Amortization of deferred investment tax credits	(11)		—		—		(11)
Total income tax expense (benefit)	$	43	$	153	$	(60)	$	136
2024
Current taxes:
Federal	$	(55)	$	5	$	7	$	(43)
State	(3)		—		2		(1)
Deferred taxes:
Federal	45		144		(12)		177
State	8		76		(19)		65
Amortization of excess deferred income taxes	(79)		(32)		(1)		(112)
Amortization of deferred investment tax credits	(3)		—		—		(3)
Total income tax expense (benefit)	$	(87)	$	193	$	(23)	$	83
2023
Current taxes:
Federal	$	(37)	$	27	$	(37)	$	(47)
State	1		5		(5)		1
Deferred taxes:
Federal	102		123		35		260
State	9		71		(10)		70
Amortization of excess deferred income taxes	(80)		(17)		(1)		(98)
Amortization of deferred investment tax credits	(3)		—		—		(3)
Total income tax expense (benefit)	$	(8)	$	209	$	(18)	$	183

The following table presents the accumulated deferred income tax assets and liabilities recorded as a result of temporary differences and accumulated deferred production and investment tax credits at December 31, 2025 and 2024:


	Ameren Missouri		Ameren Illinois		Other		Ameren
2025
Accumulated deferred income taxes, net liability (asset):
Plant-related	$	2,652	$	2,416	$	244	$	5,312
Regulatory assets and liabilities, net	(179)		(130)		(16)		(325)
Deferred employee benefit costs	(2)		89		(16)		71
Tax carryforwards	(190)		(45)		(108)		(343)
Other	161		21		21		203
Total net accumulated deferred income tax liabilities (assets)	2,442		2,351		125		4,918
Accumulated deferred investment tax credits	260		3		—		263
Accumulated deferred income taxes and investment tax credits	$	2,702	$	2,354	$	125	$	5,181
2024
Accumulated deferred income taxes, net liability (asset):
Plant-related	$	2,429	$	2,250	$	261	$	4,940
Regulatory assets and liabilities, net	(193)		(170)		(22)		(385)
Deferred employee benefit costs	(25)		77		(25)		27
Tax carryforwards	(355)		(45)		(103)		(503)
Other	131		28		3		162
Total net accumulated deferred income tax liabilities (assets)	1,987		2,140		114		4,241
Accumulated deferred investment tax credits	230		3		—		233
Accumulated deferred income taxes and investment tax credits	$	2,217	$	2,143	$	114	$	4,474

The following table presents the components of accumulated deferred income tax assets relating to net operating loss carryforwards and tax credit carryforwards at December 31, 2025 and 2024:


	Ameren Missouri		Ameren Illinois		Other		Ameren
2025
Net operating loss carryforwards:
Federal(a)	$	53	$	—	$	24	$	77
State(b)	9		34		45		88
Total net operating loss carryforwards	$	62	$	34	$	69	$	165
Tax credit carryforwards:
Federal(c)	$	128	$	9	$	39	$	176
State(d)	—		2		—		2

Total tax credit carryforwards	$	128	$	11	$	39	$	178



2024
Net operating loss carryforwards:
Federal	$	—	$	—	$	30	$	30
State	—		34		29		63
Total net operating loss carryforwards	$	—	$	34	$	59	$	93
Tax credit carryforwards:
Federal	$	355	$	9	$	44	$	408
State	—		2		—		2

Total tax credit carryforwards	$	355	$	11	$	44	$	410

(a)No expiration date.

(b)Will expire between 2039 and 2047.

(c)Will expire between 2032 and 2045.

(d)Will expire between 2026 and 2030.

The following table presents the total income taxes paid, net of refunds, including production and investment tax credit sale proceeds, for the years ended December 31, 2025, 2024, and 2023:


	Ameren Missouri(a)						Ameren Illinois(a)							Ameren
	2025		2024		2023			2025		2024		2023			2025		2024		2023
Federal(b)	$	(350)	$	(131)	$	(24)		$	79	$	(25)	$	76		$	(309)	$	(92)	$	(37)
State
Illinois	—		—		—			39		(21)		26			34		(12)		28
Missouri	(9)		(5)		5			—		—		—			(37)		12		(15)
Total taxes paid	$	(359)	$	(136)	$	(19)		$	118	$	(46)	$	102		$	(312)	$	(92)	$	(24)

(a)Amounts represent income tax paid, net of refunds, to Ameren (parent), pursuant to the tax allocation agreement. See Note 1 – Summary of Significant Accounting Policies – Income Taxes for additional information.

(b)Includes production and investment tax credit sale proceeds for Ameren and Ameren Missouri of $314 million, $95 million, and $49 million for the years ended December 31, 2025, 2024, and 2023, respectively.

Uncertain Tax Positions

As of December 31, 2025 and 2024, the Ameren Companies did not record any uncertain tax positions.

Ameren is a part of the IRS’s compliance assurance process program, which involves real-time review of compliance with federal income tax law. State income tax returns are generally subject to examination for a period of three years after filing. The state impact of any federal changes remains subject to examination by various states for up to one year after formal notification to the states. Ameren’s federal tax return for the 2024 tax year is open, but, at the time of this filing, the Ameren Companies do not have material income tax issues under examination, administrative appeals, or litigation.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 740
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477617/942-740-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
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-Paragraph 1
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-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147478822/944-740-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Related Party Transactions

12 Months Ended

Dec. 31, 2025

RELATED PARTY TRANSACTIONS

RELATED-PARTY TRANSACTIONS

In the normal course of business, Ameren Missouri and Ameren Illinois engage in affiliate transactions. These transactions primarily consist of natural gas and power purchases and sales, services received or rendered, and borrowings and lendings. Transactions between Ameren’s subsidiaries are reported as affiliate transactions on their individual financial statements, but those transactions are eliminated in consolidation for Ameren’s consolidated financial statements. Below are the material related-party agreements.

Electric Power Supply Agreements

Ameren Illinois must acquire capacity and energy sufficient to meet its obligations to customers. Ameren Illinois uses periodic RFP processes, administered by the IPA and approved by the ICC, to contract capacity and energy on behalf of its customers. Ameren Missouri participates in the RFP process and has been a winning supplier for certain periods.

Capacity Supply Agreements

In procurement events in 2021, Ameren Missouri contracted to supply a portion of Ameren Illinois’ capacity requirements for $2 million from June 2022 through May 2023.

Energy Product Agreements

Based on the outcome of an IPA-administered procurement event in 2021, Ameren Missouri and Ameren Illinois have entered into an energy product agreement by which Ameren Missouri agreed to sell, and Ameren Illinois agreed to purchase, 136,000 MWhs at an average price of $37 per MWh from January 2022 through September 2023.

Interconnection Agreements

Ameren Missouri and Ameren Illinois are parties to an interconnection agreement that governs the connection of their respective transmission lines and other facilities used for the distribution of power. These agreements have no contractual expiration date, but may be terminated by either party with three years’ notice.

Ameren Missouri and ATXI are parties to an interconnection agreement that governs the connection of the High Prairie Energy Center to an ATXI transmission line that allows Ameren Missouri to distribute power generated from the High Prairie Energy Center.

Ameren Missouri and Ameren Illinois are parties to interconnection agreements that govern the connection of the Cass County and Boomtown energy centers to Ameren Illinois transmission lines that allows Ameren Missouri to distribute power generated from the Cass County and Boomtown energy centers.

Support Services Agreements

Ameren Services provides support services to its affiliates. The costs of support services including wages, employee benefits, professional services, and other expenses, are based on, or are an allocation of, actual costs incurred. The support services agreement can be terminated at any time by the mutual agreement of Ameren Services and that affiliate or by either party with 60 days’ notice before the end of a calendar year.

In addition, Ameren Missouri and Ameren Illinois provide affiliates with access to their facilities for administrative purposes and with use of other assets. The costs of the rent and facility services and other assets are based on, or are an allocation of, actual costs incurred.

Ameren Missouri and Ameren Illinois also provide storm-related and miscellaneous support services to each other on an as-needed basis.

Ameren Missouri and Ameren Illinois had long-term receivables included in “Other assets” from Ameren Services of $36 million and $38 million, respectively, as of December 31, 2025, and $29 million and $32 million, respectively, as of December 31, 2024, related to Ameren Services’ allocated portion of Ameren’s pension and postretirement benefit plans.

Transmission Services

Ameren Missouri and Ameren Illinois each receives transmission services from ATXI for their respective retail loads.

Electric Transmission Maintenance and Construction Agreements

ATXI entered into separate agreements with Ameren Missouri and Ameren Illinois in which Ameren Missouri or Ameren Illinois, as applicable, may perform certain maintenance and construction services related to ATXI’s electric transmission assets.

Money Pool

See Note 4 – Short-term Debt and Liquidity for a discussion of affiliate borrowing arrangements.

Long-Term Debt, Net - Related Parties

In November 2024, December 2024, and June 2025, Ameren (parent) purchased senior secured notes and first mortgage bonds issued by Ameren Missouri, and first mortgage bonds issued by Ameren Illinois. See Note 5 – Long-term Debt and Equity Financings for additional information.

Tax Allocation Agreement

See Note 1 – Summary of Significant Accounting Policies for a discussion of the tax allocation agreement. The following table presents the affiliate balances related to income taxes for Ameren Missouri and Ameren Illinois as of December 31, 2025 and 2024:


	2025				2024
	Ameren Missouri		Ameren Illinois		Ameren Missouri		Ameren Illinois
Income taxes payable to parent(a)	$	—	$	4	$	—	$	32
Income taxes receivable from parent(b)	3		7		28		—

(a)Included in “Accounts payable – affiliates” on the balance sheet.

(b)Included in “Accounts receivable – affiliates” on the balance sheet.

Capital Contributions

The following table presents cash capital contributions received from Ameren (parent) by Ameren Missouri and Ameren Illinois for the years ended December 31, 2025, 2024, and 2023:


	2025		2024		2023
Ameren Missouri(a)	$	28	$	476	$	—
Ameren Illinois(a)	2		36		91

(a)Includes capital contributions made as a result of the tax allocation agreement.

Effects of Related-party Transactions on the Statement of Income

The following table presents the impact on Ameren Missouri and Ameren Illinois of related-party transactions for the years ended December 31, 2025, 2024, and 2023. It is based primarily on the agreements discussed above and the money pool arrangements discussed in Note 4 – Short-term Debt and Liquidity.


Agreement	Income Statement Line Item			Ameren Missouri		Ameren Illinois
Ameren Missouri power supply agreements	Operating Revenues	2025	$	—	$	(a)
with Ameren Illinois		2024		—		(a)
		2023		2		(a)
Ameren Missouri and Ameren Illinois	Operating Revenues	2025		31		1
rent and facility services		2024		31		1
		2023		32		(b)
Ameren Illinois interconnection agreement	Operating Revenues	2025		(a)		1
with Ameren Missouri		2024		(a)		(b)
		2023		(a)		—
Ameren Missouri and Ameren Illinois	Operating Revenues	2025		1		5
miscellaneous support services		2024		2		2
		2023		(b)		2



Total Operating Revenues		2025	$	32	$	7
		2024		33		3
		2023		34		2
Ameren Illinois power supply	Purchased Power	2025	$	(a)	$	—
agreements with Ameren Missouri		2024		(a)		—
		2023		(a)		2
Ameren Missouri interconnection agreement	Purchased Power	2025		1		(a)
with Ameren Illinois		2024		(b)		(a)
		2023		—		(a)
Ameren Missouri and Ameren Illinois	Purchased Power	2025		10		2
transmission services from ATXI		2024		9		2
		2023		2		1
Total Purchased Power		2025	$	11	$	2
		2024		9		2
		2023		2		3
Ameren Missouri and Ameren Illinois	Other Operations and	2025	$	(b)	$	3
rent and facility services	Maintenance	2024		1		1
		2023		(b)		3
Ameren Services support services	Other Operations and	2025		177		164
agreement	Maintenance	2024		169		158
		2023		148		138
Total Other Operations and		2025	$	177	$	167
Maintenance Expenses		2024		170		159
		2023		148		141
Money pool borrowings (advances)	(Interest Charges)	2025	$	(1)	$	1
	Other Income, Net	2024		(4)		(b)
		2023		(b)		(b)
Long-term debt, net - related parties	(Interest Charges)	2025	$	(3)	$	(b)
		2024		(b)		(b)
		2023		(a)		(a)

(a)Not applicable.

(b)Amount less than $1 million.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

Commitments And Contingencies	12 Months Ended
Commitments And Contingencies	Dec. 31, 2025
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES We are involved in legal, tax, and regulatory proceedings before various courts, regulatory commissions, authorities, and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in the notes to our financial statements, will not have a material adverse effect on our results of operations, financial position, or liquidity. See also Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 9 – Callaway Energy Center, Note 13 – Related-party Transactions, and Note 15 – Supplemental Information in this report. Environmental Matters Our electric generation, transmission, and distribution and natural gas distribution and storage operations must comply with a variety of statutes and regulations relating to the protection of the environment and human health and safety, including permitting programs implemented by federal, state, and local authorities. Such environmental laws regulate air emissions; protect water bodies; regulate the handling and disposal of hazardous substances and waste materials; establish siting and land use requirements; and protect against ecological impacts. Complex and lengthy processes are required to obtain and renew approvals, permits, and licenses for new, existing, or modified energy-related facilities. Additionally, the use and handling of various chemicals and hazardous materials require release prevention plans and emergency response procedures. Environmental regulations impact the electric utility industry, and compliance obligations could be costly for Ameren Missouri, which operates coal-fired and natural gas-fired energy centers. Compliance obligations under the Clean Air Act stem from a variety of programs including the NSPS, the MATS, emission allowance programs, the CSAPR, and the National Ambient Air Quality Standards, which are subject to periodic review for certain pollutants. Collectively, these regulations cover a variety of pollutants, such as SO2, particulate matter, NOx, mercury, toxic metals and acid gases, and CO2 emissions, although the scope of covered pollutants can change. To the extent our operations impact surface water bodies, including wetlands, the Clean Water Act requires permitting as well as evaluation of the ecological and biological impact of those operations. Implementation of requirements under the Clean Air Act and the Clean Water Act typically occurs through the issuance of permits by state regulators or resource agencies, and capital expenditures associated with compliance could be significant. The management and disposal of coal ash from our coal-fired energy centers must comply with federal regulations known as the CCR Rule issued under the Resource Conservation and Recovery Act and require the closure of surface impoundments at our coal-fired energy centers along with groundwater monitoring requirements and the implementations of corrective measures if necessary. The combined effects of compliance with existing and future environmental regulations could result in significant capital expenditures, increased operating costs, and the potential for closure or alteration of operations at some of Ameren Missouri’s energy centers. Ameren and Ameren Missouri expect that such compliance costs would be recoverable through rates, subject to MoPSC prudence review, but the timing of costs and their recovery could be subject to regulatory lag. Additionally, Ameren Missouri’s wind generation facilities may be subject to operating restrictions to limit the impact on protected species. Since 2021, Ameren Missouri’s High Prairie Energy Center has curtailed nighttime operations from April through October to limit impacts on protected species during the critical biological season. Ameren Missouri does not anticipate these operating curtailments will have a material impact on its results of operations, financial position, or liquidity. In 2026, Ameren Missouri plans to apply for a new federal permit to operate the High Prairie Energy Center which, if approved, would reduce restrictions limiting the energy center’s impact on protected species for 30 years. The application will also propose various mitigation measures and operating curtailments based on Ameren Missouri’s assessment of mitigation technologies. Ameren Missouri’s current permit expires in May 2027. Due to various actions taken by the EPA, which are discussed below, Ameren and Ameren Missouri have revised capital expenditure estimates necessary to comply with environmental regulations to a range of $70 million to $100 million from 2026 through 2030. Additional capital expenditures beyond 2030 could be required. This estimate includes surface impoundment closure and corrective action measures required by the 2015 CCR Rule and modifications to cooling water intake structures at existing power plants under Clean Water Act rules in place prior to 2024, all of which are discussed below. The EPA could review and revise compliance requirements. In addition to planned retirements of coal-fired energy centers that were included in Ameren Missouri’s 2025 Change to the 2023 PRP and with respect to the Illinois emissions standards discussed below, Ameren Missouri’s current plan for compliance with existing air emission regulations includes burning low-sulfur coal and optimizing existing air pollution control equipment. Accordingly, the actual amount of capital expenditures required to comply with existing environmental regulations could vary from the above estimates because of uncertainty as to revisions to regulatory requirements by the EPA and/or state regulators and their timing and varying cost of potential compliance strategies, among other things. The following sections describe the significant environmental statutes and regulations and environmental enforcement and remediation matters that affect or could affect our operations. The EPA could ultimately revise all or part of such federal regulations. Clean Air Act Federal and state laws, including the CSAPR, regulate emissions of SO2 and NOx through the reduction of emissions at their source and the use and retirement of emission allowances available for state budgets. In 2022, the EPA proposed the Good Neighbor Rule to reduce the transport of ozone from power plants by reducing the amount of CSAPR NOx allowances available for compliance. The EPA subsequently rejected state implementation plans proposed by Missouri and other states to comply with the Good Neighbor Rule and issued a federal implementation plan. The disapprovals for some state implementation plans, including Missouri’s, were stayed by multiple appellate courts, and in 2024, the United States Supreme Court issued a stay of the federal implementation plan. In January 2026, the EPA issued a proposed rule to reconsider the Good Neighbor Rule. Ameren Missouri complies with the current CSAPR requirements by minimizing emissions with low-sulfur coal, operation of two scrubbers at its Sioux Energy Center, and optimization of existing NOx air pollution control equipment. If a final rule is issued similar to the proposed rule, Ameren Missouri would not expect additional NOx controls at its coal-fired energy centers to be necessary. CO2 Emissions Standards In April 2024, the EPA issued a final rule that sets CO2 emission standards for existing coal-fired and new natural gas-fired power plants based on the emissions expected from adoption of carbon capture technology and/or natural gas co-firing for coal-fired power plants and carbon capture technology for new natural gas-fired power plants. Affected power plants are required to comply with the rule through a phased-in approach or retire. In June 2025, the EPA issued a proposed rule to repeal all greenhouse gas emissions standards for fossil fuel-fired power plants, including the April 2024 rule. The EPA expects to issue a final rule in the first half of 2026. In addition, in February 2026, the EPA issued a final rule rescinding its 2009 Endangerment Finding for greenhouse gas emissions, which was the basis for implementing greenhouse gas emissions standards. Ameren and Ameren Missouri are assessing the final rule and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity. MATS In April 2024, the EPA revised the MATS by establishing a more stringent standard for emissions of particulate matter, as well as requiring the use of continuous emissions monitoring systems. In April 2025, the presidential administration issued a proclamation through which it granted owners of coal-fired energy centers, including Ameren Missouri, a two-year extension of the compliance deadline. As such, the compliance deadline for the Labadie and Sioux energy centers is now set for July 2029. In June 2025, the EPA issued a proposed rule to repeal the April 2024 revisions to the MATS. The EPA expects to issue a final rule in 2026. NSPS In January 2026, the EPA issued a final rule that established NOx emission standards for several subcategories of natural gas-fired stationary CTs that began construction after December 13, 2024, based on size, utilization, design efficiency, and fuel type. Ameren and Ameren Missouri are assessing the final rule and, at this time, cannot predict the final impacts on their results of operations, financial position, and liquidity. NSR and Clean Air Act Litigation In December 2024, the United States District Court for the Eastern District of Missouri issued an order resolving all outstanding claims related to a complaint filed against Ameren Missouri by the United States Department of Justice that alleged certain projects performed at the coal-fired Rush Island Energy Center violated provisions of the Clean Air Act. The order requires Ameren Missouri to fund a program to provide electric buses and charging stations to schools within its service territory and a program to provide air purifiers to eligible electric residential customers. Ameren and Ameren Missouri each had liabilities of $36 million in “Other current liabilities” on their consolidated balance sheets as of December 31, 2025 and had liabilities of $40 million and $24 million in “Other current liabilities” and “Other deferred credits and liabilities”, respectively, on their consolidated balance sheets as of December 31, 2024. In addition, Ameren and Ameren Missouri each recorded charges of $59 million in “Other operations and maintenance” on their consolidated statements of income in 2024 related to the cost of these programs. Clean Water Act All of Ameren Missouri’s coal-fired and nuclear energy centers are subject to Clean Water Act requirements to identify measures for reducing the number of aquatic organisms impinged on a power plant’s cooling water intake screens or entrained through the plant’s cooling water system. Cooling water intake requirements are implemented by state regulators through the permit renewal process of each power plant’s water discharge permit. Permits for Ameren Missouri’s coal-fired and nuclear energy centers have been issued or are in the process of renewal. CCR Management The EPA’s 2015 CCR Rule establishes requirements for the management and disposal of CCR from coal-fired power plants and has resulted in the closure of surface impoundments at Ameren Missouri’s energy centers, with closures of surface impoundments in process at its Sioux Energy Center and retired Meramec Energy Center. Ameren Missouri plans to substantially complete the closures of remaining surface impoundments by the end of 2026. Ameren Missouri’s CCR management compliance plan includes installation of groundwater monitoring equipment and groundwater treatment facilities. In April 2024, the EPA revised the CCR Rule to impose groundwater monitoring, and corrective action, closure, and post-closure requirements on certain active and inactive CCR surface impoundments and disposal units not previously included in the 2015 CCR Rule. Ameren and Ameren Missouri had AROs of $56 million associated with CCR storage facilities recorded on their respective balance sheets as of December 31, 2025. This amount includes an immaterial incremental ARO related to the 2024 CCR Rule, which may be revised as additional site studies are performed. The EPA could reconsider aspects of the 2015 and 2024 CCR rules. Ameren and Ameren Missouri are monitoring the ongoing legal challenges and regulatory developments but, at this time, cannot predict the final impacts of the 2024 CCR Rule on their results of operations, financial position, and liquidity. Remediation The Ameren Companies are involved in a number of remediation actions to clean up sites impacted by the use or disposal of materials containing hazardous substances. Federal and state laws can require responsible parties to fund remediation regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site. As of December 31, 2025, Ameren Illinois has remediated the majority of the 44 former MGP sites in Illinois with an estimated remaining obligation primarily related to three of these former MGP sites at $45 million to $90 million. Ameren and Ameren Illinois recorded a liability of $45 million to represent the estimated minimum obligation for these sites, as no other amount within the range was a better estimate. Ameren and Ameren Illinois cannot estimate the completion dates of the estimated remaining obligation due to site accessibility, among other things. The scope of the remediation activities at these former MGP sites may increase as remediation efforts continue. Considerable uncertainty remains in these estimates because many site-specific factors can influence the actual costs, including unanticipated underground structures, the degree to which groundwater is impacted, regulatory changes, local ordinances, and site accessibility. The actual costs and timing of completion may vary substantially from these estimates. The ICC allows Ameren Illinois to recover MGP remediation and related litigation costs from its electric and natural gas utility customers through environmental cost riders that are subject to annual prudence reviews by the ICC. Our operations or those of our predecessor companies involve the use of, disposal of, and, in appropriate circumstances, the cleanup of substances regulated under environmental laws. Such historical practices may result in future environmental commitments, including additional or more stringent cleanup standards. We are unable to determine whether such historical practices will affect our results of operations, financial position, or liquidity. Illinois Emission Standards Currently as required by the CEJA, Ameren Missouri's natural gas-fired energy centers in Illinois are subject to annual limits on emissions, including CO2 and NOx. Further reductions to emissions limits will become effective between 2030 and 2040, resulting in the possible closure of the Venice Energy Center by the end of 2029. The reductions could also limit the operations of Ameren Missouri's four other natural gas-fired energy centers located in the state of Illinois and will result in their closure by 2040. These energy centers are utilized to support peak loads. Subject to conditions in the CEJA, these energy centers may be allowed to exceed the emissions limits in order to maintain reliability of electric utility service.

Supplemental Information

12 Months Ended

Dec. 31, 2025

Supplemental Information [Abstract]

Supplemental Information

SUPPLEMENTAL INFORMATION

Cash, Cash Equivalents, and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows as of December 31, 2025 and 2024:


	December 31, 2025						December 31, 2024
	Ameren		Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois
“Cash and cash equivalents”	$	13	$	6	$	3	$	7	$	—	$	—
Restricted cash included in “Other current assets”	63		54		5		15		7		6
Restricted cash included in “Other assets”	336		—		336		296		—		296
Restricted cash included in “Nuclear decommissioning trust fund”	8		8		—		10		10		—
Total cash, cash equivalents, and restricted cash	$	420	$	68	$	344	$	328	$	17	$	302

Restricted cash included in “Other current assets” represents funds held by an irrevocable Voluntary Employee Beneficiary Association (VEBA) trust, which provides health care benefits for active employees on Ameren’s, Ameren Missouri’s, and Ameren Illinois’ balance sheets, funds held in an escrow account for programs established as a result of a 2024 court order resolving outstanding claims in the NSR and Clean Air Act litigation on Ameren’s and Ameren Missouri’s balance sheets, and AMF’s restricted cash for payments for securitized utility tariff bonds on Ameren’s and Ameren Missouri’s balance sheets. Restricted cash included in “Other assets” on Ameren’s and Ameren Illinois’ balance sheets primarily represents amounts collected under a cost recovery rider restricted for use in the procurement of renewable energy credits and amounts in a trust fund restricted for the use of funding certain asbestos-related claims.

Accounts Receivable

“Accounts receivable – trade” on Ameren’s and Ameren Illinois’ balance sheets include certain receivables purchased at a discount from alternative retail electric suppliers that elect to participate in the utility consolidated billing program. At December 31, 2025 and 2024, “Other current liabilities” on Ameren’s and Ameren Illinois’ balance sheets included payables for purchased receivables of $47 million and $43 million, respectively.

The following table provides a reconciliation of the beginning and ending amount of the allowance for doubtful accounts for the years ended December 31, 2025 and 2024:


	December 31, 2025						December 31, 2024
	Ameren Missouri		Ameren Illinois(a)		Ameren			Ameren Missouri		Ameren Illinois(a)		Ameren
Beginning balance at January 1	$	12	$	18	$	30		$	12	$	18	$	30
Bad debt expense	17		34		51			11		28		39
Charged to other accounts(b)	—		7		7			—		8		8
Net write-offs	(12)		(37)		(49)			(11)		(36)		(47)
Ending balance at December 31	$	17	$	22	$	39		$	12	$	18	$	30

(a)Ameren Illinois has rate-adjustment mechanisms that allow it to recover the difference between its actual net bad debt write-offs under GAAP, including those associated with receivables purchased from alternative retail electric suppliers, and the amount of net bad debt write-offs included in its base rates.

(b)Amounts associated with the allowance for doubtful accounts related to receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act.

Leases

Ameren and Ameren Missouri have lease agreements primarily relating to rail cars and land related to solar generation facilities. The land leases are related to the Cass County, Boomtown, and Huck Finn energy centers. Rail cars are leased for the transportation of coal to its energy centers. For rail car leases, we account for the lease and non-lease components as a single lease component, and for the land leases related to solar generation projects, we account for the components separately for each agreement. Certain of the land leases related to the acquisitions of the Cass County, Boomtown, and Huck Finn energy centers have options to renew or terminate those leases. Termination and renewal options are not expected to be exercised and are not included in any of the lease measurements used to record the leased assets and liabilities in the tables below.

The following table provides supplemental balance sheet information related to operating leases as of December 31, 2025 and 2024:


	December 31, 2025						December 31, 2024
	Ameren			Ameren Missouri			Ameren			Ameren Missouri
Other assets	$	76		$	70		$	72		$	69
Other current liabilities	3			2			5			4
Other deferred credits and liabilities	73			68			67			65
Weighted average remaining operating lease term	28 years			29 years			29 years			30 years
Weighted average discount rate(a)	5.3		%	5.3		%	5.3		%	5.3		%

(a)As an implicit rate is not readily determinable under most of our lease agreements, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use an implicit rate when readily determinable.

The following table presents Ameren’s and Ameren Missouri’s remaining maturities of operating lease liabilities as of December 31, 2025:


	Ameren		Ameren Missouri
2026	$	6	$	5
2027	6		5
2028	6		5
2029	6		5
2030	5		4
Thereafter	129		127
Total lease payments	$	158	$	151
Less imputed interest	82		81
Total	$	76	$	70

Inventories

The following table presents the components of inventories for each of the Ameren Companies at December 31, 2025 and 2024:


	December 31, 2025						December 31, 2024
	Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois		Ameren
Fuel(a)	$	101	$	—	$	101	$	113	$	—	$	113
Natural gas stored underground	10		88		98		9		82		91
Materials, supplies, and other	381		190		575		392		162		558
Total inventories	$	492	$	278	$	774	$	514	$	244	$	762

(a)Consists of coal, oil, and propane.

Asset Retirement Obligations

The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the years ended December 31, 2025 and 2024:


	December 31, 2025									December 31, 2024
	Ameren Missouri			Ameren Illinois			Ameren			Ameren Missouri			Ameren Illinois			Ameren
Beginning balance at January 1	$	823	(a)	$	4	(b)	$	827	(a)	$	787		$	4		$	791
Liabilities incurred	—			—			—			21		(c)	—			21		(c)
Liabilities settled	(10)			—			(10)			(13)			—			(13)
Accretion(d)	36		(d)	—			36		(d)	35			—			35
Change in estimates	—			1			1			(7)			—			(7)
Ending balance at December 31	$	849	(a)(e)	$	5	(b)	$	854	(a)(e)	$	823	(a)(e)	$	4	(b)	$	827	(a)(e)

(a)Balance included $5 million and $5 million in “Other current liabilities” on the balance sheet as of December 31, 2025 and 2024, respectively.

(b)Included in “Other deferred credits and liabilities” on the balance sheet.

(c)In 2024, Ameren and Ameren Missouri recorded an ARO related to decommissioning for the Cass County, Boomtown, and Huck Finn energy centers. In addition, as a result of the 2024 CCR Rule, Ameren and Ameren Missouri recorded an increase to their AROs associated with CCR storage facilities. See Note 14 – Commitments and Contingencies for additional information.

(d)Accretion expense attributable to Ameren Missouri was recorded as a decrease to regulatory liabilities.

(e)The balance included an ARO related to the decommissioning of the Callaway Enter Center of $678 million and $648 million as of December 31, 2025 and 2024, respectively.

Deferred Compensation

As of December 31, 2025, and 2024, the present value of benefits to be paid for deferred compensation obligations was $79 million and $79 million, respectively, which was primarily reflected in “Other deferred credits and liabilities” on Ameren’s consolidated balance sheet. Deferred compensation obligations are primarily recorded on the balance sheet of Ameren (parent).

Excise Taxes

Ameren Missouri and Ameren Illinois collect from their customers excise taxes, including municipal and state excise taxes and gross receipts taxes, that are levied on the sale or distribution of natural gas and electricity. The following table presents the excise taxes recorded on a gross basis in “Operating Revenues – Electric,” “Operating Revenues – Natural gas” and “Operating Expenses – Taxes other than income taxes” on the statements of income for the years ended December 31, 2025, 2024, and 2023:


	2025		2024		2023
Ameren Missouri	$	189	$	169	$	166
Ameren Illinois	140		130		121
Ameren	$	329	$	299	$	287

Allowance for Funds Used During Construction

The following table presents the average rate that was applied to eligible construction work in progress and the amounts of allowance for funds used during construction capitalized in 2025, 2024, and 2023:


	2025			2024			2023
Average rate:
Ameren Missouri	7		%	6		%	6		%
Ameren Illinois	7		%	6		%	6		%
Ameren:
Allowance for equity funds used during construction	$	88		$	76		$	54
Allowance for borrowed funds used during construction	52			56			48
Total Ameren	$	140		$	132		$	102
Ameren Missouri:
Allowance for equity funds used during construction	$	56		$	58		$	30
Allowance for borrowed funds used during construction	36			39			27
Total Ameren Missouri	$	92		$	97		$	57
Ameren Illinois:
Allowance for equity funds used during construction	$	30		$	17		$	19
Allowance for borrowed funds used during construction	15			15			17
Total Ameren Illinois	$	45		$	32		$	36

Earnings per Share

Earnings per basic and diluted share are computed by dividing “Net Income Attributable to Ameren Common Shareholders” by the weighted-average number of basic and diluted common shares outstanding, respectively, during the applicable period. The weighted-average shares outstanding for earnings per diluted share includes the incremental effects resulting from performance share units, restricted stock units, and forward sale agreements relating to common stock when the impact would be dilutive, as calculated using the treasury stock method. For information regarding performance share units and restricted stock units, see Note 11 – Stock-based Compensation. For information regarding forward sale agreements, see Note 5 – Long-term Debt and Equity Financings.

The following table reconciles the weighted-average number of common shares outstanding to the diluted weighted-average number of common shares outstanding for the years ended December 31, 2025, 2024, and 2023:


	2025	2024	2023


Weighted-average Common Shares Outstanding – Basic	270.5	266.8	262.8
Assumed settlement of performance share units and restricted stock units	0.9	0.5	0.6
Dilutive effect of forward sale agreements	0.8	0.1	—
Weighted-average Common Shares Outstanding – Diluted(a)	272.2	267.4	263.4

(a)There was an immaterial number of anti-dilutive securities excluded from the earnings per diluted share calculations as calculated using the treasury stock method for the years ended December 31, 2025, 2024, and 2023 related to performance share units and restricted stock units. Outstanding forward sale agreements as of December 31, 2025 and 2024 that were anti-dilutive for the years ended December 31, 2025 and 2024, respectively, were excluded from the earnings per diluted share calculation as calculated using the treasury stock method. The outstanding forward sale agreements as of December 31, 2023, were anti-dilutive for the year ended December 31, 2023, and excluded from the earnings per diluted share calculation as calculated using the treasury stock method. For additional information about the outstanding forward sale agreements, see Note 5 – Long-term Debt and Equity Financings.

Supplemental Cash Flow Information

The following table provides noncash financing and investing activity excluded from the statements of cash flows for the years ended December 31, 2025, 2024, and 2023:


	December 31, 2025						December 31, 2024							December 31, 2023
	Ameren		Ameren Missouri		Ameren Illinois			Ameren		Ameren Missouri		Ameren Illinois			Ameren		Ameren Missouri		Ameren Illinois
Investing
Accrued capital expenditures, including nuclear fuel expenditures	$	622	$	355	$	210		$	480	$	303	$	157		$	518	$	270	$	212


Net realized and unrealized gain (loss) – nuclear decommissioning trust fund	160		160		—			165		165		—			167		167		—
Return of investment in industrial development revenue bonds(a)	—		—		—			—		—		—			240		240		—
Financing
Issuance of common stock for stock-based compensation	$	25	$	—	$	—		$	16	$	—	$	—		$	40	$	—	$	—
Issuance of common stock under the DRPlus	7		—		—			7		—		—			7		—		—
Termination of a financing agreement(a)	—		—		—			—		—		—			240		240		—

(a)In January 2023, Ameren Missouri and Audrain County mutually agreed to terminate a financing obligation agreement related to the CT energy center in Audrain County, which was scheduled to expire in December 2023. No cash was exchanged in connection with the termination of the agreement as the $240 million principal amount of the financing obligation due from Ameren Missouri was equal to the amount of bond service payments due to Ameren Missouri.

Segment Information

12 Months Ended

Dec. 31, 2025

Segment Reporting [Abstract]

SEGMENT INFORMATION

Ameren has four segments: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. The Ameren Missouri segment includes all of the operations of Ameren Missouri. Ameren Illinois Electric Distribution consists of the electric distribution business of Ameren Illinois. Ameren Illinois Natural Gas consists of the natural gas business of Ameren Illinois. Ameren Transmission primarily consists of the aggregated electric transmission businesses of Ameren Illinois and ATXI. The category called Other primarily includes Ameren (parent) activities and Ameren Services.

Ameren Missouri has one segment. Ameren Illinois has three segments: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. See Note 1 – Summary of Significant Accounting Policies for additional information regarding the operations of Ameren Missouri, Ameren Illinois, and ATXI.

Segment operating revenues and a majority of operating expenses are directly recognized and incurred by Ameren Illinois in each Ameren Illinois segment. Common operating expenses, miscellaneous income and expenses, interest charges, and income tax expense are allocated by Ameren Illinois to each Ameren Illinois segment based on certain factors, which primarily relate to the nature of the cost. Additionally, Ameren Illinois Transmission earns revenue from transmission service provided to Ameren Illinois Electric Distribution, other retail electric suppliers, and wholesale customers. The transmission expense for Illinois customers who have elected to purchase their power from Ameren Illinois is recovered through a cost recovery mechanism with no net effect on Ameren Illinois Electric Distribution earnings, as costs are offset by corresponding revenues. Transmission revenues from these transactions are reflected in Ameren Transmission’s and Ameren Illinois Transmission’s operating revenues. An intersegment elimination at Ameren and Ameren Illinois occurs to eliminate these transmission revenues and expenses.

The CODMs for Ameren, Ameren Missouri, and Ameren Illinois are the Chief Executive Officer of Ameren, the Group President of Ameren Utilities of Ameren, and the Chief Financial Officer of Ameren. The CODMs use net income to evaluate income generated from the segments to make decisions about resources allocated to each segment and assess segment performance. Net income is also used to monitor budget versus actual results when assessing segment performance.

The following tables present information about the reported revenue and specified items reflected in net income attributable to common shareholders and capital expenditures by segment at Ameren and Ameren Illinois for the years ended December 31, 2025, 2024, and 2023. Ameren, Ameren Missouri, and Ameren Illinois management review segment capital expenditure information rather than any individual or total asset amount.

Ameren


	Reportable Segments
	Ameren Missouri		Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission			Other		Intersegment Eliminations		Ameren
2025
External revenues	$	4,763	$	2,393	$	968	$	675		$	—	$	—	$	8,799
Intersegment revenues	32		6		—		187			—		(225)		—
Revenue	4,795		2,399		968		862			—		(225)		8,799
Fuel and purchased power(a)	(1,538)		(941)		—		—			—		173		(2,306)
Natural gas purchased for resale(a)	(65)		—		(283)		—			—		—		(348)
Other operations and maintenance expenses(a)	(1,029)		(656)		(233)		(74)			(34)		52		(1,974)
Other segment items
Depreciation and amortization	(860)		(373)		(128)		(199)			(8)		—		(1,568)
Taxes other than income taxes	(393)		(82)		(82)		(9)			(11)		—		(577)
Other income, net	180		89		19		24			42		(7)		347
Interest charges	(297)		(107)		(65)		(120)		(b)	(194)		7		(776)
Income taxes (benefit)	(43)		(47)		(38)		(68)			60		—		(136)
Noncontrolling interests – preferred stock dividends	(3)		(1)		—		(1)			—		—		(5)
Net income (loss) attributable to Ameren common shareholders	$	747	$	281	$	158	$	415		$	(145)	$	—	$	1,456

Interest income	$	9	$	30	$	—	$	3		$	6	$	(7)	$	41
Capital expenditures	2,502		635		283		717			8		(17)		4,128
2024
External revenues	$	3,960	$	2,088	$	938	$	637		$	—	$	—	$	7,623
Intersegment revenues	33		1		—		144			—		(178)		—
Revenue	3,993		2,089		938		781			—		(178)		7,623
Fuel and purchased power(a)	(1,071)		(740)		—		—			—		130		(1,681)
Natural gas purchased for resale(a)	(60)		—		(260)		—			—		—		(320)
Other operations and maintenance expenses(a)	(1,050)		(619)		(230)		(70)			(48)		48		(1,969)
Other segment items
Depreciation and amortization	(917)		(369)		(129)		(167)			(8)		—		(1,590)
Taxes other than income taxes	(372)		(75)		(78)		(9)			(13)		—		(547)
Other income, net	196		97		27		26			83		(12)		417
Interest charges	(244)		(98)		(63)		(117)		(b)	(153)		12		(663)
Income taxes (benefit)	87		(50)		(56)		(120)			56		—		(83)
Noncontrolling interests – preferred stock dividends	(3)		(1)		—		(1)			—		—		(5)
Net income (loss) attributable to Ameren common shareholders	$	559	$	234	$	149	$	323		$	(83)	$	—	$	1,182

Interest income	$	8	$	28	$	1	$	6		$	10	$	(12)	$	41
Capital expenditures	2,712		579		264		758			7		(1)		4,319


	Reportable Segments
	Ameren Missouri		Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission			Other		Intersegment Eliminations		Ameren
2023
External revenues	$	3,825	$	2,217	$	897	$	561		$	—	$	—	$	7,500
Intersegment revenues	34		1		—		116			—		(151)		—
Revenue	3,859		2,218		897		677			—		(151)		7,500
Fuel and purchased power(a)	(997)		(933)		—		—			—		118		(1,812)
Natural gas purchased for resale(a)	(79)		—		(276)		—			—		—		(355)
Other operations and maintenance expenses(a)	(1,003)		(532)		(237)		(60)			(67)		33		(1,866)
Other segment items
Depreciation and amortization	(783)		(351)		(108)		(138)			(7)		—		(1,387)
Taxes other than income taxes	(360)		(75)		(67)		(8)			(12)		—		(522)
Other income, net	130		103		30		28			62		(5)		348
Interest charges	(227)		(89)		(55)		(96)		(b)	(104)		5		(566)
Income taxes (benefit)	8		(82)		(50)		(106)			47		—		(183)
Noncontrolling interests – preferred stock dividends	(3)		(1)		—		(1)			—		—		(5)
Net income (loss) attributable to Ameren common shareholders	$	545	$	258	$	134	$	296		$	(81)	$	—	$	1,152

Interest income	$	11	$	19	$	1	$	2		$	5	$	(5)	$	33
Capital expenditures	1,760		752		299		804			9		(27)		3,597

(a)Significant segment expense that is regularly provided to the CODMs. Intersegment expenses are included within the amounts shown.

(b)Ameren Transmission interest charges include an allocation of financing costs from Ameren (parent).

Ameren Illinois


	Reportable Segments
	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Intersegment Eliminations		Ameren Illinois
2025
External revenues	$	2,399	$	968	$	477	$	—	$	3,844
Intersegment revenues	—		—		160		(160)		—
Revenue	2,399		968		637		(160)		3,844
Purchased power(a)	(941)		—		—		160		(781)
Natural gas purchased for resale(a)	—		(283)		—		—		(283)
Other operations and maintenance expenses(a)	(656)		(233)		(56)		—		(945)
Other segment items
Depreciation and amortization	(373)		(128)		(151)		—		(652)
Taxes other than income taxes	(82)		(82)		(5)		—		(169)
Other income, net	89		19		28		—		136
Interest charges	(107)		(65)		(88)		—		(260)
Income taxes	(47)		(38)		(68)		—		(153)
Noncontrolling interests – preferred stock dividends	(1)		—		(1)		—		(2)
Net income available to common shareholder	$	281	$	158	$	296	$	—	$	735

Interest income	$	30	$	—	$	2	$	—	$	32
Capital expenditures	635		283		563		—		1,481
2024
External revenues	$	2,089	$	938	$	445	$	—	$	3,472
Intersegment revenues	—		—		119		(119)		—
Revenue	2,089		938		564		(119)		3,472
Purchased power(a)	(740)		—		—		119		(621)
Natural gas purchased for resale(a)	—		(260)		—		—		(260)
Other operations and maintenance expenses(a)	(619)		(230)		(57)		—		(906)
Other segment items
Depreciation and amortization	(369)		(129)		(121)		—		(619)
Taxes other than income taxes	(75)		(78)		(4)		—		(157)
Other income, net	97		27		23		—		147
Interest charges	(98)		(63)		(80)		—		(241)
Income taxes	(50)		(56)		(87)		—		(193)
Noncontrolling interests – preferred stock dividends	(1)		—		(1)		—		(2)
Net income available to common shareholder	$	234	$	149	$	237	$	—	$	620

Interest income	$	28	$	1	$	3	$	—	$	32
Capital expenditures	579		264		624		—		1,467


	Reportable Segments
	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Intersegment Eliminations		Ameren Illinois
2023
External revenues	$	2,218	$	897	$	367	$	—	$	3,482
Intersegment revenues	—		—		113		(113)		—
Revenue	2,218		897		480		(113)		3,482
Purchased power(a)	(933)		—		—		113		(820)
Natural gas purchased for resale(a)	—		(276)		—		—		(276)
Other operations and maintenance expenses(a)	(532)		(237)		(49)		—		(818)
Other segment items
Depreciation and amortization	(351)		(108)		(97)		—		(556)
Taxes other than income taxes	(75)		(67)		(4)		—		(146)
Other income, net	103		30		23		—		156
Interest charges	(89)		(55)		(60)		—		(204)
Income taxes	(82)		(50)		(77)		—		(209)
Noncontrolling interests – preferred stock dividends	(1)		—		(1)		—		(2)
Net income available to common shareholder	$	258	$	134	$	215	$	—	$	607

Interest income	$	19	$	1	$	1	$	—	$	21
Capital expenditures	752		299		680		—		1,731

(a)Significant segment expense that is regularly provided to the CODMs. Intersegment expenses are included within the amounts shown.

The following tables present disaggregated revenues by segment at Ameren and Ameren Illinois for the years ended December 31, 2025, 2024, and 2023. Economic factors affect the nature, timing, amount, and uncertainty of revenues and cash flows in a similar manner across customer classes. Revenues from alternative revenue programs have a similar distribution among customer classes as revenues from contracts with customers. Other revenues not associated with contracts with customers are presented in the Other customer classification, along with electric transmission and off-system sales and capacity revenues.

Ameren


	Ameren Missouri		Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission		Intersegment Eliminations		Ameren
2025
Residential	$	1,839	$	1,483	$	—	$	—	$	—	$	3,322
Commercial	1,450		785		—		—		—		2,235
Industrial	342		199		—		—		—		541
Other	1,000		(68)		—		862		(224)		1,570
Total electric revenues	$	4,631	$	2,399	$	—	$	862	$	(224)	$	7,668
Residential	$	101	$	—	$	680	$	—	$	—	$	781
Commercial	44		—		185		—		—		229
Industrial	5		—		12		—		—		17
Other	14		—		91		—		(1)		104
Total gas revenues	$	164	$	—	$	968	$	—	$	(1)	$	1,131
Total revenues(a)	$	4,795	$	2,399	$	968	$	862	$	(225)	$	8,799
2024
Residential	$	1,638	$	1,254	$	—	$	—	$	—	$	2,892
Commercial	1,313		680		—		—		—		1,993
Industrial	311		178		—		—		—		489
Other	585		(23)		—		781		(177)		1,166
Total electric revenues	$	3,847	$	2,089	$	—	$	781	$	(177)	$	6,540
Residential	$	90	$	—	$	661	$	—	$	—	$	751
Commercial	37		—		166		—		—		203
Industrial	4		—		10		—		—		14
Other	15		—		101		—		(1)		115
Total gas revenues	$	146	$	—	$	938	$	—	$	(1)	$	1,083
Total revenues(a)	$	3,993	$	2,089	$	938	$	781	$	(178)	$	7,623
2023
Residential	$	1,577	$	1,344	$	—	$	—	$	—	$	2,921
Commercial	1,280		747		—		—		—		2,027
Industrial	306		186		—		—		—		492
Other	531		(59)		—		677		(150)		999
Total electric revenues	$	3,694	$	2,218	$	—	$	677	$	(150)	$	6,439
Residential	$	100	$	—	$	657	$	—	$	—	$	757
Commercial	46		—		164		—		—		210
Industrial	5		—		14		—		—		19
Other	14		—		62		—		(1)		75
Total gas revenues	$	165	$	—	$	897	$	—	$	(1)	$	1,061
Total revenues(a)	$	3,859	$	2,218	$	897	$	677	$	(151)	$	7,500

(a)The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the years ended December 31, 2025, 2024, and 2023:


	Ameren Missouri			Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Transmission		Intersegment Eliminations		Ameren
2025
Revenues from alternative revenue programs	$	(5)		$	(135)	$	(34)	$	(26)	$	—	$	(200)
Other revenues not from contracts with customers	6		(a)	13		3		—		(4)		18		(a)
2024
Revenues from alternative revenue programs	$	4		$	(43)	$	(3)	$	33	$	—	$	(9)
Other revenues not from contracts with customers	7		(a)	10		2		—		—		19		(a)
2023
Revenues from alternative revenue programs	$	(5)		$	116	$	49	$	19	$	—	$	179
Other revenues not from contracts with customers	(9)		(a)	7		2		—		—		—		(a)

(a)Includes net realized gains and losses on derivative power contracts.

Ameren Illinois


	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Intersegment Eliminations		Ameren Illinois
2025
Residential	$	1,483	$	680	$	—	$	—	$	2,163
Commercial	785		185		—		—		970
Industrial	199		12		—		—		211
Other	(68)		91		637		(160)		500
Total revenues(a)	$	2,399	$	968	$	637	$	(160)	$	3,844
2024
Residential	$	1,254	$	661	$	—	$	—	$	1,915
Commercial	680		166		—		—		846
Industrial	178		10		—		—		188
Other	(23)		101		564		(119)		523
Total revenues(a)	$	2,089	$	938	$	564	$	(119)	$	3,472
2023
Residential	$	1,344	$	657	$	—	$	—	$	2,001
Commercial	747		164		—		—		911
Industrial	186		14		—		—		200
Other	(59)		62		480		(113)		370
Total revenues(a)	$	2,218	$	897	$	480	$	(113)	$	3,482

(a)The following table presents increases/(decreases) in revenues from alternative revenue programs and other revenues not from contracts with customers for the Ameren Illinois segments for the years ended December 31, 2025, 2024, and 2023:


	Ameren Illinois Electric Distribution		Ameren Illinois Natural Gas		Ameren Illinois Transmission		Ameren Illinois
2025
Revenues from alternative revenue programs	$	(135)	$	(34)	$	(19)	$	(188)
Other revenues not from contracts with customers	13		3		—		16
2024
Revenues from alternative revenue programs	$	(43)	$	(3)	$	29	$	(17)
Other revenues not from contracts with customers	10		2		—		12
2023
Revenues from alternative revenue programs	$	116	$	49	$	12	$	177
Other revenues not from contracts with customers	7		2		—		9

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/exampleRef
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+ Details

Schedule I - Condensed Financial Information Of Parent

12 Months Ended

Dec. 31, 2025

Condensed Financial Information Disclosure [Abstract]

Condensed Financial Information Of Parent


SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED STATEMENT OF INCOME AND COMPREHENSIVE INCOME For the Years Ended December 31, 2025, 2024, and 2023
(In millions)	2025		2024		2023
Operating revenues	$	—	$	—	$	—
Operating expenses	19		17		22
Operating loss	(19)		(17)		(22)
Equity in earnings of subsidiaries	1,596		1,271		1,245
Interest income from affiliates	11		14		10
Total other income (expense), net	—		3		(11)
Interest charges	(196)		(162)		(119)
Income tax benefit	59		61		49


Net Income Attributable to Ameren Common Shareholders	$	1,451	$	1,170	$	1,152

Net Income Attributable to Ameren Common Shareholders	$	1,451	$	1,170	$	1,152
Other Comprehensive Income (Loss), Net of Taxes:
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $1, $—, and $(2), respectively	3		(3)		(5)
Unrealized net gain on derivative hedging instruments, net of income taxes of $2, $—, and $—, respectively	3		3		—




Comprehensive Income Attributable to Ameren Common Shareholders	$	1,457	$	1,170	$	1,147


SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED BALANCE SHEET
(In millions, except per share amounts)	December 31, 2025		December 31, 2024
Assets:
Cash and cash equivalents	$	—	$	—
Advances to money pool	177		103
Accounts receivable – affiliates	11		41

Miscellaneous accounts receivable	32		35
Mark-to-market derivative assets	8		3


Total current assets	228		182

Investments in subsidiaries	17,360		16,262
Investments in subsidiary debt securities	69		44

Accumulated deferred income taxes, net	85		98
Other assets	114		155
Total assets	$	17,856	$	16,741
Liabilities and Shareholders’ Equity:
Current maturities of long-term debt	$	950	$	—
Short-term debt	155		1,055


Taxes accrued	6		7
Accounts payable – affiliates	24		49
Other current liabilities	66		54
Total current liabilities	1,201		1,165
Long-term debt, net	3,181		3,383
Pension and other postretirement benefits	19		18
Other deferred credits and liabilities	71		73
Total liabilities	4,472		4,639
Commitments and Contingencies (Note 4)
Shareholders’ Equity:
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 276.4 and 269.9, respectively	3		3
Other paid-in capital, principally premium on common stock	8,106		7,513
Retained earnings	5,275		4,592
Accumulated other comprehensive loss	—		(6)
Total shareholders’ equity	13,384		12,102
Total liabilities and shareholders’ equity	$	17,856	$	16,741


SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT AMEREN CORPORATION CONDENSED STATEMENT OF CASH FLOWS For the Years Ended December 31, 2025, 2024, and 2023
(In millions)	2025		2024		2023
Net cash provided by (used in) operating activities	$	451	$	(65)	$	171
Cash flows from investing activities:
Money pool advances, net	(74)		495		(530)

Investments in subsidiaries	(51)		(557)		(109)
Investments in subsidiary debt securities	(24)		(44)		—


Other	62		1		5
Net cash used in investing activities	(87)		(105)		(634)
Cash flows from financing activities:
Dividends on common stock	(768)		(714)		(662)
Short-term debt, net	(899)		1,054		(475)

Maturities of long-term debt	—		(450)		—
Issuances of long-term debt	749		—		1,298
Issuances of common stock	574		273		346

Employee payroll taxes related to stock-based compensation	(13)		(8)		(20)
Debt issuance costs	(7)		(1)		(8)

Net cash provided by (used in) financing activities	(364)		154		479
Net change in cash, cash equivalents, and restricted cash	$	—	$	(16)	$	16
Cash, cash equivalents, and restricted cash at beginning of year	—		16		—
Cash, cash equivalents, and restricted cash at end of year	$	—	$	—	$	16
Supplemental information:
Cash dividends received from consolidated subsidiaries	$	550	$	140	$	173


Noncash financing activity – Issuance of common stock for stock-based compensation	25		16		40
Noncash financing activity – Issuance of common stock under the DRPlus	7		7		7

AMEREN CORPORATION (parent company only)

NOTES TO CONDENSED FINANCIAL STATEMENTS December 31, 2025

NOTE 1 – BASIS OF PRESENTATION

Ameren Corporation (parent company only) is a public utility holding company that conducts substantially all of its business operations through its subsidiaries. Ameren Corporation (parent company only) has accounted for its subsidiaries using the equity method. These financial statements are presented on a condensed basis.

See Note 1 – Summary of Significant Accounting Policies and Note 15 – Supplemental Information under Part II, Item 8, of this report for additional information.

NOTE 2 – SHORT-TERM DEBT AND LIQUIDITY

Ameren, Ameren Services, and other non-state-regulated Ameren subsidiaries have the ability, subject to Ameren parent company and applicable regulatory short-term borrowing authorizations, to access funding from the Credit Agreements and the commercial paper programs through a non-state-regulated subsidiary money pool agreement. All participants may borrow from or lend to the non-state-regulated money pool. The total amount available to pool participants from the non-state-regulated subsidiary money pool at any given time is reduced by the amount of borrowings made by participants, but is increased to the extent that the pool participants advance surplus funds to the non-state-regulated subsidiary money pool or remit funds from other external sources. The non-state-regulated subsidiary money pool was established to coordinate and to provide short-term cash and working capital for the participants. Participants receiving a loan under the non-state-regulated subsidiary money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the non-state-regulated subsidiary money pool. Interest revenues related to non-state-regulated money pool advances were immaterial in 2025, 2024 and 2023, respectively. Interest charges related to non-state-regulated money pool borrowings were immaterial in 2025, 2024, and 2023.

See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for a description and details of short-term debt and liquidity needs of Ameren Corporation (parent company only).

NOTE 3 – LONG-TERM OBLIGATIONS

See Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report for additional information on Ameren Corporation’s (parent company only) long-term debt, indenture provisions, forward sale agreements related to common stock, and ATM program.

NOTE 4 – COMMITMENTS AND CONTINGENCIES

See Note 14 – Commitments and Contingencies under Part II, Item 8, of this report for a description of all material contingencies of Ameren Corporation (parent company only).

NOTE 5 – TOTAL OTHER INCOME (EXPENSE), NET

The following table presents the components of “Total Other Expense, Net” in the Condensed Statement of Income and Comprehensive Income for the years ended December 31, 2025, 2024, and 2023:


(In millions)	2025		2024		2023
Total other income (expense), net
Non-service cost components of net periodic benefit income	$	1	$	4	$	8
Donations	—		—		(18)
Other expense, net	(1)		(1)		(1)
Total other income (expense), net	$	—	$	3	$	(11)

Other Income And Expenses

OTHER INCOME, NET

The following table presents the components of “Other Income, Net” in the Ameren Companies’ statements of income for the years ended December 31, 2025, 2024, and 2023:


	2025		2024		2023
Ameren:
Other Income, Net
Allowance for equity funds used during construction	$	88	$	76	$	54
Other interest income	41		41		33
Non-service cost components of net periodic benefit income(a)	247		304		295
Miscellaneous income	17		9		7
Gain on extinguishment of debt(b)	8		16		—
Earnings (losses) related to equity method investments	(19)		(4)		1
Donations	(12)		(5)		(24)
Miscellaneous expense	(23)		(20)		(18)
Total Other Income, Net	$	347	$	417	$	348
Ameren Missouri:
Other Income, Net
Allowance for equity funds used during construction	$	56	$	58	$	30
Other interest income	9		8		11
Non-service cost components of net periodic benefit income(a)	126		139		97
Miscellaneous income	6		4		3
Donations	(7)		(2)		(2)
Miscellaneous expense	(10)		(11)		(9)
Total Other Income, Net	$	180	$	196	$	130
Ameren Illinois:
Other Income, Net
Allowance for equity funds used during construction	$	30	$	17	$	19
Other Interest income	32		32		21
Non-service cost components of net periodic benefit income	81		105		124
Miscellaneous income	9		4		4
Donations	(5)		(3)		(4)
Miscellaneous expense	(11)		(8)		(8)
Total Other Income, Net	$	136	$	147	$	156

(a)For the years ended December 31, 2025, 2024, and 2023, the non-service cost components of net periodic benefit income were adjusted by amounts deferred of $(53) million, $(41) million, and $27 million, respectively, due to a regulatory tracking mechanism for the difference between the level of such costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates. See Note 10 – Retirement Benefits for additional information.

(b)See Note 5 – Long-term Debt and Equity Financings for additional information on Ameren (parent)’s repurchase of Ameren Missouri’s senior secured notes and first mortgage bonds and Ameren Illinois’ first mortgage bonds that were accounted for as a debt extinguishment.

The following table presents the components of “Total Other Expense, Net” in the Condensed Statement of Income and Comprehensive Income for the years ended December 31, 2025, 2024, and 2023:


(In millions)	2025		2024		2023
Total other income (expense), net
Non-service cost components of net periodic benefit income	$	1	$	4	$	8
Donations	—		—		(18)
Other expense, net	(1)		(1)		(1)
Total other income (expense), net	$	—	$	3	$	(11)

Schedule II - Valuation And Qualifying Accounts

12 Months Ended

Dec. 31, 2025

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Valuation And Qualifying Accounts


SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS FOR THE YEARS ENDED DECEMBER 31, 2025, 2024, AND 2023
(In millions)
Column A	Column B		Column C				Column D		Column E
Description	Balance at Beginning of Period		(1) Charged to Costs and Expenses		(2) Charged to Other Accounts(a)		Deductions(b)		Balance at End of Period
Ameren:
Deducted from assets – allowance for doubtful accounts:
2025	$	30	$	51	$	7	$	49	$	39
2024	30		39		8		47		30
2023	31		51		5		57		30




Ameren Missouri:
Deducted from assets – allowance for doubtful accounts:
2025	$	12	$	17	$	—	$	12	$	17
2024	12		11		—		11		12
2023	13		11		—		12		12




Ameren Illinois:
Deducted from assets – allowance for doubtful accounts:
2025	$	18	$	34	$	7	$	37	$	22
2024	18		28		8		36		18
2023	18		40		5		45		18

(a)Amounts associated with the allowance for doubtful accounts relate to the uncollectible account reserve associated with receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act.

(b)Uncollectible accounts charged off, less recoveries.

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2025
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Insider Trading Policies and Procedures	12 Months Ended
Insider Trading Policies and Procedures	Dec. 31, 2025
Insider Trading Policies and Procedures [Line Items]
Insider Trading Policies and Procedures Adopted	true

Cybersecurity Risk Management and Strategy Disclosure	12 Months Ended
Cybersecurity Risk Management and Strategy Disclosure	Dec. 31, 2025
Cybersecurity Risk Management, Strategy, and Governance [Line Items]
Cybersecurity Risk Management Processes for Assessing, Identifying, and Managing Threats [Text Block]	The Ameren Companies have identified cybersecurity as an enterprise risk, which is managed through Ameren's integrated enterprise risk management program. The program is designed to continuously assess risk and evaluate the likelihood and probability of impact to determine the appropriate risk tolerance and risk management strategies that inform our cybersecurity policies, investments, practices, controls, and countermeasures. The program is a comprehensive, consistently applied management framework that is designed to ensure all forms of material risk and opportunity are identified, reported, and managed in an effective manner overseen by the risk management steering committee. The risk management steering committee, which is composed of executive management and senior-level Ameren officers, with Ameren board of directors’ oversight, oversees and governs Ameren's enterprise risk management processes, which include the identification, assessment, mitigation, and monitoring of risks including strategic, operational, and cybersecurity risks. Ameren's board of directors maintains a standing committee, the Cybersecurity and Digital Technology Committee, which is focused on the oversight of Ameren's cybersecurity and digital technology risks. The committee has primary responsibility for oversight of cybersecurity and digital technology risk management, including the programs, policies, procedures, processes, controls and safeguards for digital technology, information security, prevention and detection of cybersecurity incidents or data breaches, legislative and regulatory compliance, and cybersecurity and digital technology matters as they relate to crisis preparedness, incident response plans, and disaster recovery and business continuity capabilities. The committee receives regular updates from the Chief Information Security Officer, the Chief Digital and Information Officer, executive management, and other members of senior management who collectively maintain the responsibility for both the execution and ongoing management of Ameren’s cybersecurity program and respective initiatives. The Cybersecurity and Digital Technology Committee regularly reports on its activities to Ameren’s board of directors, including reviewing and advising Ameren’s board of directors of any developments it believes should be considered. Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who has nearly two decades of experience in cybersecurity, information technology, risk management, and business operations across the power and utilities sector and other industries. The Chief Information Security Officer provides strategic leadership and vision to strengthen Ameren’s security posture and promote resilience in an evolving threat landscape. The Chief Information Security Officer regularly engages with senior-level Ameren officers, reports to the risk management steering committee, and has recurring meetings with the Cybersecurity and Digital Technology Committee as part of ongoing risk management and oversight of the cybersecurity program. In addition, Ameren’s board of directors participates in threat briefings and periodic drills to prepare for potential crisis scenarios. To manage against existing and emerging cybersecurity threats, we maintain enterprise-wide cybersecurity, crisis management, and information security policies and regular awareness training and tests that reinforce the acceptable use of Ameren's information assets, protection of customer and employee data, and the role each employee plays in protecting Ameren against cybersecurity threats. Incident response plans and procedures are continuously tested through recurring companywide cybersecurity exercises to promote readiness across the organization. The plans and procedures are also designed to escalate incidents to appropriate members of management to guide the prevention, detection, response, recovery, and remediation from a material cybersecurity incident. These cybersecurity plans and procedures are positioned to promote the expedient identification, escalation, handling and reporting of a potentially material cybersecurity event or incident. To address cybersecurity threats, we work closely with law enforcement, cybersecurity consulting firms, and industry associations to enhance information sharing and guard against cybersecurity attacks. Ameren applies a third-party cybersecurity risk management program, which extends the governance elements of Ameren’s cybersecurity program, in addition to other diligence measures, to our critical third-party providers and suppliers. The supply chain and third-party risks introduced to Ameren are evaluated prior to the commencement of any new engagement or relationship, monitored closely throughout the lifecycle of the supplier relationship and managed through data privacy and cybersecurity provisions within the respective commercial contracts. Procedures have been established to address supplier incidents as well as supplier off-boarding at the expiration of the relationship. We leverage common and widely accepted external cybersecurity risk management frameworks, such as the National Institute of Standards and Technology Cybersecurity framework, to assess, guide, and enhance our cybersecurity posture. Our program effectiveness is measured through formal cybersecurity scorecards and metrics reported to senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee. These metrics include but are not limited to measures on the effectiveness of our cybersecurity controls across core National Institute of Standards and Technology Cybersecurity framework functions (Govern, Identify, Protect, Detect, Respond, and Recover), our ability to manage first- and third-party cybersecurity events and incidents, cybersecurity incident response exercises, results of our recurring internal assessments, vulnerability assessments, penetration tests, external assessments, and audits that Ameren regularly undergoes. Ameren regularly engages external cybersecurity experts to assist with evaluating our cybersecurity program. These engagements provide insights into control design and implementation, prioritized recommendations for enhancements to our cybersecurity strategy, and an overview of the cybersecurity threat landscape that collectively inform our investments and technical controls to protect Ameren's most critical assets. The results of these engagements are reviewed with senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee. We are not aware of any cybersecurity events that have materially affected or are reasonably likely to materially affect Ameren, including our business strategy, results of operations, financial position, or liquidity.
Cybersecurity Risk Management Processes Integrated [Flag]	true
Cybersecurity Risk Management Processes Integrated [Text Block]	The Ameren Companies have identified cybersecurity as an enterprise risk, which is managed through Ameren's integrated enterprise risk management program. The program is designed to continuously assess risk and evaluate the likelihood and probability of impact to determine the appropriate risk tolerance and risk management strategies that inform our cybersecurity policies, investments, practices, controls, and countermeasures. The program is a comprehensive, consistently applied management framework that is designed to ensure all forms of material risk and opportunity are identified, reported, and managed in an effective manner overseen by the risk management steering committee.
Cybersecurity Risk Management Third Party Engaged [Flag]	true
Cybersecurity Risk Third Party Oversight and Identification Processes [Flag]	true
Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag]	false
Cybersecurity Risk Board of Directors Oversight [Text Block]	Ameren's board of directors maintains a standing committee, the Cybersecurity and Digital Technology Committee, which is focused on the oversight of Ameren's cybersecurity and digital technology risks. The committee has primary responsibility for oversight of cybersecurity and digital technology risk management, including the programs, policies, procedures, processes, controls and safeguards for digital technology, information security, prevention and detection of cybersecurity incidents or data breaches, legislative and regulatory compliance, and cybersecurity and digital technology matters as they relate to crisis preparedness, incident response plans, and disaster recovery and business continuity capabilities. The committee receives regular updates from the Chief Information Security Officer, the Chief Digital and Information Officer, executive management, and other members of senior management who collectively maintain the responsibility for both the execution and ongoing management of Ameren’s cybersecurity program and respective initiatives. The Cybersecurity and Digital Technology Committee regularly reports on its activities to Ameren’s board of directors, including reviewing and advising Ameren’s board of directors of any developments it believes should be considered. Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who has nearly two decades of experience in cybersecurity, information technology, risk management, and business operations across the power and utilities sector and other industries. The Chief Information Security Officer provides strategic leadership and vision to strengthen Ameren’s security posture and promote resilience in an evolving threat landscape. The Chief Information Security Officer regularly engages with senior-level Ameren officers, reports to the risk management steering committee, and has recurring meetings with the Cybersecurity and Digital Technology Committee as part of ongoing risk management and oversight of the cybersecurity program. In addition, Ameren’s board of directors participates in threat briefings and periodic drills to prepare for potential crisis scenarios. To manage against existing and emerging cybersecurity threats, we maintain enterprise-wide cybersecurity, crisis management, and information security policies and regular awareness training and tests that reinforce the acceptable use of Ameren's information assets, protection of customer and employee data, and the role each employee plays in protecting Ameren against cybersecurity threats. Incident response plans and procedures are continuously tested through recurring companywide cybersecurity exercises to promote readiness across the organization. The plans and procedures are also designed to escalate incidents to appropriate members of management to guide the prevention, detection, response, recovery, and remediation from a material cybersecurity incident. These cybersecurity plans and procedures are positioned to promote the expedient identification, escalation, handling and reporting of a potentially material cybersecurity event or incident. To address cybersecurity threats, we work closely with law enforcement, cybersecurity consulting firms, and industry associations to enhance information sharing and guard against cybersecurity attacks. Ameren applies a third-party cybersecurity risk management program, which extends the governance elements of Ameren’s cybersecurity program, in addition to other diligence measures, to our critical third-party providers and suppliers. The supply chain and third-party risks introduced to Ameren are evaluated prior to the commencement of any new engagement or relationship, monitored closely throughout the lifecycle of the supplier relationship and managed through data privacy and cybersecurity provisions within the respective commercial contracts. Procedures have been established to address supplier incidents as well as supplier off-boarding at the expiration of the relationship. We leverage common and widely accepted external cybersecurity risk management frameworks, such as the National Institute of Standards and Technology Cybersecurity framework, to assess, guide, and enhance our cybersecurity posture. Our program effectiveness is measured through formal cybersecurity scorecards and metrics reported to senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee. These metrics include but are not limited to measures on the effectiveness of our cybersecurity controls across core National Institute of Standards and Technology Cybersecurity framework functions (Govern, Identify, Protect, Detect, Respond, and Recover), our ability to manage first- and third-party cybersecurity events and incidents, cybersecurity incident response exercises, results of our recurring internal assessments, vulnerability assessments, penetration tests, external assessments, and audits that Ameren regularly undergoes. Ameren regularly engages external cybersecurity experts to assist with evaluating our cybersecurity program. These engagements provide insights into control design and implementation, prioritized recommendations for enhancements to our cybersecurity strategy, and an overview of the cybersecurity threat landscape that collectively inform our investments and technical controls to protect Ameren's most critical assets. The results of these engagements are reviewed with senior-level Ameren officers, the risk management steering committee, and the Cybersecurity and Digital Technology Committee.
Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block]	Ameren's board of directors maintains a standing committee, the Cybersecurity and Digital Technology Committee, which is focused on the oversight of Ameren's cybersecurity and digital technology risks.
Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block]	The committee has primary responsibility for oversight of cybersecurity and digital technology risk management, including the programs, policies, procedures, processes, controls and safeguards for digital technology, information security, prevention and detection of cybersecurity incidents or data breaches, legislative and regulatory compliance, and cybersecurity and digital technology matters as they relate to crisis preparedness, incident response plans, and disaster recovery and business continuity capabilities.
Cybersecurity Risk Role of Management [Text Block]	Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who has nearly two decades of experience in cybersecurity, information technology, risk management, and business operations across the power and utilities sector and other industries. The Chief Information Security Officer provides strategic leadership and vision to strengthen Ameren’s security posture and promote resilience in an evolving threat landscape. The Chief Information Security Officer regularly engages with senior-level Ameren officers, reports to the risk management steering committee, and has recurring meetings with the Cybersecurity and Digital Technology Committee as part of ongoing risk management and oversight of the cybersecurity program. In addition, Ameren’s board of directors participates in threat briefings and periodic drills to prepare for potential crisis scenarios.
Cybersecurity Risk Management Positions or Committees Responsible [Flag]	true
Cybersecurity Risk Management Positions or Committees Responsible [Text Block]	Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who has nearly two decades of experience in cybersecurity, information technology, risk management, and business operations across the power and utilities sector and other industries.
Cybersecurity Risk Management Expertise of Management Responsible [Text Block]	Ameren's cybersecurity program and team are led by the Chief Information Security Officer, who has nearly two decades of experience in cybersecurity, information technology, risk management, and business operations across the power and utilities sector and other industries.
Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block]	The plans and procedures are also designed to escalate incidents to appropriate members of management to guide the prevention, detection, response, recovery, and remediation from a material cybersecurity incident. These cybersecurity plans and procedures are positioned to promote the expedient identification, escalation, handling and reporting of a potentially material cybersecurity event or incident.
Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag]	true

Summary Of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Nature of Operations

General

Ameren, headquartered in St. Louis, Missouri, is a public utility holding company whose primary assets are its equity interests in its subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below. Ameren also has other subsidiaries that conduct other activities, such as providing shared services.

•Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas distribution business in Missouri. Ameren Missouri was incorporated in Missouri in 1922 and is successor to a number of companies, the oldest of which was organized in 1881. It is the largest electric utility in the state of Missouri. It supplies electric and natural gas service to a 24,000-square-mile area in central and eastern Missouri, which includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.3 million customers and natural gas service to 0.1 million customers.

•Ameren Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric transmission, electric distribution, and natural gas distribution businesses in Illinois. Ameren Illinois was incorporated in Illinois in 1923 and is the successor to a number of companies, the oldest of which was organized in 1902. Ameren Illinois supplies electric and natural gas utility service to a 43,700 square mile area in central and southern Illinois. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 0.8 million customers.

•ATXI operates a FERC rate-regulated electric transmission business in the MISO. ATXI was incorporated in Illinois in 2006.

Consolidation

Ameren’s and Ameren Missouri’s financial statements are prepared on a consolidated basis and therefore include the accounts of their majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren Illinois has no subsidiaries. All tabular dollar amounts are in millions, unless otherwise indicated.

Note 1 – Summary of Significant Accounting Policies applies to the Ameren Companies. The remaining notes to the consolidated financial statements apply to the registrants as indicated in each footnote disclosure. Registrants are named specifically for their related activities and disclosures.

Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair presentation of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.

Public Utilities

Regulation

Our customer rates are regulated by the MoPSC, the ICC, and the FERC. We defer certain costs as assets pursuant to actions of rate regulators or because of expectations that we will be able to recover such costs in future rates charged to customers. We also defer certain amounts as liabilities pursuant to actions of rate regulators or based on the expectation that such amounts will be refunded to customers in future rates. Regulatory assets and liabilities are amortized consistent with the period of expected regulatory treatment. See Note 2 – Rate and Regulatory Matters for additional information on our regulatory frameworks, regulatory recovery mechanisms, and regulatory assets and liabilities recorded at December 31, 2025 and 2024.

We periodically assess the recoverability of our regulatory assets and probability of refund of our regulatory liabilities. Regulatory assets are charged to earnings when it is no longer probable that such amounts will be recovered through future revenues. To the extent that refunds to customers related to regulatory liabilities are eliminated by the regulator or are no longer probable, the amounts are credited to earnings.

Environmental Costs

Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are expensed or deferred as a regulatory asset when it is probable that the costs will be recovered from customers in future rates. See Note 14 – Commitments and Contingencies for additional information on liabilities for environmental costs.

Cash and Cash Equivalents

Cash, Cash Equivalents, and Restricted Cash

Cash and cash equivalents include short-term, highly liquid investments purchased with an original maturity of three months or less. Cash and cash equivalents subject to legal or contractual restrictions and not readily available for use for general corporate purposes are

classified as restricted cash. See Note 15 – Supplemental Information for a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets and the statements of cash flows.

Allowance for Doubtful Accounts Receivable

The allowance for doubtful accounts represents our estimate of existing accounts receivable that will ultimately be uncollectible. The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue. We estimate future collections success using loss factors such as account aging, customer-specific considerations, and forecasted economic conditions. Accounts receivables are written off when all reasonable collection efforts have been completed. Ameren Illinois has bad debt riders that adjust rates for net write-offs of customer accounts receivable above or below those being collected in rates.

Inventories

Inventories are recorded at the lower of weighted-average cost or net realizable value. Inventories are charged to expense or capitalized to property, plant and equipment when issued, as appropriate, using the weighted-average cost method. See Note 15 – Supplemental Information for the components of inventories.

Property and Plant

Property, Plant, and Equipment, Net

We capitalize the cost of additions to, and betterments of, units of property, plant, and equipment. The cost includes labor, material, overheads, and applicable taxes. An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets. Maintenance expenditures are expensed as incurred unless subject to regulatory deferral. When units of depreciable tangible property are retired, the original costs, and the associated removal cost, net of salvage, are charged to accumulated depreciation. If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset. See Asset Retirement Obligations and Removal Costs section below and Note 3 – Property, Plant, and Equipment, Net for additional information.

Ameren Missouri’s cost of nuclear fuel is capitalized as a part of “Property, Plant, and Equipment, Net” on Ameren and Ameren Missouri’s balance sheets and then amortized to “Operating Expenses – Fuel and purchased power” in their respective statements of income on a unit-of-production basis. Nuclear fuel amortization is reflected as a part of “Amortization of nuclear fuel” on their respective statements of cash flows.

When it becomes probable an asset will be retired significantly in advance of its previously expected useful life and in the near term, the Ameren Companies must assess the probability of recovery of the remaining net book value of the asset to be abandoned. We recognize a loss on abandonment when it becomes probable that all or part of the cost of an asset, including a return at the applicable WACC, will be disallowed from recovery either through customer rates or through the issuance of securitized utility tariff bonds and such amount is reasonably estimable.

In addition, the Ameren Companies must assess the likelihood of a disallowance that part of the cost of a plant under construction or a recently completed plant will be disallowed for ratemaking purposes. Factors can include our own recent rate orders, as well as recent rate orders of other regulated entities in similar jurisdictions. If a disallowance becomes probable and reasonably estimable, we record an impairment charge in the period in which we determine the plant has met the criteria.

We also evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. Whether an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value of the assets. In the period in which we determine that an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its estimated fair value less cost to sell. We did not identify any material events or changes in circumstances that indicated that the carrying value of long-lived assets may not be recoverable in 2025, 2024, or 2023.

Depreciation

Depreciation is recognized over the estimated lives of the many classes of depreciable tangible property by applying composite rates on a straight-line basis to the original cost of such property. The composite rates include a provision for the estimated removal cost of property, plant, and equipment retired from service, net of salvage. See Asset Retirement Obligation and Removal Costs section below for additional information. The provision for depreciation for the Ameren Companies in 2025, 2024, and 2023 ranged from 3% to 4% of the average depreciable cost. See Note 3 – Property, Plant, and Equipment, Net for additional information on estimated depreciable lives.

Allowance for Funds Used During Construction

As a part of “Property, Plant, and Equipment, Net” on the balance sheet, we capitalize allowance for funds used during construction, which is the cost of borrowed funds and the cost of equity funds (preferred and common shareholders’ equity) applicable to eligible rate-regulated construction work in progress, in accordance with the utility industry’s accounting practice and GAAP. The amount of allowance for funds used during construction is calculated using a FERC-prescribed formula based on a rate, which incorporates the average cost of short-term debt, the average cost of long-term debt, and the cost of equity funds. The portion attributable to borrowed funds is recorded as a reduction of “Interest Charges” on the statements of income. The portion attributable to equity funds is recorded within “Other Income, Net” on the statements of income. This accounting practice offsets the effect on earnings of the cost of financing during construction. See Note 15 – Supplemental Information for the amount of allowance for funds used during construction capitalized and the average rate applied to eligible construction work in progress.

Allowance for funds used during construction does not represent a current source of cash funds. Under accepted ratemaking practice, cash recovery of allowance for funds used during construction and other construction costs occurs when completed projects are placed in service and reflected in customer rates.

Goodwill

Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired. Ameren and Ameren Illinois had goodwill of $411 million at December 31, 2025 and 2024. Ameren has four reporting units: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. Ameren Illinois has three reporting units: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission had goodwill of $238 million, $80 million, and $93 million, respectively, at December 31, 2025 and 2024. The Ameren Transmission reporting unit had the same $93 million of goodwill as the Ameren Illinois Transmission reporting unit at December 31, 2025 and 2024.

Ameren and Ameren Illinois evaluate goodwill for impairment in each of their reporting units as of October 31 each year, or more frequently if events occur or circumstances change that would more likely than not reduce the fair value of their reporting units below their carrying amounts. To determine whether the fair value of a reporting unit is more likely than not greater than its carrying amount, Ameren and Ameren Illinois can elect to perform either a qualitative assessment or to bypass the qualitative assessment and perform a quantitative test.

Ameren and Ameren Illinois elected to perform a qualitative assessment for their annual goodwill impairment test conducted as of October 31, 2025. As part of this qualitative assessment, Ameren and Ameren Illinois evaluated, among other things, macroeconomic conditions, industry and market considerations such as observable industry market multiples, regulatory frameworks, cost factors, overall financial performance, and entity-specific events. The results of Ameren’s and Ameren Illinois’ qualitative assessment indicated that it was more likely than not that the fair value of each reporting unit exceeded its carrying value as of October 31, 2025, resulting in no impairment of Ameren’s or Ameren Illinois’ goodwill.

Variable Interest Entities

Variable Interest Entities that are Consolidated

AMF was formed in 2024, for the purpose of issuing and servicing securitized utility tariff bonds related to costs for the accelerated retirement of the Rush Island Energy Center. Ameren Missouri is the primary beneficiary of this entity because it has the power to direct the activities that most significantly impact the economic performance of the entity, as well as the obligation to absorb losses or the right to receive benefits from the entity. The entity is considered a variable interest entity primarily because its equity capitalization is insufficient to support its operations. The entity’s primary assets and liabilities are comprised of regulatory assets related to the unrecovered net plant balance associated with the retired energy center, among other costs, and long-term debt. Ameren and Ameren Missouri consolidate AMF, which Ameren Missouri wholly owns, and both manages and controls the entity’s operating activities. For additional information on the securitization of the Rush Island Energy Center costs, see Note 2 – Rate and Regulatory Matters. For additional information on the securitized tariff bond issuance, see Note 5 – Long-term Debt and Equity Financings.

The following table presents the carrying values of AMF’s assets and liabilities included on Ameren’s and Ameren Missouri’s consolidated balance sheets as of December 31, 2025 :


	2025		2024
Unbilled revenue (a)	$	2	$	—
Other current assets(a)(b)	21		2
Noncurrent regulatory assets(a)	443		465
Current maturities of long term debt(c)	23		17
Interest accrued (c)	6		1
Current regulatory liabilities(d)	11		—
Long-term debt, net(c)	426		448

(a)Assets may be used only to meet AMF’s obligations and commitments.

(b)Included in “Restricted cash” on Ameren Missouri’s balance sheet.

(c)The securitized tariff bondholders have no recourse to Ameren Missouri.

(d)Included in “Other current liabilities” on Ameren Missouri’s balance sheet.

Variable Interest Entities that are not Consolidated

As of December 31, 2025 and 2024, Ameren had unconsolidated variable interests in various equity method investments, primarily to advance innovative energy technologies, totaling $64 million and $74 million, respectively, included in “Other assets” on Ameren’s consolidated balance sheet. Any earnings or losses related to these investments are included in “Other Income, Net” on Ameren’s consolidated statement of income and comprehensive income. Ameren is not the primary beneficiary of these investments because it does not have the power to direct matters that most significantly affect the activities of these variable interest entities. As of December 31, 2025, the maximum exposure to loss related to these variable interest entities is limited to the investment in these partnerships of $64 million plus associated outstanding funding commitments of $28 million.

Asset Retirement Obligations

Asset Retirement Obligations and Removal Costs

We record the estimated fair value of legal obligations associated with the retirement of tangible long-lived assets in the period in which the liabilities are incurred and capitalize a corresponding amount as part of the book value of the related long-lived asset. In subsequent periods, we adjust AROs for accretion and changes in the estimated fair values of the obligations, with a corresponding increase or decrease in the asset book value for the fair value changes. Asset book values, reflected within “Property, Plant, and Equipment, Net” on the balance sheet, are depreciated over the remaining useful life of the related asset. Depreciation is deferred as a regulatory balance. The depreciation of the asset book values at Ameren Missouri was $7 million, $2 million, and $9 million for the years ended December 31, 2025, 2024, and 2023, respectively, which was deferred as a reduction to the net regulatory liability. The net regulatory liability also reflects a deferral for the nuclear decommissioning trust fund balance for the Callaway Energy Center. The depreciation deferred to the regulatory asset at Ameren Illinois was immaterial in each respective period. Uncertainties as to the probability, timing, or amount of cash expenditures associated with AROs affect our estimates of fair value. Ameren and Ameren Missouri have recorded AROs for retirement costs associated with decommissioning of Ameren Missouri’s Callaway and wind renewable energy centers, certain Ameren Missouri solar energy centers, CCR facilities, and river structures at certain energy centers used for unloading coal and circulating water systems. Additionally, Ameren, Ameren Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal and the disposal of certain transformers. See Note 15 – Supplemental Information for a reconciliation of the beginning and ending carrying amounts of AROs.

Estimated funds collected from customers to pay for the future removal cost of property, plant, and equipment retired from service, represent a cost of removal regulatory liability. See the cost of removal regulatory liability balance in Note 2 – Rate and Regulatory Matters.

Company-owned Life Insurance

COLI

Ameren (parent) and Ameren Illinois have COLI, which is recorded at the net cash surrender value. The net cash surrender value is the amount that can be realized under the insurance policies at the balance sheet date. As of December 31, 2025, the cash surrender value of COLI at Ameren and Ameren Illinois was $219 million (December 31, 2024 – $260 million) and $126 million (December 31, 2024 – $118 million), respectively, while total borrowings against the policies were $117 million (December 31, 2024 – $110 million) at both Ameren and Ameren Illinois. Ameren and Ameren Illinois have the right to offset the borrowings against the cash surrender value of the policies and,

consequently, present the net asset in “Other assets” on their respective balance sheets. The net cash surrender value of Ameren’s COLI is affected by the investment performance of a separate account in which Ameren holds a beneficial interest.

Operating Revenues

We record revenues from contracts with customers for various electric and natural gas services, which primarily consist of retail distribution, electric transmission, and off-system arrangements. When more than one performance obligation exists in a contract, the consideration under the contract is allocated to the performance obligations based on the relative standalone selling price.

Electric and natural gas retail distribution revenues are earned when the commodity is delivered to our customers. We accrue an estimate of electric and natural gas retail distribution revenues for service provided but unbilled at the end of each accounting period. Electric transmission revenues are earned as electric transmission services are provided. Off-system revenues are primarily comprised of MISO revenues and wholesale bilateral revenues. MISO revenues include the sale of electricity, capacity, and ancillary services. Wholesale bilateral revenues include the sale of electricity and capacity. MISO-related electricity and wholesale bilateral electricity revenues are earned as electricity is delivered. Capacity and ancillary service revenues are earned as services are provided.

Retail distribution, electric transmission, and off-system revenues, including the underlying components described above, represent a series of goods or services that are substantially the same and have the same pattern of transfer over time to our customers. Revenues from contracts with customers are equal to the amounts billed and our estimate of electric and natural gas retail distribution services provided but unbilled at the end of each accounting period. Customers are billed at least monthly, and payments are due less than one month after goods and/or services are provided. See Note 16 – Segment Information for disaggregated revenue information.

For certain regulatory recovery mechanisms that are alternative revenue programs rather than revenues from contracts with customers, we recognize revenues that have been authorized for rate recovery, are objectively determinable and probable of recovery, and are expected to be collected from customers within two years from the end of the year. Our alternative revenue programs include revenue requirement reconciliations, the MEEIA, the RBA, the VBA, and the WNAR. These revenues are subsequently recognized as revenues from contracts with customers when billed, with an offset to alternative revenue program revenues.

As of December 31, 2025 and 2024, our remaining performance obligations were immaterial. The Ameren Companies elected not to disclose the aggregate amount of the transaction price allocated to the performance obligations that are unsatisfied as of the end of the reporting period for contracts with an initial expected term of one year or less.

Cost Of Sales

Accounting for MISO Transactions

MISO-related purchase and sale transactions are recorded by Ameren, Ameren Missouri, and Ameren Illinois using settlement information provided by the MISO. Ameren Missouri records these purchase and sale transactions on a net hourly position. Ameren Missouri records net purchases in a single hour in “Operating Expenses – Fuel and purchased power” and net sales in a single hour in “Operating Revenues – Electric” in its statement of income. Ameren Illinois records net purchases in “Operating Expenses – Fuel and purchased power” in its statement of income to reflect all of its MISO transactions relating to the procurement of power for its customers.

Stock-Based Compensation

Stock-based Compensation

Stock-based compensation cost is measured at the grant date based on the fair value of the award, net of an assumed forfeiture rate. Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite vesting period. To the extent that actual forfeitures differ from estimated forfeitures, such differences are accounted for as an adjustment to compensation expense and recorded in the period that estimates are revised. Compensation cost is ultimately recognized only for awards for which the requisite service was provided. See Note 11 – Stock-based Compensation for additional information.

Unamortized Debt Discount, Premium, And Expense

Unamortized Debt Discounts, Premiums, and Issuance Costs

Long-term debt discounts, premiums, and issuance costs are amortized over the lives of the related issuances. Credit agreement fees are amortized over the term of the agreement.

Income Taxes

Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes. Deferred tax assets and liabilities are recognized for transactions that are treated differently for financial reporting and income tax return purposes. These deferred tax assets and liabilities are based on statutory tax rates.

We expect that regulators will reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate. Therefore, reductions in certain excess deferred tax liabilities that were recorded because of decreases in the statutory

rate have been credited to a regulatory liability. A regulatory asset has been established to recognize the probable recovery through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate increases. To the extent deferred tax balances are included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as a regulatory asset or liability on the balance sheet and will be collected from, or refunded to, customers. For deferred tax balances not included in rate base, the revaluation of deferred taxes caused by a change in the statutory rate is recorded as an adjustment to income tax expense on the income statement.

Tax credits other than investment tax credits are recognized as a reduction to income tax expense when earned and realizable. The benefits for investment tax credits not transferred under the IRA are amortized over the book depreciable lives of the related property. For production and other tax credits otherwise eligible to be recognized when earned and for investment tax credits transferred under the IRA, Ameren considers the impact of rate regulation to determine if these credits and related adjustments should be deferred as regulatory liabilities. See Note 2 – Rate and Regulatory Matters for additional information on Ameren Missouri’s production and investment tax credit tracker and the RESRAM.

Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren (parent) that provides for the allocation of consolidated tax liabilities. The tax allocation agreement specifies that each subsidiary be allocated an amount of tax using a stand-alone calculation ratio to the total amount of tax owed by the consolidated group. Any net benefit attributable to Ameren (parent) is reallocated to the other subsidiaries. This reallocation is treated as a capital contribution to the subsidiary receiving the benefit. See Note 13 – Related-party Transactions for information regarding capital contributions under the tax allocation agreement.

Internal Use Software, Policy

Improvements to the Accounting for Internal-Use Software

In September 2025, the FASB issued authoritative guidance that made targeted improvements to the accounting for internal-use software. The guidance requires an entity to capitalize internal-use software costs when management has authorized and committed to funding the software project, and it is probable that the project will be completed and the software will be used to perform its intended function. This guidance will be effective for the Ameren Companies in the first quarter of 2028. We are currently assessing the impacts of this guidance on our results of operations, financial position, and liquidity.

Government Assistance

Accounting for Government Grants Received by Business Entities

In December 2025, the FASB issued authoritative guidance that established requirements for the recognition, measurement, presentation, and disclosure of government grants received by business entities. The guidance applies to transfers of monetary or tangible nonmonetary assets from a government to a business entity, excluding income tax credits, below-market loans, and government guarantees. Under this guidance, government grants are recognized when it is probable that a business entity will comply with the grant’s conditions and will receive the grant. This guidance will be effective for the Ameren Companies in the first quarter of 2029. We are currently assessing the impacts of this guidance on our results of operations, financial position, and liquidity.

Noncontrolling Interests

The preferred stock of Ameren’s subsidiaries is included in “Noncontrolling Interests” on Ameren’s consolidated balance sheet

Derivatives, Policy

We use derivatives to manage the risk of changes in market prices for natural gas, power, and interest rates, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. Such price fluctuations may cause the following:

•an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;

•market values of natural gas that differ from the cost of this commodity in inventory;

•actual cash outlays for interest expense and the purchase of commodities that differ from anticipated cash outlays; and

•actual off-system sales revenues that differ from anticipated revenues.

The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.

The Ameren Companies elect to present the fair value amounts of derivative assets and derivative liabilities subject to an enforceable master netting arrangement or similar agreement at the gross amounts on the balance sheet. However, if the gross amounts recognized on the balance sheet were netted with derivative instruments and cash collateral received or posted, the net amounts would not be materially different from the gross amounts at December 31, 2025 and 2024.

Lessee, Leases

Leases

Ameren and Ameren Missouri have lease agreements primarily relating to rail cars and land related to solar generation facilities. The land leases are related to the Cass County, Boomtown, and Huck Finn energy centers. Rail cars are leased for the transportation of coal to its energy centers. For rail car leases, we account for the lease and non-lease components as a single lease component, and for the land leases related to solar generation projects, we account for the components separately for each agreement. Certain of the land leases related to the acquisitions of the Cass County, Boomtown, and Huck Finn energy centers have options to renew or terminate those leases. Termination and renewal options are not expected to be exercised and are not included in any of the lease measurements used to record the leased assets and liabilities in the tables below.

Excise Taxes

Ameren Missouri and Ameren Illinois collect from their customers excise taxes, including municipal and state excise taxes and gross receipts taxes, that are levied on the sale or distribution of natural gas and electricity.

Earnings Per Share, Policy

Earnings per Share

Earnings per basic and diluted share are computed by dividing “Net Income Attributable to Ameren Common Shareholders” by the weighted-average number of basic and diluted common shares outstanding, respectively, during the applicable period. The weighted-average shares outstanding for earnings per diluted share includes the incremental effects resulting from performance share units, restricted stock units, and forward sale agreements relating to common stock when the impact would be dilutive, as calculated using the treasury stock method.

Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2025

Accounting Policies [Abstract]

Schedule of Other Assets and Other Liabilities

The following table presents the carrying values of AMF’s assets and liabilities included on Ameren’s and Ameren Missouri’s consolidated balance sheets as of December 31, 2025 :


	2025		2024
Unbilled revenue (a)	$	2	$	—
Other current assets(a)(b)	21		2
Noncurrent regulatory assets(a)	443		465
Current maturities of long term debt(c)	23		17
Interest accrued (c)	6		1
Current regulatory liabilities(d)	11		—
Long-term debt, net(c)	426		448

(a)Assets may be used only to meet AMF’s obligations and commitments.

(b)Included in “Restricted cash” on Ameren Missouri’s balance sheet.

(c)The securitized tariff bondholders have no recourse to Ameren Missouri.

(d)Included in “Other current liabilities” on Ameren Missouri’s balance sheet.

Rate And Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2025

Public Utilities, General Disclosures [Abstract]

Schedule of Regulatory Frameworks and Significant Recovery Mechanisms

The following table presents the regulatory frameworks and significant regulatory recovery mechanisms for each of Ameren’s rate-regulated businesses, which are discussed in more detail below:

Ameren Missouri

Ameren Illinois’ electric distribution business

Ameren Illinois’ natural gas delivery business

Ameren Illinois’ and ATXI’s electric transmission businesses

Regulatory framework

•Historical test year ratemaking

•Natural gas revenues for residential customers adjusted for sales volume deviations resulting from weather through the WNAR

•MYRP

•Initial rates based on future test years

•Revenues decoupled from sales volumes and wholesale and miscellaneous revenues through the RBA

•Future test year ratemaking

•Revenues for residential and small nonresidential customers decoupled from sales volumes through the VBA

•Formula ratemaking

•Initial rates based on future test year

•Revenues decoupled from sales volumes

Regulatory mechanisms

•PISA

Riders:

•RESRAM

•FAC

•Rush Island securitization

•MEEIA

•PGA

•WNAR

Trackers:

•Pension and postretirement benefit costs

•Certain excess deferred income taxes

•Property taxes

•Production and investment tax credits or proceeds from the sale of certain tax credits allowed under the IRA

•Renewable solutions program revenues and costs(a)

•Electric distribution service and energy-efficiency revenue requirement reconciliation adjustments(b)

Riders:

•RBA

•Power procurement

•Transmission services

•Renewable energy credit compliance

•Zero emission credits

•Customer generation rebate program costs

•Certain environmental costs

•Bad debt write-offs

•Costs of certain asbestos-related claims

Riders:

•PGA

•VBA

•Energy-efficiency program costs

•Certain environmental costs

•Bad debt write-offs

•Invested capital taxes

•Revenue requirement reconciliation adjustment

(a)Ameren Missouri’s renewable solutions program allows certain commercial, industrial, and governmental customers who enroll in the program to receive up to 100% of their energy from renewable resources.

(b)Reconciliation adjustments under an MYRP are subject to a reconciliation cap which limits annual adjustment to 105%. See below for additional information regarding the reconciliation cap.

Schedule of Energy Center Projects

The following table provides information with respect to each facility:

Agreement type

Facility size

Status of MoPSC CCN

In-service date(a)

Vandalia Solar Project(b)

Self-build

50-MW

Approved March 2024

December 2025

Bowling Green Solar Project(b)

Self-build

50-MW

Approved March 2024

First quarter 2026

Split Rail Solar Project

Build-transfer(c)

300-MW

Approved March 2024

Second quarter 2026

Castle Bluff Natural Gas Project(d)

Self-build

800-MW

Approved October 2024

Fourth quarter 2027

Big Hollow Battery Energy Storage Project(e)

Self-build

400-MW

Approved February 2026

Second quarter 2028

Big Hollow Natural Gas Project(e)

Self-build

800-MW

Approved February 2026

Third quarter 2028

Reform Solar Project

Self-build

250-MW

Filed August 2025(f)

Fourth quarter 2028

(a)In-service dates are dependent on the timing of regulatory approvals and construction completion, among other things.

(b)These projects collectively represent approximately $0.2 billion of capital expenditures.

(c)Ameren Missouri received FERC approval for the acquisition in November 2024. In February 2026, Ameren Missouri acquired the Split Rail Solar Project, which includes solar panels, project design, land rights, and engineering, procurement, and construction agreements, for approximately $0.6 billion, and took over construction management of the project.

(d)This project represents approximately $0.9 billion of capital expenditures.

(e)These projects represent approximately $2 billion of capital expenditures.

(f)Ameren Missouri expects a decision by the MoPSC in the first half of 2026.

Schedule Of Regulatory Assets And Liabilities

The following table presents our regulatory assets and regulatory liabilities at December 31, 2025 and 2024:


	2025						2024
	Ameren Missouri		Ameren Illinois		Ameren		Ameren Missouri		Ameren Illinois		Ameren
Regulatory assets:
Under-recovered FAC(a)	$	137	$	—	$	137	$	41	$	—	$	41


MTM derivative losses(b)	15		111		126		15		88		103

IEIMA revenue requirement reconciliation adjustment(c)(d)	—		—		—		—		139		139
MYRP revenue requirement reconciliation adjustment(d)(e)	—		74		74		—		24		24
Under-recovered RBA(f)	—		29		29		—		22		22
FERC revenue requirement reconciliation adjustment(g)	—		45		73		—		55		90
Under-recovered VBA(h)	—		21		21		—		49		49

Income taxes(i)	282		91		376		237		81		322


Bad debt rider(j)	—		13		13		—		25		25

Callaway refueling and maintenance outage costs(k)	32		—		32		13		—		13
Unamortized loss on reacquired debt(l)	40		4		44		42		5		47
Environmental cost riders(m)	—		46		46		—		43		43
Storm costs(d)(n)	—		15		15		—		18		18





Customer generation rebate program(d)(o)	—		141		141		—		89		89


PISA(d)(p)	558		—		558		464		—		464
Rush Island Energy Center securitization(q)	443		—		443		465		—		465
RESRAM(r)	44		—		44		51		—		51
Certain Meramec Energy Center costs(s)	14		—		14		26		—		26
Energy-efficiency rider(d)(t)	—		624		624		—		576		576
Property tax tracker(u)	18		—		18		22		—		22

Other	48		34		83		56		78		134
Total regulatory assets	$	1,631	$	1,248	$	2,911	$	1,432	$	1,292	$	2,763
Less: current regulatory assets	(181)		(189)		(387)		(66)		(281)		(366)
Noncurrent regulatory assets	$	1,450	$	1,059	$	2,524	$	1,366	$	1,011	$	2,397
Regulatory liabilities:

Over-recovered Illinois electric power costs(v)	—		85		85		—		34		34
Over-recovered PGA(v)	3		39		42		2		33		35

MTM derivative gains(b)	12		4		16		10		6		16





Income taxes(i)	963		546		1,587		1,040		679		1,804



Cost of removal(w)	1,203		1,230		2,511		1,118		1,115		2,294
AROs(x)	841		—		841		691		—		691


Pension and postretirement benefit costs(y)	230		237		467		202		156		358
Pension and postretirement benefit costs tracker(z)	9		—		9		70		—		70


Renewable energy credits and zero emission credits(aa)	—		699		699		—		586		586



Certain Rush Island Energy Center costs(ab)	31		—		31		66		—		66
Rush Island Energy Center base rate revenue deferral(ac)	31		—		31		13		—		13
Other	24		67		94		1		43		50
Total regulatory liabilities	$	3,347	$	2,907	$	6,413	$	3,213	$	2,652	$	6,017
Less: current regulatory liabilities	(23)		(132)		(158)		(37)		(79)		(120)
Noncurrent regulatory liabilities	$	3,324	$	2,775	$	6,255	$	3,176	$	2,573	$	5,897