AMENTUM HOLDINGS, INC., 10-Q filed on 5/7/2025
Quarterly Report
v3.25.1
Cover - shares
 6 Months Ended
Mar. 28, 2025
May 02, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 28, 2025  
Document Transition Report false  
Entity File Number 001-42176  
Registrant Name Amentum Holdings, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 99-0622272  
Entity Address, Address Line One 4800 Westfields Blvd., Suite #400  
Entity Address, City or Town Chantilly  
Entity Address, State or Province VA  
Entity Address, Postal Zip Code 20151  
City Area Code 703  
Local Phone Number 579-0410  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Trading Symbol AMTM  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   243,322,468
Entity Central Index Key 0002011286  
Amendment Flag false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Current Fiscal Year End Date --10-03  
v3.25.1
CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Millions
Mar. 28, 2025
Sep. 27, 2024
Current assets:    
Cash and cash equivalents $ 546 $ 452
Accounts receivable, net 2,509 2,401
Prepaid expenses and other current assets 211 231
Total current assets 3,266 3,084
Property and equipment, net 133 144
Equity method investments 193 123
Goodwill 5,658 5,556
Intangible assets, net 2,353 2,623
Other long-term assets 401 444
Total assets 12,004 11,974
Current liabilities:    
Current portion of long-term debt 43 36
Accounts payable 876 764
Accrued compensation and benefits 659 696
Contract liabilities 112 113
Other current liabilities 407 356
Total current liabilities 2,097 1,965
Long-term debt, net of current portion 4,636 4,643
Deferred tax liabilities 332 370
Other long-term liabilities 360 444
Total liabilities 7,425 7,422
Commitments and contingencies (Note 14)
SHAREHOLDERS' EQUITY    
Common stock, $0.01 par value, 1,000,000,000 shares authorized; 243,322,468 shares issued and outstanding at March 28, 2025 and 243,302,173 shares issued and outstanding at September 27, 2024. 2 2
Additional paid-in capital 4,907 4,962
Retained deficit (511) (527)
Accumulated other comprehensive income 29 23
Total Amentum shareholders' equity 4,427 4,460
Non-controlling interests 152 92
Total shareholders' equity 4,579 4,552
Total liabilities and shareholders' equity $ 12,004 $ 11,974
v3.25.1
CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares
Mar. 28, 2025
Sep. 27, 2024
Statement of Financial Position [Abstract]    
Common stock, par value (in dollars per share) $ 0.01 $ 0.01
Common stock, shares authorized (in shares) 1,000,000,000 1,000,000,000
Common stock, issued (in shares) 243,322,468 243,302,173
Common stock, outstanding (in shares) 243,322,468 243,302,173
v3.25.1
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Income Statement [Abstract]        
Revenues $ 3,491 $ 2,051 $ 6,907 $ 4,034
Cost of revenues (3,124) (1,851) (6,179) (3,640)
Selling, general, and administrative expenses (145) (72) (275) (139)
Amortization of intangibles (120) (58) (240) (114)
Equity earnings of non-consolidated subsidiaries 8 19 29 34
Operating income 110 89 242 175
Interest expense and other, net (86) (111) (173) (222)
Income (loss) before income taxes 24 (22) 69 (47)
Provision for income taxes (22) (20) (46) (34)
Net income (loss) including non-controlling interests 2 (42) 23 (81)
Less: net income (loss) attributable to non-controlling interests 2 1 (7) (1)
Net income (loss) attributable to common shareholders $ 4 $ (41) $ 16 $ (82)
Earnings (loss) per share:        
Basic (in dollars per share) $ 0.02 $ (0.46) $ 0.07 $ (0.91)
Diluted (in dollars per share) $ 0.02 $ (0.46) $ 0.07 $ (0.91)
v3.25.1
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Statement of Comprehensive Income [Abstract]        
Net income (loss) including non-controlling interests $ 2 $ (42) $ 23 $ (81)
Other comprehensive income (loss):        
Net unrealized (loss) gain on interest rate swaps (7) 15 15 (14)
Foreign currency translation adjustments 11 (2) (7) 4
Pension adjustments 0 (1) 0 (1)
Other comprehensive income (loss) 4 12 8 (11)
Income tax benefit (provision) related to items of other comprehensive income (loss) 2 (2) (2) 2
Other comprehensive income (loss), net of tax 6 10 6 (9)
Comprehensive income (loss) 8 (32) 29 (90)
Net income (loss) attributable to non-controlling interests 2 1 (7) (1)
Comprehensive income (loss) attributable to common shareholders $ 10 $ (31) $ 22 $ (91)
v3.25.1
CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($)
$ in Millions
Total
Total Shareholders' Equity Attributable to Amentum Holdings, Inc.
Common Stock
Additional Paid-in Capital
Retained Deficit
Accumulated Other Comprehensive Income
Non-controlling Interests
Beginning balance at Sep. 29, 2023 $ 416 $ 375   $ 772 $ (445) $ 48 $ 41
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income (loss) including non-controlling interests (81) (82)     (82)   1
Other comprehensive income (loss), net of tax (9) (9)       (9)  
Distributions to non-controlling interests (2)           (2)
Equity based compensation and other 0 4   4     (4)
Ending balance at Mar. 29, 2024 324 288   776 (527) 39 36
Beginning balance at Dec. 29, 2023 358 318   775 (486) 29 40
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income (loss) including non-controlling interests (42) (41)     (41)   (1)
Other comprehensive income (loss), net of tax 10 10       10  
Distributions to non-controlling interests (2)           (2)
Equity based compensation and other 0 1   1     (1)
Ending balance at Mar. 29, 2024 $ 324 288   776 (527) 39 36
Beginning balance (in shares) at Sep. 27, 2024 243,302,173   243,000,000        
Beginning balance at Sep. 27, 2024 $ 4,552 4,460 $ 2 4,962 (527) 23 92
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income (loss) including non-controlling interests 23 16     16   7
Other comprehensive income (loss), net of tax 6 6       6  
Measurement period adjustments 12 (63)   (63)     75
Distributions to non-controlling interests (22)           (22)
Equity based compensation and other $ 8 8   8     0
Ending balance (in shares) at Mar. 28, 2025 243,322,468   243,000,000        
Ending balance at Mar. 28, 2025 $ 4,579 4,427 $ 2 4,907 (511) 29 152
Beginning balance (in shares) at Dec. 27, 2024     243,000,000        
Beginning balance at Dec. 27, 2024 4,563 4,475 $ 2 4,965 (515) 23 88
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income (loss) including non-controlling interests 2 4     4   (2)
Other comprehensive income (loss), net of tax 6 6       6  
Measurement period adjustments 12 (63)   (63)     75
Distributions to non-controlling interests (9)           (9)
Equity based compensation and other $ 5 5   5      
Ending balance (in shares) at Mar. 28, 2025 243,322,468   243,000,000        
Ending balance at Mar. 28, 2025 $ 4,579 $ 4,427 $ 2 $ 4,907 $ (511) $ 29 $ 152
v3.25.1
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Millions
 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Cash flows from operating activities    
Net income (loss) including non-controlling interests $ 23 $ (81)
Adjustments to reconcile net income (loss) including non-controlling interests to net cash provided by (used in) operating activities:    
Depreciation 18 12
Amortization of intangibles 240 114
Amortization of deferred loan costs and original issue discount 5 11
Derivative instruments 6 31
Equity earnings of non-consolidated subsidiaries (29) (34)
Distributions from equity method investments 35 31
Deferred income taxes (11) (29)
Equity-based compensation 8 2
Other (1) 2
Changes in assets and liabilities, net of effects of business acquisition:    
Accounts receivable, net (127) (88)
Prepaid expenses and other assets 71 52
Accounts payable, contract liabilities, and other current liabilities (11) (98)
Accrued employee compensation and benefits (46) (4)
Other long-term liabilities (14) 1
Net cash provided by (used in) operating activities 167 (78)
Cash flows from investing activities    
Payments for property and equipment (12) (5)
Contributions to equity method investments (28) 0
Other 1 (1)
Net cash used in investing activities (39) (6)
Cash flows from financing activities    
Borrowings on revolving credit facilities 513 562
Payments on revolving credit facilities (513) (562)
Repayments of borrowings under the credit agreement 0 (17)
Repayments of borrowings under other agreements (5) (6)
Distributions to non-controlling interests (22) (2)
Other (1) (3)
Net cash used in financing activities (28) (28)
Effect of exchange rate changes on cash (6) 4
Net change in cash and cash equivalents 94 (108)
Cash and cash equivalents, beginning of period 452 305
Cash and cash equivalents, end of period 546 197
Supplemental disclosure of cash flow information    
Common stock issued for the Transaction (63) 0
Accrued acquisition working capital settlement 70 0
Income taxes paid, net of receipts (40) (28)
Interest paid $ (133) $ (185)
v3.25.1
Basis of Presentation
 6 Months Ended
Mar. 28, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Basis of Presentation Basis of Presentation
Amentum Holdings, Inc. (collectively with its subsidiaries, “we,” “us,” “our,” “Amentum,” or the “Company”) is a global advanced engineering and technology solutions provider to a broad base of U.S. and allied government agencies, supporting programs of critical national importance across energy and environmental, intelligence, space, defense, civilian and commercial end-markets. We offer a broad reach of capabilities including intelligence and counter threat solutions, data fusion and analytics, engineering and integration, environmental solutions, advanced test, training and readiness, and citizen solutions. As a leading provider of differentiated technology solutions, we have built a repertoire of deep customer knowledge, enabling us to engage our customers across multiple capabilities and markets.
During the first quarter of fiscal year 2025, we announced the realignment of our reporting structure, which resulted in the identification of two reportable segments: Digital Solutions (“DS”) and Global Engineering Solutions (“GES”). The DS segment provides advanced digital and data-driven solutions including intelligence analytics, space system development, cybersecurity, and next generation IT across the federal government and commercial clients. The GES segment provides large-scale environmental remediation, clean energy, platform engineering, sustainment and supply chain management across all seven continents for the U.S. government and allied nations. As a result of this change, prior year segment disclosures have been recast to reflect the current reportable segment structure.
On September 27, 2024, the spin-off of the Jacobs Solutions Inc. (“Jacobs”) Critical Mission Solutions business and portions of the Jacobs Divergent Solutions business (and, together with the Critical Mission Solutions business, referred to as the “CMS Business” or “CMS”) merged with Amentum Parent Holdings LLC (collectively, the “Transaction”) with the surviving entity renamed Amentum Holdings, Inc.
Amentum Parent Holdings LLC is considered the Company’s predecessor, and the historical financial statements of Amentum Parent Holdings LLC prior to September 27, 2024 are reflected in this Quarterly Report on Form 10-Q as the Company’s historical financial statements. Accordingly, the financial results of the Company prior to September 27, 2024 do not include the financial results of CMS, and current and future results will not be comparable to historical results.
The accompanying unaudited condensed consolidated financial statements of the Company include the assets, liabilities, results of operations, comprehensive income (loss) and cash flows for the Company, including its wholly-owned subsidiaries and joint ventures that are majority-owned or otherwise controlled by the Company. Certain information and note disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted, although the Company believes that the disclosures made are adequate to make the information presented not misleading. All intercompany transactions and balances have been eliminated in consolidation.
In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments and reclassifications (all of which are of a normal, recurring nature) that are necessary for the fair presentation of the periods presented. It is suggested that these unaudited condensed consolidated financial statements be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s latest annual report for the fiscal year ended September 27, 2024. The results of operations for the three and six months ended March 28, 2025 are not necessarily indicative of the results to be expected for any subsequent interim period or for the full fiscal year.
v3.25.1
Recent Accounting Pronouncements
 6 Months Ended
Mar. 28, 2025
Accounting Policies [Abstract]  
Recent Accounting Pronouncements Recent Accounting Pronouncements
Accounting Standards Updates Issued but Not Yet Adopted

In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, to improve reportable segment disclosure requirements. This update requires disclosure of significant segment expenses and other segment items in annual and interim periods. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. The amendment requires retrospective application to all prior periods presented in the financial statements, and early adoption is permitted. We are currently evaluating the impacts of the new standard on our consolidated financial statements.
In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, to enhance transparency and usefulness of income tax disclosures. This update requires disaggregated information about an entity’s effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, and may be applied on a prospective or retrospective basis. Early adoption is permitted. We are currently evaluating the impacts of the new standard on our financial statement disclosures.
v3.25.1
Acquisitions
 6 Months Ended
Mar. 28, 2025
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]  
Acquisitions Acquisition
On September 27, 2024, the Company completed its merger with CMS, a leading provider of mission-critical, technology-driven services in government and commercial markets, in a Reverse Morris Trust transaction. Immediately following the Transaction, the Company had approximately 243 million issued and outstanding shares of common stock, of which Jacobs and its shareholders (“CMS Shareholders”) owned 58.5% of the issued and outstanding shares of common stock, and Amentum Joint Venture LP, our previous parent company (“AJVLP” and “Amentum Equityholder”) owned 37.0%. Subsequently, Amentum Equityholder distributed its shares of our common stock to certain parties (collectively, “Sponsor Stockholder”). Further, 4.5% of the issued and outstanding shares of common stock was placed in escrow at the merger date, to be released and delivered in the future to CMS Shareholders or to Amentum Equityholder, depending on the achievement of certain fiscal year 2024 targets by the CMS Business (“Additional Merger Consideration”). In March 2025, the Company and Jacobs finalized the Additional Merger Consideration and released all 4.5% of the issued and outstanding shares of common stock out of escrow with 3.5% of the issued and outstanding shares released to CMS Shareholders and the remaining 1.0% of issued and outstanding shares to the Sponsor Stockholder.
Under the acquisition method of accounting, total consideration exchanged for the CMS transaction is shown below and increased $7 million from September 27, 2024:
(In millions, except per share amounts)
Shares of Amentum Holdings, Inc. common stock issued to CMS shareholders142 
Per share price of Amentum Holdings, Inc. common stock25.67 
Fair value of common stock issued to CMS shareholders (1)
3,654 
Fair value of additional equity consideration issued to CMS shareholders (2)
218 
Final working capital settlement (3)
70 
Other consideration (4)
6 
Fair value of consideration transferred3,948 
Fair value of previously held equity interest (5)
84 
Total consideration$4,032 
(1)    Represents the fair value of equity consideration received by CMS Shareholders to provide 58.5% ownership in the Company.
(2)    Represents the Additional Equity Consideration which was finalized in March 2025. The balance reflects a decrease in equity consideration issued to CMS Shareholders following a resolution to release an additional 1.0% of the issued and outstanding shares of Amentum common stock back to Sponsor Stockholder. This balance is presented at fair value based on the acquisition-date share price and is included in the total purchase consideration in accordance with ASC 805.
(3)    Reflects a $70 million cash payment made based on the final net working capital position. This payment was made in the third quarter of fiscal year 2025 and is included in the total purchase consideration in accordance with ASC 805, as it represents an obligation attributable to pre-acquisition activities.
(4)    Represents other immaterial adjustments, including a) estimated equity consideration related to pre-combination share-based compensation awards, b) the settlement of CMS transaction costs paid by Amentum, and c) the removal of consideration related to the acquisition of non-controlling interests.
    
(5)    Prior to the Transaction, we held a non-controlling interest in a joint venture of 50% which was accounted for under the equity method of accounting, with the remaining 40% held by the CMS Business and 10% held by an unrelated third party. As a result of the Transaction, the Company gained a controlling financial interest in the joint venture and it became a consolidated joint venture of the Company. This joint venture acquisition was accounted for as a business combination achieved in stages. Our pre-existing equity method investment in the joint venture was remeasured at an acquisition date fair value of $170 million by using a discounted cash flow model based on estimated future revenues, margins and discount rates, among other variables and estimates. Additionally, as of the acquisition date, the Company had a payable to the joint venture with a fair value of $1 million that was settled in connection with the acquisition.
The Transaction was accounted for as a business combination. The Company assessed the fair value of the identifiable intangible assets including customer relationships and backlog, which were valued using the excess earnings method of the income approach. This method requires several judgments and assumptions to determine the fair value of the intangible assets including expected future cash flows, weighted-average cost of capital, discount rates, useful lives of assets and expected long-term growth rates. The goodwill recognized was attributable to the synergies expected to be achieved by combining the businesses of Amentum and CMS, expected future contracts and the acquired workforce. The goodwill is partially deductible for tax purposes.
The purchase price was allocated, on a preliminary basis, to the tangible and intangible assets acquired and liabilities assumed based on their estimated fair values as of the acquisition date, with the excess purchase consideration recorded as goodwill. The Company is still evaluating the determination of fair values allocated to various assets and liabilities, including, but not limited to, intangible assets, accounts receivable, other current assets, property and equipment, equity method investments and joint ventures, other long-term assets, income taxes, deferred taxes, accounts payables, other current liabilities, contract liabilities, other long-term liabilities, non-controlling interests and goodwill. The allocation of the purchase price is preliminary and subject to change as the Company continues to obtain and assess relevant information that existed as of the acquisition date, including but not limited to, information pertaining to CMS’ legal proceedings, reserves, income taxes, contracts with customers, and pre-acquisition contingencies. Additionally, in connection and in accordance with the terms of the Transaction, prior to the spin-off and Transaction, CMS provided a cash payment to Jacobs of approximately $911 million, after adjustments based on the levels of cash, debt and working capital in the CMS Business. The Company expects to have sufficient information available to resolve these items within one year of the CMS acquisition date.
The preliminary allocation of the purchase price is as follows:
(Amounts in millions)
Preliminary Allocation of Purchase PriceMeasurement Period Adjustments, NetPreliminary Adjusted Allocation of Purchase Price
Cash and cash equivalents$488 $— $488 
Accounts receivable1,043 (21)1,022 
Prepaid expenses and other current assets82 (5)77 
Property and equipment72 (2)70 
Equity method investments17 50 67 
Goodwill2,665 102 2,767 
Intangible assets1,860 (30)1,830 
Other long-term assets107 16 123 
Current portion of long-term debt(8)— (8)
Accounts payable(257)— (257)
Accrued compensation and benefits(285)— (285)
Contract liabilities(48)3 (45)
Other current liabilities(98)(42)(140)
Long-term debt, net of current portion(1,122)— (1,122)
Deferred tax liabilities(353)27 (326)
Other long-term liabilities(75)(16)(91)
Non-controlling interests(63)(75)(138)
Total consideration$4,025 $7 $4,032 
The estimated fair value of acquired backlog of $275 million is amortized on an accelerated basis over approximately 1 year and the estimated fair value of customer relationship intangible assets of $1,555 million is amortized on an accelerated basis over approximately 14 years. The fair value attributed to these intangible assets acquired was based on assumptions and other information compiled by management, including independent valuations that utilized established valuation techniques, and thus represents a Level 3 fair value measurement. The income approach was primarily used to value the intangible assets, consisting primarily of acquired program and contract intangibles and backlog. The income approach indicates value for an asset based on the present value of cash flow projected to be generated by the asset. Projected cash flow is discounted at a rate of return that reflects the relative risk of achieving the cash flow and the time value of money.
v3.25.1
Revenues
 6 Months Ended
Mar. 28, 2025
Revenue from Contract with Customer [Abstract]  
Revenues Revenues
Disaggregation of Revenues
The Company disaggregates revenues by customer, contract type, prime contractor versus subcontractor, geographic location and whether the solution provided is primarily Digital Solutions or Global Engineering Solutions. These categories represent how the nature, amount, timing, and uncertainty of revenues and cash flows are affected.
Disaggregated revenues by customer-type were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Department of Defense and U.S. Intelligence Community$738 $1,070 $1,808 $354 $1,030 $1,384 
Other U.S. Government Agencies40558599095398493 
Commercial and International197496693 22152174
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Department of Defense and U.S. Intelligence Community$1,460 $2,116 $3,576 $705 $1,982 $2,687 
Other U.S. Government Agencies8211,185 2,006 182771953 
Commercial and International3459801,325 43351394
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Disaggregated revenues by contract-type were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Cost-plus-fee$861 $1,388 $2,249 $216 $1,052 $1,268 
Fixed-price331476807161388549 
Time-and-materials148287435 94140234 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Cost-plus-fee$1,646 $2,769 $4,415 $435 $2,087 $2,522 
Fixed-price6909481,638 3167421,058 
Time-and-materials290564854 179275454 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Disaggregated revenues by prime contractor versus subcontractor were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Prime contractor$1,215 $1,885 $3,100 $417 $1,410 $1,827 
Subcontractor125 266 391 54170224 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Prime contractor$2,379 $3,763 $6,142 $826 $2,761 $3,587 
Subcontractor247518765 104343447 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Revenues by geographic location are reported by the country in which the work is performed and were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
United States$1,285 $1,300 $2,585 $403 $1,120 $1,523 
International55851906 68 460 528 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
United States$2,507 $2,563 $5,070 $787 $2,183 $2,970 
International1191,718 1,837 143 921 1,064 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Changes in Estimates on Contracts
Changes in estimated contract earnings at completion using the cumulative catch-up method of accounting were recognized in revenues as follows:
Three Months EndedSix Months Ended
(Amounts in millions)
March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Favorable earnings at completion adjustments$48 $28 $68 $23 
Unfavorable earnings at completion adjustments(27)(9)(40)(7)
Net favorable adjustments$21 $19 $28 $16 
Impact on diluted earnings per share attributable to common shareholders (1)
$0.07 $0.17 $0.09 $0.14 
(1)    The impact on diluted loss per share attributable to common shareholders is calculated using our statutory rate.
Remaining Performance Obligations
As of March 28, 2025, we had a remaining performance obligations balance of $10.7 billion and expect to recognize approximately 72% and 87% of the remaining performance obligations balance as revenues over the next 12 and 24 months, respectively, with the remainder to be recognized thereafter.
Contract Balances
The Company's contract balances consisted of the following (in millions):
As of
Description of Contract Related BalanceClassificationMarch 28, 2025September 27, 2024
Billed and billable receivablesAccounts receivable, net$1,556 $1,378 
Contract assetsAccounts receivable, net910 986 
Related party receivablesAccounts receivable, net43 37 
Long-term contract assetsOther long-term assets138 138 
Contract liabilities - deferred revenues and other contract liabilitiesContract liabilities(112)(113)
Contract assets primarily relate to accruals for reimbursable costs and fees in which our right to consideration is conditional. Long-term contract assets relate to a prior acquisition and are discussed further in Note 14 — Legal Proceedings and Commitments and Contingencies.
The Company has related party receivables due from our equity method investments, discussed further in Note 10 — Joint Ventures.
During the three and six months ended March 28, 2025, we recognized revenues of $8 million and $73 million, respectively, compared with $6 million and $82 million of revenues during the three and six months ended March 29, 2024, respectively, that was included in Contract liabilities as of September 27, 2024 and September 29, 2023, respectively.
v3.25.1
Contract Balances
 6 Months Ended
Mar. 28, 2025
Revenue from Contract with Customer [Abstract]  
Contract Balances Revenues
Disaggregation of Revenues
The Company disaggregates revenues by customer, contract type, prime contractor versus subcontractor, geographic location and whether the solution provided is primarily Digital Solutions or Global Engineering Solutions. These categories represent how the nature, amount, timing, and uncertainty of revenues and cash flows are affected.
Disaggregated revenues by customer-type were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Department of Defense and U.S. Intelligence Community$738 $1,070 $1,808 $354 $1,030 $1,384 
Other U.S. Government Agencies40558599095398493 
Commercial and International197496693 22152174
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Department of Defense and U.S. Intelligence Community$1,460 $2,116 $3,576 $705 $1,982 $2,687 
Other U.S. Government Agencies8211,185 2,006 182771953 
Commercial and International3459801,325 43351394
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Disaggregated revenues by contract-type were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Cost-plus-fee$861 $1,388 $2,249 $216 $1,052 $1,268 
Fixed-price331476807161388549 
Time-and-materials148287435 94140234 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Cost-plus-fee$1,646 $2,769 $4,415 $435 $2,087 $2,522 
Fixed-price6909481,638 3167421,058 
Time-and-materials290564854 179275454 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Disaggregated revenues by prime contractor versus subcontractor were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Prime contractor$1,215 $1,885 $3,100 $417 $1,410 $1,827 
Subcontractor125 266 391 54170224 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Prime contractor$2,379 $3,763 $6,142 $826 $2,761 $3,587 
Subcontractor247518765 104343447 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Revenues by geographic location are reported by the country in which the work is performed and were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
United States$1,285 $1,300 $2,585 $403 $1,120 $1,523 
International55851906 68 460 528 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
United States$2,507 $2,563 $5,070 $787 $2,183 $2,970 
International1191,718 1,837 143 921 1,064 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Changes in Estimates on Contracts
Changes in estimated contract earnings at completion using the cumulative catch-up method of accounting were recognized in revenues as follows:
Three Months EndedSix Months Ended
(Amounts in millions)
March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Favorable earnings at completion adjustments$48 $28 $68 $23 
Unfavorable earnings at completion adjustments(27)(9)(40)(7)
Net favorable adjustments$21 $19 $28 $16 
Impact on diluted earnings per share attributable to common shareholders (1)
$0.07 $0.17 $0.09 $0.14 
(1)    The impact on diluted loss per share attributable to common shareholders is calculated using our statutory rate.
Remaining Performance Obligations
As of March 28, 2025, we had a remaining performance obligations balance of $10.7 billion and expect to recognize approximately 72% and 87% of the remaining performance obligations balance as revenues over the next 12 and 24 months, respectively, with the remainder to be recognized thereafter.
Contract Balances
The Company's contract balances consisted of the following (in millions):
As of
Description of Contract Related BalanceClassificationMarch 28, 2025September 27, 2024
Billed and billable receivablesAccounts receivable, net$1,556 $1,378 
Contract assetsAccounts receivable, net910 986 
Related party receivablesAccounts receivable, net43 37 
Long-term contract assetsOther long-term assets138 138 
Contract liabilities - deferred revenues and other contract liabilitiesContract liabilities(112)(113)
Contract assets primarily relate to accruals for reimbursable costs and fees in which our right to consideration is conditional. Long-term contract assets relate to a prior acquisition and are discussed further in Note 14 — Legal Proceedings and Commitments and Contingencies.
The Company has related party receivables due from our equity method investments, discussed further in Note 10 — Joint Ventures.
During the three and six months ended March 28, 2025, we recognized revenues of $8 million and $73 million, respectively, compared with $6 million and $82 million of revenues during the three and six months ended March 29, 2024, respectively, that was included in Contract liabilities as of September 27, 2024 and September 29, 2023, respectively.
v3.25.1
Sales of Receivables
 6 Months Ended
Mar. 28, 2025
Transfers and Servicing of Financial Assets [Abstract]  
Sales of Receivables Sales of Receivables
In March 2024, we entered into a Master Accounts Receivable Purchase Agreement (“MARPA”) with MUFG Bank, Ltd., (the “Purchaser”) for the sale of certain designated eligible U.S. Government receivables. On December 30, 2024, the Company amended its MARPA with the Purchaser to increase the maximum amount of eligible receivables that can be sold, including certain billed and unbilled receivables, up to $400 million, an increase of $150 million. Under the MARPA, the Company can sell certain eligible receivables without recourse for any U.S. Government credit risk.
The Company's MARPA activity consisted of the following (in millions):
As of and for the Six Months Ended
March 28, 2025March 29, 2024
Beginning balance:$177 $— 
Sales of receivables1,955 50 
Cash collections(1,912)— 
Outstanding balance sold to Purchaser (1)
220 50 
Cash collected, not remitted to Purchaser (2)
(44)(14)
Remaining sold receivables$176 $36 
(1)    For the six months ended March 28, 2025 and March 29, 2024, the Company recorded a net cash inflow of $43 million and $50 million in its cash flows from operating activities, respectively, from sold receivables. MARPA cash flows are calculated as the change in the outstanding balance during the fiscal year.
(2)    Includes the cash collected on behalf of but not yet remitted to the Purchaser as of March 28, 2025 and March 29, 2024. This balance is included in Other accrued liabilities as of the balance sheet date.
v3.25.1
Goodwill and Intangible Assets
 6 Months Ended
Mar. 28, 2025
Goodwill and Intangible Assets Disclosure [Abstract]  
Goodwill and Intangible Assets Goodwill and Intangible Assets
Goodwill
The table below presents changes in the carrying amount of goodwill by reportable segment for the periods presented:
(Amounts in millions)DSGESTotal
Balance as of September 27, 2024
$2,412 $3,144 $5,556 
Measurement period adjustments (1)
4 98 102 
Balance as of March 28, 2025
$2,416 $3,242 $5,658 
(1)    Represents changes to goodwill resulting from measurement period adjustments recorded in fiscal year 2025 associated with the acquisition of CMS purchase price allocation.
During the first quarter of fiscal year 2025, we amended our organization structure. We performed an interim goodwill impairment test both before and after the business realignment and did not record an impairment charge as a result of the tests.
Intangible Assets
Intangible assets, net consisted of the following:
March 28, 2025September 27, 2024
(Amounts in millions)Gross
Carrying
Value		Accumulated
Amortization		NetGross
Carrying
Value		Accumulated
Amortization		Net
Backlog$936 $(704)$232 $931 $(552)$379 
Customer relationship intangible assets2,746 (638)2,108 2,781 (550)2,231 
Capitalized software24 (11)13 23 (10)13 
Total intangible assets, net$3,706 $(1,353)$2,353 $3,735 $(1,112)$2,623 

Amortization expense was $120 million and $240 million for the three and six months ended March 28, 2025, respectively, and $58 million and $114 million for the three and six months ended March 29, 2024, respectively.
v3.25.1
Income Taxes
 6 Months Ended
Mar. 28, 2025
Income Tax Disclosure [Abstract]  
Income Taxes Income Taxes
The Company's effective tax rate was 91.7% and 66.7% for the three and six months ended March 28, 2025, respectively, and (90.9)% and (72.3)% for the three and six months ended March 29, 2024, respectively.
The most significant item contributing to the difference between the statutory U.S. federal corporate tax rate of 21.0% and the Company’s effective tax rate for the three and six months ended March 28, 2025 and March 29, 2024 was an increase in the valuation allowance against the deferred tax asset related to disallowed interest expense of $17 million and $28 million, respectively, for the three and six months ended March 28, 2025, and $21 million and $44 million, respectively, for the three and six months ended March 29, 2024.
v3.25.1
Debt
 6 Months Ended
Mar. 28, 2025
Debt Disclosure [Abstract]  
Debt Debt
Debt consisted of the following:
As of
(Amounts in millions)March 28, 2025September 27, 2024
Term Loan$3,750 $3,750 
Senior notes1,000 1,000 
Other12 17 
Total debt4,762 4,767 
Unamortized original issue discount and unamortized deferred financing costs(83)(88)
Total debt, net of original issue discount and deferred financing costs4,679 4,679 
Less current portion of long-term debt(43)(36)
Total long-term debt, net of current portion$4,636 $4,643 
As amended, the Company’s senior secured credit facility (the “Credit Facility”) consists of a seven year, $3,750 million term facility (“Term Loan”) and a five year, $850 million revolving facility (“Revolver”), including a $200 million letter of credit subfacility and a $100 million swingline subfacility.
The interest rates applicable to the Term Loan are floating interest rates equal to an Alternate Base Rate or Adjusted Term Secured Overnight Financing Rate plus an applicable margin based upon net leverage ratio. The Term Loan matures on September 27, 2031 and requires quarterly principal amortization payments of $9 million commencing March 31, 2025 with the remainder of the principal thereunder being due at maturity. The Revolver matures on September 27, 2029.
As of March 28, 2025 and September 27, 2024, the available borrowing capacity under the Credit Facility was $775 million and $808 million, respectively, and included $75 million and $42 million, respectively, in issued letters of credit. As of March 28, 2025 and September 27, 2024, there were no amounts borrowed under the Revolver.
In August 2024, the Company completed an offering of $1,000 million in aggregate principal amount of 7.250% senior notes due August 1, 2032 (the “Senior Notes”). Interest is payable on February 1 and August 1 of each year, which commenced on February 1, 2025.
The Credit Facility and the Senior Notes are guaranteed by substantially all of our wholly owned material domestic restricted subsidiaries, subject to customary exceptions set forth in the credit agreement and indenture, respectively.
Each of the credit agreement and indenture requires us to comply with certain representations and warranties, customary affirmative and negative covenants and, in the case of the Revolver, under certain circumstances, a financial covenant. We were in compliance with all covenants as of March 28, 2025.
Cash Flow Hedges
The Company utilizes derivative financial instruments to manage interest rate risk related to its variable rate debt. The Company’s objective is to manage its exposure to interest rate movements and reduce volatility of interest expense. The Company entered into several interest rate swaps with an aggregate notional value of $1.9 billion that were designated as cash flow hedges, in which the Company will pay at the fixed rate and receive payment at a floating rate indexed to the three-month term SOFR through maturity. The swaps mature at various dates through January 31, 2027. The change in fair value of the interest rate swaps is presented within accumulated other comprehensive income on our consolidated balance sheet and subsequently reclassified into interest expense and other, net on our consolidated statements of income and comprehensive loss in the period when the hedged transaction affects earnings.
v3.25.1
Joint Ventures
 6 Months Ended
Mar. 28, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Joint Ventures Joint Ventures
The Company’s joint ventures provide services to customers including program management and operations and maintenance services. Joint ventures, the combination of two or more partners, are generally formed for a specific project. Management of the joint venture is typically controlled by a joint venture executive committee, comprised of representatives from the joint venture partners. The joint venture executive committee normally provides management oversight and controls decisions which could have a significant impact on the joint venture.
We account for joint ventures in accordance with ASC 810, Consolidation. The Company analyzes its joint ventures and classifies them as either:
•a Variable Interest Entity (“VIE”) that must be consolidated because the Company is the primary beneficiary or the joint venture is not a VIE and the Company holds the majority voting interest with no significant participative rights available to the other partners; or
•a VIE that does not require consolidation and is treated as an equity method investment because the Company is not the primary beneficiary or the joint venture is not a VIE and the Company does not hold the majority voting interest.
The following table presents selected financial information for our consolidated joint ventures that are VIEs as of March 28, 2025 and September 27, 2024:
As of
(Amounts in millions)March 28, 2025September 27, 2024
Cash and cash equivalents$143 $160 
Current assets325 322 
Non-current assets3 2 
Total assets$471 $484 
Current liabilities$169 $190 
Non-current liabilities1 1 
Total liabilities170 191 
Total Amentum equity231 228 
Non-controlling interests70 65 
Total equity301 293 
Total liabilities and equity$471 $484 
The following table presents selected financial information for our consolidated joint ventures that are VIEs for the three and six months ended March 28, 2025 and March 29, 2024:
Three Months EndedSix Months Ended
(Amounts in millions)March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Revenues$367 $67 $743 $136 
Cost of revenues(331)(57)(667)(115)
Net income including non-controlling interests36 10 75 20 

The Company has an ownership share in more than 20 active joint ventures that are accounted for as equity method investments and the Company’s ownership percentages generally range from 10% to 51%. Related party receivables due from our equity method investments were $43 million and $37 million as of March 28, 2025 and September 27, 2024, respectively. These receivables are a result of items purchased and services rendered by us on behalf of our equity method investments. We have assessed these receivables as having minimal collection risk based on our historic experience with these joint ventures and our inherent influence through our ownership interest. The related party revenues earned from our equity method investments was $45 million and $89 million for the three and six months ended March 28, 2025, respectively, and $17 million and $33 million for the three and six months ended March 29, 2024, respectively.
Many of our joint ventures only perform on a single contract. The modification or termination of a contract under a joint venture could trigger an impairment in the fair value of our investment in these entities. In the aggregate, our maximum exposure to losses was $193 million related to our equity method investments as of March 28, 2025.
v3.25.1
Accumulated Other Comprehensive Income (Loss)
 6 Months Ended
Mar. 28, 2025
Equity [Abstract]  
Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss)
The accumulated balances and reporting period activities for the three and six months ended March 28, 2025 and March 29, 2024 related to accumulated other comprehensive income (loss) are summarized as follows:
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at December 27, 2024$— $(15)$55 $(17)$23 
Other comprehensive (loss) income before reclassification(6)11 — 2 7 
Amounts reclassified from accumulated other comprehensive (loss) income(1)— — — (1)
Balance at March 28, 2025$(7)$(4)$55 $(15)$29 
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at December 29, 2023$(4)$1 $46 $(14)$29 
Other comprehensive (loss) income before reclassification18 (2)— (3)13 
Amounts reclassified from accumulated other comprehensive (loss) income(3)— (1)1 (3)
Balance at March 29, 2024$11 $(1)$45 $(16)$39 
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at September 27, 2024$(22)$3 $55 $(13)$23 
Other comprehensive (loss) income before reclassification19 (7)— (2)10 
Amounts reclassified from accumulated other comprehensive (loss) income(4)— — — (4)
Balance at March 28, 2025$(7)$(4)$55 $(15)$29 
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at September 29, 2023$25 $(5)$46 $(18)$48 
Other comprehensive (loss) income before reclassification(9)4 — 1 (4)
Amounts reclassified from accumulated other comprehensive income (loss)(5)— (1)1 (5)
Balance at March 29, 2024$11 $(1)$45 $(16)$39 
v3.25.1
Segment Information
 6 Months Ended
Mar. 28, 2025
Segment Reporting [Abstract]  
Segment Information Segment Information
In the first quarter of fiscal year 2025, we amended our organizational structure, which resulted in the identification of two reportable segments: Digital Solutions (“DS”) and Global Engineering Solutions (“GES”).
The DS segment provides advanced digital and data-driven solutions including intelligence analytics, space system development, cybersecurity, and next generation IT across the federal government and commercial clients.
The GES segment provides large-scale environmental remediation, clean energy, platform engineering, sustainment and supply chain management across all seven continents for the U.S. government and allied nations.
The presentation of financial results as two reportable segments is consistent with the way the Company operates its business and the manner in which our chief operating decision maker (“CODM”), currently our Chief Executive Officer, manages the operations of the Company for purposes of allocating resources and assessing performance. The CODM evaluates the performance of our segments based on revenues and Adjusted EBITDA. Prior year performance measures have been recast to reflect the current reportable segment structure.
The Company’s segment revenues were as follows:
Three Months EndedSix Months Ended
(Amounts in millions)March 28, 2025March 29, 2024March 28, 2025March 29, 2024
DS$1,340 $471 $2,626 $930 
GES2,151 1,580 4,281 3,104 
Total$3,491 $2,051 $6,907 $4,034 
Adjusted EBITDA is most comparable to net income (loss) attributable to common shareholders prepared based on GAAP. The Company defines Adjusted EBITDA as net income (loss) attributable to common shareholders adjusted for interest expense and other, net, provision for income taxes, depreciation and amortization, and certain discrete items that are not considered in the evaluation of ongoing operating performance. These discrete items include acquisition, transaction, and integration costs, non-cash gains and losses, loss on extinguishment of debt, utilization of certain fair market value adjustments assigned in purchase accounting, and share-based compensation. While we believe Adjusted EBITDA is a useful metric in evaluating operating performance by allowing better evaluation of underlying segment performance and better period-to-period comparability, it is not a metric defined by GAAP and may not be comparable to non-GAAP metrics presented by other companies.
The following table reconciles segment Adjusted EBITDA to net income (loss) attributable to common shareholders:
Three months endedSix months ended
(Amounts in millions)March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Adjusted EBITDA by segment
DS$107 $40 $207 $78 
GES161 116 323 232 
Adjusted EBITDA attributable to Amentum Holdings, Inc.268 156 530 310 
Depreciation expense(9)(5)(18)(12)
Amortization of intangibles(120)(58)(240)(114)
Interest expense and other, net(86)(111)(173)(222)
Non-controlling interests(2)(1)7 1 
Acquisition, transaction and integration costs1
(21)(4)(30)(11)
Utilization of fair market value adjustments2
(1)2 1 3 
Share-based compensation3
(5)(1)(8)(2)
Income (loss) before income taxes24 (22)69 (47)
Provision for income taxes(22)(20)(46)(34)
Net income (loss) including non-controlling interests2 (42)23 (81)
Net income (loss) attributable to non-controlling interests2 1 (7)(1)
Net income (loss) attributable to common shareholders$4 $(41)$16 $(82)
(1)    Represents acquisition, transaction and integration costs, including severance, retention, and other adjustments related to acquisition and integration activities.
(2)    Represents the periodic utilization of the fair market value adjustments assigned to certain equity method investments and non-controlling interests based on the remaining period of performance for the related contract.
(3)    Represents non-cash compensation expenses recognized for share based arrangements.
Asset information by segment is not a key measure of performance used by the CODM.
v3.25.1
Earnings (Loss) Per Share
 6 Months Ended
Mar. 28, 2025
Earnings Per Share [Abstract]  
Earnings (Loss) Per Share Earnings (Loss) Per Share
For the three and six months ended March 29, 2024, the Company retrospectively adjusted the weighted average shares used in determining loss per share to reflect the conversion of the ownership interests of Amentum Parent Holdings LLC held by AJVLP that converted into 90,021,804 shares of the Company’s common stock at Transaction close. There were no anti-dilutive shares for the three and six months ended March 29, 2024.
Basic and diluted earnings (loss) per share are computed as follows (in millions, except per share data):
Three Months EndedSix Months Ended
March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Net income (loss) attributable to common shareholders$4 $(41)$16 $(82)
Weighted-average number of basic shares outstanding during the period2439024390
Weighted-average number of diluted shares outstanding during the period2439024390
Basic earnings (loss) per share$0.02 $(0.46)$0.07 $(0.91)
Diluted earnings (loss) per share$0.02 $(0.46)$0.07 $(0.91)
v3.25.1
Legal Proceedings and Commitments and Contingencies
 6 Months Ended
Mar. 28, 2025
Commitments and Contingencies Disclosure [Abstract]  
Legal Proceedings and Commitments and Contingencies Legal Proceedings and Commitments and Contingencies
The Company is involved in various claims, disputes and administrative proceedings arising in the normal course of business. Liabilities for loss contingencies arising from claims, assessments, litigation, fines and penalties and other sources are recorded when it is probable that an unfavorable result and/or liability will be incurred and the cost of the unfavorable result or liability can be reasonably estimated. Management is of the opinion that any liability or loss associated with such matters, either individually or in the aggregate, will not have a material adverse effect on the Company’s operations and liquidity.
Payments to the Company on cost-plus-fee contracts are provisional and are subject to adjustments upon audit by the Defense Contract Audit Agency (“DCAA”). In management’s opinion, audit adjustments that may result from audits not yet completed or started are not expected to have a material adverse effect on the Company’s operations and liquidity.
Pending Litigation and Claims
Department of Energy Claims
In January 2020, the Company purchased assets and assumed liabilities associated with AECOM Energy & Construction, Inc. (the “Acquired Affiliate”) from AECOM (the “Seller”). At the time of the acquisition, the Acquired Affiliate had pending claims against the U.S. Department of Energy (“DOE”) related to a contract performed prior to the acquisition. The Company and the Seller agreed that all future claim recoveries and costs with the DOE would be split 10% to the Company and 90% to the Seller. Following the DOE’s denial of the claims, on December 20, 2020, the Acquired Affiliate filed an appeal of these decisions in the U.S. Court of Federal Claims. The Company has estimated and recorded $138 million within other long-term assets on the balance sheet and $125 million within other long-term liabilities on the balance sheet representing the Company’s payable to the Seller related to this matter. No changes to these amounts have been recorded since the acquisition. The Company intends to cooperate with the Seller in the pursuit of all claimed amounts but can provide no certainty that the Company will recover the claims. The Company does not believe any additional incurred claims or costs related to this matter will have a material adverse effect on the Company’s results of operations.
U.S. Government Investigations
We primarily sell our services to the U.S. Government. These contracts are subject to extensive legal and regulatory requirements, and we are occasionally the subject of investigations by various agencies of the U.S. Government who investigate whether our operations are being conducted in accordance with these requirements. Such investigations could result in administrative, civil or criminal liabilities, including repayments, fines or penalties being imposed on us, or could lead to suspension or debarment from future U.S. Government contracting. U.S. Government investigations often take years to complete and may result in adverse action against us. Any adverse actions arising from such matters could have a material effect on our ability to invoice and receive timely payment on our contracts, perform contracts or compete for contracts with the U.S. Government and could have a material effect on our operating performance. There are currently no investigations that are expected to have a material impact on our results of operations.
v3.25.1
Subsequent Event
 6 Months Ended
Mar. 28, 2025
Subsequent Events [Abstract]  
Subsequent Events Subsequent Event
Divestiture of Rapid Solutions
On April 23, 2025, we entered into a definitive agreement to sell our hardware and product business, Rapid Solutions, to Lockheed Martin for a purchase price of $360 million in cash, subject to regulatory approvals and customary closing conditions. The planned sale of the Rapid Solutions business is not classified as discontinued operations as it does not represent a strategic shift in our business.
v3.25.1
Pay vs Performance Disclosure - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Pay vs Performance Disclosure        
Net income (loss) attributable to common shareholders $ 4 $ (41) $ 16 $ (82)
v3.25.1
Insider Trading Arrangements
 3 Months Ended
Mar. 28, 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
v3.25.1
Basis of Presentation (Policies)
 6 Months Ended
Mar. 28, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Segments
During the first quarter of fiscal year 2025, we announced the realignment of our reporting structure, which resulted in the identification of two reportable segments: Digital Solutions (“DS”) and Global Engineering Solutions (“GES”). The DS segment provides advanced digital and data-driven solutions including intelligence analytics, space system development, cybersecurity, and next generation IT across the federal government and commercial clients. The GES segment provides large-scale environmental remediation, clean energy, platform engineering, sustainment and supply chain management across all seven continents for the U.S. government and allied nations. As a result of this change, prior year segment disclosures have been recast to reflect the current reportable segment structure.
Basis of Presentation Certain information and note disclosures normally included in the annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted, although the Company believes that the disclosures made are adequate to make the information presented not misleading.
Consolidation All intercompany transactions and balances have been eliminated in consolidation.
Accounting Standards Updates Issued but Not Yet Adopted
Accounting Standards Updates Issued but Not Yet Adopted

In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, to improve reportable segment disclosure requirements. This update requires disclosure of significant segment expenses and other segment items in annual and interim periods. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. The amendment requires retrospective application to all prior periods presented in the financial statements, and early adoption is permitted. We are currently evaluating the impacts of the new standard on our consolidated financial statements.
In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, to enhance transparency and usefulness of income tax disclosures. This update requires disaggregated information about an entity’s effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, and may be applied on a prospective or retrospective basis. Early adoption is permitted. We are currently evaluating the impacts of the new standard on our financial statement disclosures.
Joint Ventures
The Company’s joint ventures provide services to customers including program management and operations and maintenance services. Joint ventures, the combination of two or more partners, are generally formed for a specific project. Management of the joint venture is typically controlled by a joint venture executive committee, comprised of representatives from the joint venture partners. The joint venture executive committee normally provides management oversight and controls decisions which could have a significant impact on the joint venture.
We account for joint ventures in accordance with ASC 810, Consolidation. The Company analyzes its joint ventures and classifies them as either:
•a Variable Interest Entity (“VIE”) that must be consolidated because the Company is the primary beneficiary or the joint venture is not a VIE and the Company holds the majority voting interest with no significant participative rights available to the other partners; or
•a VIE that does not require consolidation and is treated as an equity method investment because the Company is not the primary beneficiary or the joint venture is not a VIE and the Company does not hold the majority voting interest.
v3.25.1
Acquisitions (Tables)
 6 Months Ended
Mar. 28, 2025
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]  
Schedule of Preliminary Allocation of the Purchase Price
Under the acquisition method of accounting, total consideration exchanged for the CMS transaction is shown below and increased $7 million from September 27, 2024:
(In millions, except per share amounts)
Shares of Amentum Holdings, Inc. common stock issued to CMS shareholders142 
Per share price of Amentum Holdings, Inc. common stock25.67 
Fair value of common stock issued to CMS shareholders (1)
3,654 
Fair value of additional equity consideration issued to CMS shareholders (2)
218 
Final working capital settlement (3)
70 
Other consideration (4)
6 
Fair value of consideration transferred3,948 
Fair value of previously held equity interest (5)
84 
Total consideration$4,032 
(1)    Represents the fair value of equity consideration received by CMS Shareholders to provide 58.5% ownership in the Company.
(2)    Represents the Additional Equity Consideration which was finalized in March 2025. The balance reflects a decrease in equity consideration issued to CMS Shareholders following a resolution to release an additional 1.0% of the issued and outstanding shares of Amentum common stock back to Sponsor Stockholder. This balance is presented at fair value based on the acquisition-date share price and is included in the total purchase consideration in accordance with ASC 805.
(3)    Reflects a $70 million cash payment made based on the final net working capital position. This payment was made in the third quarter of fiscal year 2025 and is included in the total purchase consideration in accordance with ASC 805, as it represents an obligation attributable to pre-acquisition activities.
(4)    Represents other immaterial adjustments, including a) estimated equity consideration related to pre-combination share-based compensation awards, b) the settlement of CMS transaction costs paid by Amentum, and c) the removal of consideration related to the acquisition of non-controlling interests.
    
(5)    Prior to the Transaction, we held a non-controlling interest in a joint venture of 50% which was accounted for under the equity method of accounting, with the remaining 40% held by the CMS Business and 10% held by an unrelated third party. As a result of the Transaction, the Company gained a controlling financial interest in the joint venture and it became a consolidated joint venture of the Company. This joint venture acquisition was accounted for as a business combination achieved in stages. Our pre-existing equity method investment in the joint venture was remeasured at an acquisition date fair value of $170 million by using a discounted cash flow model based on estimated future revenues, margins and discount rates, among other variables and estimates. Additionally, as of the acquisition date, the Company had a payable to the joint venture with a fair value of $1 million that was settled in connection with the acquisition.
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed
The preliminary allocation of the purchase price is as follows:
(Amounts in millions)
Preliminary Allocation of Purchase PriceMeasurement Period Adjustments, NetPreliminary Adjusted Allocation of Purchase Price
Cash and cash equivalents$488 $— $488 
Accounts receivable1,043 (21)1,022 
Prepaid expenses and other current assets82 (5)77 
Property and equipment72 (2)70 
Equity method investments17 50 67 
Goodwill2,665 102 2,767 
Intangible assets1,860 (30)1,830 
Other long-term assets107 16 123 
Current portion of long-term debt(8)— (8)
Accounts payable(257)— (257)
Accrued compensation and benefits(285)— (285)
Contract liabilities(48)3 (45)
Other current liabilities(98)(42)(140)
Long-term debt, net of current portion(1,122)— (1,122)
Deferred tax liabilities(353)27 (326)
Other long-term liabilities(75)(16)(91)
Non-controlling interests(63)(75)(138)
Total consideration$4,025 $7 $4,032 
v3.25.1
Revenues (Tables)
 6 Months Ended
Mar. 28, 2025
Revenue from Contract with Customer [Abstract]  
Schedule of Disaggregation of Revenue
Disaggregated revenues by customer-type were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Department of Defense and U.S. Intelligence Community$738 $1,070 $1,808 $354 $1,030 $1,384 
Other U.S. Government Agencies40558599095398493 
Commercial and International197496693 22152174
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Department of Defense and U.S. Intelligence Community$1,460 $2,116 $3,576 $705 $1,982 $2,687 
Other U.S. Government Agencies8211,185 2,006 182771953 
Commercial and International3459801,325 43351394
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Disaggregated revenues by contract-type were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Cost-plus-fee$861 $1,388 $2,249 $216 $1,052 $1,268 
Fixed-price331476807161388549 
Time-and-materials148287435 94140234 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Cost-plus-fee$1,646 $2,769 $4,415 $435 $2,087 $2,522 
Fixed-price6909481,638 3167421,058 
Time-and-materials290564854 179275454 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Disaggregated revenues by prime contractor versus subcontractor were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Prime contractor$1,215 $1,885 $3,100 $417 $1,410 $1,827 
Subcontractor125 266 391 54170224 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
Prime contractor$2,379 $3,763 $6,142 $826 $2,761 $3,587 
Subcontractor247518765 104343447 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 

Revenues by geographic location are reported by the country in which the work is performed and were as follows:
Three Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
United States$1,285 $1,300 $2,585 $403 $1,120 $1,523 
International55851906 68 460 528 
Total revenues$1,340 $2,151 $3,491 $471 $1,580 $2,051 
Six Months Ended
March 28, 2025March 29, 2024
(Amounts in millions)DSGESTotalDSGESTotal
United States$2,507 $2,563 $5,070 $787 $2,183 $2,970 
International1191,718 1,837 143 921 1,064 
Total revenues$2,626 $4,281 $6,907 $930 $3,104 $4,034 
Schedule of Changes in Estimated Contract Earnings
Changes in estimated contract earnings at completion using the cumulative catch-up method of accounting were recognized in revenues as follows:
Three Months EndedSix Months Ended
(Amounts in millions)
March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Favorable earnings at completion adjustments$48 $28 $68 $23 
Unfavorable earnings at completion adjustments(27)(9)(40)(7)
Net favorable adjustments$21 $19 $28 $16 
Impact on diluted earnings per share attributable to common shareholders (1)
$0.07 $0.17 $0.09 $0.14 
(1)    The impact on diluted loss per share attributable to common shareholders is calculated using our statutory rate.
The Company's contract balances consisted of the following (in millions):
As of
Description of Contract Related BalanceClassificationMarch 28, 2025September 27, 2024
Billed and billable receivablesAccounts receivable, net$1,556 $1,378 
Contract assetsAccounts receivable, net910 986 
Related party receivablesAccounts receivable, net43 37 
Long-term contract assetsOther long-term assets138 138 
Contract liabilities - deferred revenues and other contract liabilitiesContract liabilities(112)(113)
v3.25.1
Contract Balances (Tables)
 6 Months Ended
Mar. 28, 2025
Revenue from Contract with Customer [Abstract]  
Schedule of Contract Balances
Changes in estimated contract earnings at completion using the cumulative catch-up method of accounting were recognized in revenues as follows:
Three Months EndedSix Months Ended
(Amounts in millions)
March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Favorable earnings at completion adjustments$48 $28 $68 $23 
Unfavorable earnings at completion adjustments(27)(9)(40)(7)
Net favorable adjustments$21 $19 $28 $16 
Impact on diluted earnings per share attributable to common shareholders (1)
$0.07 $0.17 $0.09 $0.14 
(1)    The impact on diluted loss per share attributable to common shareholders is calculated using our statutory rate.
The Company's contract balances consisted of the following (in millions):
As of
Description of Contract Related BalanceClassificationMarch 28, 2025September 27, 2024
Billed and billable receivablesAccounts receivable, net$1,556 $1,378 
Contract assetsAccounts receivable, net910 986 
Related party receivablesAccounts receivable, net43 37 
Long-term contract assetsOther long-term assets138 138 
Contract liabilities - deferred revenues and other contract liabilitiesContract liabilities(112)(113)
v3.25.1
Sales of Receivables (Tables)
 6 Months Ended
Mar. 28, 2025
Transfers and Servicing of Financial Assets [Abstract]  
Schedule of MARPA Activity
The Company's MARPA activity consisted of the following (in millions):
As of and for the Six Months Ended
March 28, 2025March 29, 2024
Beginning balance:$177 $— 
Sales of receivables1,955 50 
Cash collections(1,912)— 
Outstanding balance sold to Purchaser (1)
220 50 
Cash collected, not remitted to Purchaser (2)
(44)(14)
Remaining sold receivables$176 $36 
(1)    For the six months ended March 28, 2025 and March 29, 2024, the Company recorded a net cash inflow of $43 million and $50 million in its cash flows from operating activities, respectively, from sold receivables. MARPA cash flows are calculated as the change in the outstanding balance during the fiscal year.
(2)    Includes the cash collected on behalf of but not yet remitted to the Purchaser as of March 28, 2025 and March 29, 2024. This balance is included in Other accrued liabilities as of the balance sheet date.
v3.25.1
Goodwill and Intangible Assets (Tables)
 6 Months Ended
Mar. 28, 2025
Goodwill and Intangible Assets Disclosure [Abstract]  
Schedule of Changes in the Carrying Amount of Goodwill
The table below presents changes in the carrying amount of goodwill by reportable segment for the periods presented:
(Amounts in millions)DSGESTotal
Balance as of September 27, 2024
$2,412 $3,144 $5,556 
Measurement period adjustments (1)
4 98 102 
Balance as of March 28, 2025
$2,416 $3,242 $5,658 
(1)    Represents changes to goodwill resulting from measurement period adjustments recorded in fiscal year 2025 associated with the acquisition of CMS purchase price allocation.
Schedule of Intangible Assets, Net
Intangible assets, net consisted of the following:
March 28, 2025September 27, 2024
(Amounts in millions)Gross
Carrying
Value		Accumulated
Amortization		NetGross
Carrying
Value		Accumulated
Amortization		Net
Backlog$936 $(704)$232 $931 $(552)$379 
Customer relationship intangible assets2,746 (638)2,108 2,781 (550)2,231 
Capitalized software24 (11)13 23 (10)13 
Total intangible assets, net$3,706 $(1,353)$2,353 $3,735 $(1,112)$2,623 
v3.25.1
Debt (Tables)
 6 Months Ended
Mar. 28, 2025
Debt Disclosure [Abstract]  
Schedule of Debt
Debt consisted of the following:
As of
(Amounts in millions)March 28, 2025September 27, 2024
Term Loan$3,750 $3,750 
Senior notes1,000 1,000 
Other12 17 
Total debt4,762 4,767 
Unamortized original issue discount and unamortized deferred financing costs(83)(88)
Total debt, net of original issue discount and deferred financing costs4,679 4,679 
Less current portion of long-term debt(43)(36)
Total long-term debt, net of current portion$4,636 $4,643 
v3.25.1
Joint Ventures (Tables)
 6 Months Ended
Mar. 28, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Selected Financial Information for our Consolidated Joint Ventures VIEs
The following table presents selected financial information for our consolidated joint ventures that are VIEs as of March 28, 2025 and September 27, 2024:
As of
(Amounts in millions)March 28, 2025September 27, 2024
Cash and cash equivalents$143 $160 
Current assets325 322 
Non-current assets3 2 
Total assets$471 $484 
Current liabilities$169 $190 
Non-current liabilities1 1 
Total liabilities170 191 
Total Amentum equity231 228 
Non-controlling interests70 65 
Total equity301 293 
Total liabilities and equity$471 $484 
The following table presents selected financial information for our consolidated joint ventures that are VIEs for the three and six months ended March 28, 2025 and March 29, 2024:
Three Months EndedSix Months Ended
(Amounts in millions)March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Revenues$367 $67 $743 $136 
Cost of revenues(331)(57)(667)(115)
Net income including non-controlling interests36 10 75 20 
v3.25.1
Accumulated Other Comprehensive Income (Loss) (Tables)
 6 Months Ended
Mar. 28, 2025
Equity [Abstract]  
Schedule of Accumulated Other Comprehensive Income (Loss)
The accumulated balances and reporting period activities for the three and six months ended March 28, 2025 and March 29, 2024 related to accumulated other comprehensive income (loss) are summarized as follows:
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at December 27, 2024$— $(15)$55 $(17)$23 
Other comprehensive (loss) income before reclassification(6)11 — 2 7 
Amounts reclassified from accumulated other comprehensive (loss) income(1)— — — (1)
Balance at March 28, 2025$(7)$(4)$55 $(15)$29 
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at December 29, 2023$(4)$1 $46 $(14)$29 
Other comprehensive (loss) income before reclassification18 (2)— (3)13 
Amounts reclassified from accumulated other comprehensive (loss) income(3)— (1)1 (3)
Balance at March 29, 2024$11 $(1)$45 $(16)$39 
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at September 27, 2024$(22)$3 $55 $(13)$23 
Other comprehensive (loss) income before reclassification19 (7)— (2)10 
Amounts reclassified from accumulated other comprehensive (loss) income(4)— — — (4)
Balance at March 28, 2025$(7)$(4)$55 $(15)$29 
Gain (Loss) on Derivative InstrumentsForeign Currency Translation AdjustmentsPension Related AdjustmentsIncome Tax (Provision) Benefit Related to Items of Other Comprehensive Income (Loss)Accumulated Other Comprehensive Income (Loss)
(Amounts in millions)
Balance at September 29, 2023$25 $(5)$46 $(18)$48 
Other comprehensive (loss) income before reclassification(9)4 — 1 (4)
Amounts reclassified from accumulated other comprehensive income (loss)(5)— (1)1 (5)
Balance at March 29, 2024$11 $(1)$45 $(16)$39 
v3.25.1
Segment Information (Tables)
 6 Months Ended
Mar. 28, 2025
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information
The Company’s segment revenues were as follows:
Three Months EndedSix Months Ended
(Amounts in millions)March 28, 2025March 29, 2024March 28, 2025March 29, 2024
DS$1,340 $471 $2,626 $930 
GES2,151 1,580 4,281 3,104 
Total$3,491 $2,051 $6,907 $4,034 
The following table reconciles segment Adjusted EBITDA to net income (loss) attributable to common shareholders:
Three months endedSix months ended
(Amounts in millions)March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Adjusted EBITDA by segment
DS$107 $40 $207 $78 
GES161 116 323 232 
Adjusted EBITDA attributable to Amentum Holdings, Inc.268 156 530 310 
Depreciation expense(9)(5)(18)(12)
Amortization of intangibles(120)(58)(240)(114)
Interest expense and other, net(86)(111)(173)(222)
Non-controlling interests(2)(1)7 1 
Acquisition, transaction and integration costs1
(21)(4)(30)(11)
Utilization of fair market value adjustments2
(1)2 1 3 
Share-based compensation3
(5)(1)(8)(2)
Income (loss) before income taxes24 (22)69 (47)
Provision for income taxes(22)(20)(46)(34)
Net income (loss) including non-controlling interests2 (42)23 (81)
Net income (loss) attributable to non-controlling interests2 1 (7)(1)
Net income (loss) attributable to common shareholders$4 $(41)$16 $(82)
(1)    Represents acquisition, transaction and integration costs, including severance, retention, and other adjustments related to acquisition and integration activities.
(2)    Represents the periodic utilization of the fair market value adjustments assigned to certain equity method investments and non-controlling interests based on the remaining period of performance for the related contract.
(3)    Represents non-cash compensation expenses recognized for share based arrangements.
v3.25.1
Earnings (Loss) Per Share (Tables)
 6 Months Ended
Mar. 28, 2025
Earnings Per Share [Abstract]  
Schedule of Earnings (Loss) Per Share
Basic and diluted earnings (loss) per share are computed as follows (in millions, except per share data):
Three Months EndedSix Months Ended
March 28, 2025March 29, 2024March 28, 2025March 29, 2024
Net income (loss) attributable to common shareholders$4 $(41)$16 $(82)
Weighted-average number of basic shares outstanding during the period2439024390
Weighted-average number of diluted shares outstanding during the period2439024390
Basic earnings (loss) per share$0.02 $(0.46)$0.07 $(0.91)
Diluted earnings (loss) per share$0.02 $(0.46)$0.07 $(0.91)
v3.25.1
Basis of Presentation (Details) - segment
 3 Months Ended 6 Months Ended
Dec. 27, 2024
Mar. 28, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Number of reportable segments 2 2
v3.25.1
Acquisitions - Narrative (Details) - USD ($)
$ in Millions
Sep. 27, 2024
Sep. 26, 2024
Mar. 28, 2025
Business Acquisition [Line Items]      
Common stock, issued (in shares) 243,302,173   243,322,468
Common stock, outstanding (in shares) 243,302,173   243,322,468
CMS      
Business Acquisition [Line Items]      
Percentage of issued and outstanding shares held in escrow 4.50%    
Intangible assets $ 1,860   $ 1,830
CMS | Backlog      
Business Acquisition [Line Items]      
Intangible assets $ 275    
Intangible assets, useful life 1 year    
CMS | Customer relationship intangible assets      
Business Acquisition [Line Items]      
Intangible assets $ 1,555    
Intangible assets, useful life 14 years    
Jacobs Solutions Inc. And Shareholders      
Business Acquisition [Line Items]      
Percentage of issued and outstanding shares of common stock held 58.50%    
Amentum Equityholder      
Business Acquisition [Line Items]      
Percentage of issued and outstanding shares of common stock held 37.00%    
Critical Mission Solutions, Shareholders      
Business Acquisition [Line Items]      
Percentage of issued and outstanding shares of common stock held 3.50%    
Sponsor Stockholder      
Business Acquisition [Line Items]      
Percentage of issued and outstanding shares of common stock held 1.00%    
Jacobs Solutions Inc. | CMS      
Business Acquisition [Line Items]      
Payments of dividends   $ 911  
v3.25.1
Acquisitions - Schedule of Total Consideration Exchange (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 6 Months Ended
Sep. 27, 2024
Mar. 28, 2025
Mar. 29, 2024
Business Acquisition [Line Items]      
Per share price of Amentum Holdings, Inc. common stock (in dollars per share) $ 25.67    
Final working capital settlement   $ 70 $ 0
Equity method investments $ 123 193  
Joint Venture Prior To Acquisition      
Business Acquisition [Line Items]      
Equity method investments $ 170    
Jacobs Solutions Inc. And Shareholders      
Business Acquisition [Line Items]      
Percentage of issued and outstanding shares of common stock held 58.50%    
Critical Mission Solutions, Shareholders      
Business Acquisition [Line Items]      
Percentage of issued and outstanding shares of common stock held 3.50%    
CMS      
Business Acquisition [Line Items]      
Total consideration exchanged   $ 7  
Shares of Amentum Holdings, Inc. common stock issued to CMS shareholders (in shares) 142    
Fair value of common stock issued to CMS shareholders $ 3,654    
Fair value of additional equity consideration issued to CMS shareholders 218    
Other consideration 6    
Fair value of consideration transferred 3,948    
Fair value of previously held equity interest 84    
Total consideration $ 4,032    
Noncontrolling interest ownership percentage 50.00%    
Receivable balance settled in acquisition $ 1    
CMS | Third Party      
Business Acquisition [Line Items]      
Noncontrolling interest ownership percentage 10.00%    
CMS | Critical Mission Solutions, Shareholders      
Business Acquisition [Line Items]      
Noncontrolling interest ownership percentage 40.00%    
v3.25.1
Acquisitions - Schedule of Preliminary Allocation of the Purchase Price (Details) - USD ($)
$ in Millions
 6 Months Ended
Mar. 28, 2025
Sep. 27, 2024
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]    
Goodwill $ 5,658 $ 5,556
Measurement Period Adjustments, Net, Goodwill 102  
CMS    
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]    
Cash and cash equivalents 488 488
Accounts receivable 1,022 1,043
Measurement Period Adjustments, Net, Accounts receivable (21)  
Prepaid expenses and other current assets 77 82
Measurement Period Adjustments, Net, Prepaid expenses and other current assets (5)  
Property and equipment 70 72
Measurement Period Adjustments, Net, Property and Equipment (2)  
Equity method investments 67 17
Measurement Period Adjustments, Net, Equity method investments 50  
Goodwill 2,767 2,665
Measurement Period Adjustments, Net, Goodwill 102  
Intangible assets 1,830 1,860
Measurement Period Adjustments, Net, Intangible assets (30)  
Other long-term assets 123 107
Measurement Period Adjustments, Net, Other long-term assets 16  
Current portion of long-term debt (8) (8)
Accounts payable (257) (257)
Accrued compensation and benefits (285) (285)
Contract liabilities (45) (48)
Measurement Period Adjustments, Net, Contract liabilities 3  
Other current liabilities (140) (98)
Measurement Period Adjustments, Net, Other current liabilities (42)  
Long-term debt, net of current portion (1,122) (1,122)
Deferred tax liabilities (326) (353)
Measurement Period Adjustments, Net, Adjustment, Deferred Tax Liabilities 27  
Other long-term liabilities (91) (75)
Measurement Period Adjustments, Net, Other long-term liabilities (16)  
Non-controlling interests (138) (63)
Measurement Period Adjustments, Net, Non-controlling interests (75)  
Total consideration 4,032 $ 4,025
Total consideration $ 7  
v3.25.1
Revenues - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Disaggregation of Revenue [Line Items]        
Total revenues $ 3,491 $ 2,051 $ 6,907 $ 4,034
United States        
Disaggregation of Revenue [Line Items]        
Total revenues 2,585 1,523 5,070 2,970
International        
Disaggregation of Revenue [Line Items]        
Total revenues 906 528 1,837 1,064
Prime contractor        
Disaggregation of Revenue [Line Items]        
Total revenues 3,100 1,827 6,142 3,587
Subcontractor        
Disaggregation of Revenue [Line Items]        
Total revenues 391 224 765 447
Cost-plus-fee        
Disaggregation of Revenue [Line Items]        
Total revenues 2,249 1,268 4,415 2,522
Fixed-price        
Disaggregation of Revenue [Line Items]        
Total revenues 807 549 1,638 1,058
Time-and-materials        
Disaggregation of Revenue [Line Items]        
Total revenues 435 234 854 454
Department of Defense and U.S. Intelligence Community        
Disaggregation of Revenue [Line Items]        
Total revenues 1,808 1,384 3,576 2,687
Other U.S. Government Agencies        
Disaggregation of Revenue [Line Items]        
Total revenues 990 493 2,006 953
Commercial and International        
Disaggregation of Revenue [Line Items]        
Total revenues 693 174 1,325 394
DS        
Disaggregation of Revenue [Line Items]        
Total revenues 1,340 471 2,626 930
DS | United States        
Disaggregation of Revenue [Line Items]        
Total revenues 1,285 403 2,507 787
DS | International        
Disaggregation of Revenue [Line Items]        
Total revenues 55 68 119 143
DS | Prime contractor        
Disaggregation of Revenue [Line Items]        
Total revenues 1,215 417 2,379 826
DS | Subcontractor        
Disaggregation of Revenue [Line Items]        
Total revenues 125 54 247 104
DS | Cost-plus-fee        
Disaggregation of Revenue [Line Items]        
Total revenues 861 216 1,646 435
DS | Fixed-price        
Disaggregation of Revenue [Line Items]        
Total revenues 331 161 690 316
DS | Time-and-materials        
Disaggregation of Revenue [Line Items]        
Total revenues 148 94 290 179
DS | Department of Defense and U.S. Intelligence Community        
Disaggregation of Revenue [Line Items]        
Total revenues 738 354 1,460 705
DS | Other U.S. Government Agencies        
Disaggregation of Revenue [Line Items]        
Total revenues 405 95 821 182
DS | Commercial and International        
Disaggregation of Revenue [Line Items]        
Total revenues 197 22 345 43
GES        
Disaggregation of Revenue [Line Items]        
Total revenues 2,151 1,580 4,281 3,104
GES | United States        
Disaggregation of Revenue [Line Items]        
Total revenues 1,300 1,120 2,563 2,183
GES | International        
Disaggregation of Revenue [Line Items]        
Total revenues 851 460 1,718 921
GES | Prime contractor        
Disaggregation of Revenue [Line Items]        
Total revenues 1,885 1,410 3,763 2,761
GES | Subcontractor        
Disaggregation of Revenue [Line Items]        
Total revenues 266 170 518 343
GES | Cost-plus-fee        
Disaggregation of Revenue [Line Items]        
Total revenues 1,388 1,052 2,769 2,087
GES | Fixed-price        
Disaggregation of Revenue [Line Items]        
Total revenues 476 388 948 742
GES | Time-and-materials        
Disaggregation of Revenue [Line Items]        
Total revenues 287 140 564 275
GES | Department of Defense and U.S. Intelligence Community        
Disaggregation of Revenue [Line Items]        
Total revenues 1,070 1,030 2,116 1,982
GES | Other U.S. Government Agencies        
Disaggregation of Revenue [Line Items]        
Total revenues 585 398 1,185 771
GES | Commercial and International        
Disaggregation of Revenue [Line Items]        
Total revenues $ 496 $ 152 $ 980 $ 351
v3.25.1
Revenues - Schedule of Changes in Estimated Contract Earnings (Details) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Revenue from Contract with Customer [Abstract]        
Favorable earnings at completion adjustments $ 48 $ 28 $ 68 $ 23
Unfavorable earnings at completion adjustments (27) (9) (40) (7)
Net favorable adjustments $ 21 $ 19 $ 28 $ 16
Impact on diluted earnings per share attributable to common shareholders (in dollars per share) $ 0.07 $ 0.17 $ 0.09 $ 0.14
v3.25.1
Revenues - Narrative (Details)
$ in Billions
Mar. 28, 2025
USD ($)
Disaggregation of Revenue [Line Items]  
Revenue, remaining performance obligation, amount $ 10.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-03-29 | Reamining Performance Obligation Period 1  
Disaggregation of Revenue [Line Items]  
Revenue, remaining performance obligation, percentage 72.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period 12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-03-29 | Reamining Performance Obligation Period 2  
Disaggregation of Revenue [Line Items]  
Revenue, remaining performance obligation, percentage 87.00%
Revenue, remaining performance obligation, expected timing of satisfaction, period 24 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-03-27  
Disaggregation of Revenue [Line Items]  
Revenue, remaining performance obligation, expected timing of satisfaction, period
v3.25.1
Contract Balances - Schedule of Contract Balance (Details) - USD ($)
$ in Millions
Mar. 28, 2025
Sep. 27, 2024
Capitalized Contract Cost [Line Items]    
Contract assets $ 910 $ 986
Long-term contract assets 138 138
Contract liabilities - deferred revenues and other contract liabilities (112) (113)
Nonrelated Party    
Capitalized Contract Cost [Line Items]    
Accounts receivable, net 1,556 1,378
Equity Method Investee    
Capitalized Contract Cost [Line Items]    
Accounts receivable, net $ 43 $ 37
v3.25.1
Contract Balances - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Revenue from Contract with Customer [Abstract]        
Revenue recognized $ 8 $ 6 $ 73 $ 82
v3.25.1
Sales of Receivables - Narrative (Details)
$ in Millions
Dec. 30, 2024
USD ($)
Transfers and Servicing of Financial Assets [Abstract]  
Maximum amount of receivables sold (up to) $ 400
Increase in receivables $ 150
v3.25.1
Sales of Receivables - Schedule of MARPA Activity (Details) - USD ($)
$ in Millions
 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Transfer Of Financial Assets Accounted For As Sales [Roll Forward]    
Beginning balance: $ 177 $ 0
Sales of receivables 1,955 50
Cash collections (1,912) 0
Outstanding balance sold to Purchaser 220 50
Cash collected, not remitted to Purchaser (44) (14)
Remaining sold receivables 176 36
Net cash inflow from sold receivables $ 43 $ 50
v3.25.1
Goodwill and Intangible Assets - Schedule of Changes in the Carrying Amount of Goodwill (Details)
$ in Millions
 6 Months Ended
Mar. 28, 2025
USD ($)
Goodwill [Roll Forward]  
Goodwill, beginning balance $ 5,556
Measurement period adjustments 102
Goodwill, ending balance 5,658
DS  
Goodwill [Roll Forward]  
Goodwill, beginning balance 2,412
Measurement period adjustments 4
Goodwill, ending balance 2,416
GES  
Goodwill [Roll Forward]  
Goodwill, beginning balance 3,144
Measurement period adjustments 98
Goodwill, ending balance $ 3,242
v3.25.1
Goodwill and Intangible Assets - Schedule of Intangible Assets, Net (Details) - USD ($)
$ in Millions
Mar. 28, 2025
Sep. 27, 2024
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Value $ 3,706 $ 3,735
Accumulated Amortization (1,353) (1,112)
Total intangible assets, net 2,353 2,623
Backlog    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Value 936 931
Accumulated Amortization (704) (552)
Total intangible assets, net 232 379
Customer relationship intangible assets    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Value 2,746 2,781
Accumulated Amortization (638) (550)
Total intangible assets, net 2,108 2,231
Capitalized software    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Value 24 23
Accumulated Amortization (11) (10)
Total intangible assets, net $ 13 $ 13
v3.25.1
Goodwill and Intangible Assets - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Goodwill and Intangible Assets Disclosure [Abstract]        
Amortization expense $ 120 $ 58 $ 240 $ 114
v3.25.1
Income Taxes (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Income Tax Disclosure [Abstract]        
Effective tax rate 91.70% (90.90%) 66.70% (72.30%)
Increase in the valuation allowance against deferred tax assets $ 17 $ 21 $ 28 $ 44
v3.25.1
Debt - Schedule of Debt (Details) - USD ($)
$ in Millions
Mar. 28, 2025
Sep. 27, 2024
Debt Instrument [Line Items]    
Total debt $ 4,762 $ 4,767
Unamortized original issue discount and unamortized deferred financing costs (83) (88)
Total debt, net of original issue discount and deferred financing costs 4,679 4,679
Less current portion of long-term debt (43) (36)
Long-term debt, net of current portion 4,636 4,643
Senior notes    
Debt Instrument [Line Items]    
Total debt 1,000 1,000
Other    
Debt Instrument [Line Items]    
Total debt 12 17
Term Loan | Secured Debt | Line of Credit    
Debt Instrument [Line Items]    
Total debt $ 3,750 $ 3,750
v3.25.1
Debt - Narrative (Details) - USD ($)
 6 Months Ended
Mar. 28, 2025
Sep. 27, 2024
Aug. 31, 2024
Interest Rate Swap      
Line of Credit Facility [Line Items]      
Derivative, notional amount $ 1,900,000,000    
Line of Credit | Secured Debt      
Line of Credit Facility [Line Items]      
Periodic payment, principal $ 9,000,000    
Line of Credit | Credit Agreement | Secured Debt      
Line of Credit Facility [Line Items]      
Debt instrument, term 7 years    
Line of credit facility, maximum borrowing capacity $ 3,750,000,000    
Line of Credit | Credit Agreement | Revolving Credit Facility      
Line of Credit Facility [Line Items]      
Debt instrument, term 5 years    
Line of credit facility, maximum borrowing capacity $ 850,000,000    
Line of Credit | Credit Agreement | Letter of Credit      
Line of Credit Facility [Line Items]      
Line of credit facility, maximum borrowing capacity 200,000,000    
Line of Credit | Credit Agreement | Bridge Loan      
Line of Credit Facility [Line Items]      
Line of credit facility, maximum borrowing capacity 100,000,000    
Line of Credit | New Credit Facility      
Line of Credit Facility [Line Items]      
Line of credit facility, remaining borrowing capacity 775,000,000 $ 808,000,000  
Line of Credit | New Credit Facility | Letter of Credit      
Line of Credit Facility [Line Items]      
Line of credit facility, remaining borrowing capacity $ 75,000,000 $ 42,000,000  
Senior notes      
Line of Credit Facility [Line Items]      
Debt instrument, face amount     $ 1,000,000,000
Debt instrument, interest rate, stated percentage     7.25%
v3.25.1
Joint Ventures - Schedule of Condensed Financial Statements (Details) - USD ($)
$ in Millions
Mar. 28, 2025
Dec. 27, 2024
Sep. 27, 2024
Mar. 29, 2024
Dec. 29, 2023
Sep. 29, 2023
Variable Interest Entity [Line Items]            
Cash and cash equivalents $ 546   $ 452      
Total assets 12,004   11,974      
Current liabilities 2,097   1,965      
Total liabilities 7,425   7,422      
Total Amentum equity 4,427   4,460      
Non-controlling interests 152   92      
Total shareholders' equity 4,579 $ 4,563 4,552 $ 324 $ 358 $ 416
Total liabilities and shareholders' equity 12,004   11,974      
Variable Interest Entity, Primary Beneficiary            
Variable Interest Entity [Line Items]            
Cash and cash equivalents 143   160      
Current assets 325   322      
Non-current assets 3   2      
Total assets 471   484      
Current liabilities 169   190      
Non-current liabilities 1   1      
Total liabilities 170   191      
Total Amentum equity 231   228      
Non-controlling interests 70   65      
Total shareholders' equity 301   293      
Total liabilities and shareholders' equity $ 471   $ 484      
v3.25.1
Joint Ventures - Schedule of Condensed Income Statement (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Variable Interest Entity [Line Items]        
Revenues $ 3,491 $ 2,051 $ 6,907 $ 4,034
Cost of revenues (3,124) (1,851) (6,179) (3,640)
Net income including non-controlling interests 2 (42) 23 (81)
Variable Interest Entity, Primary Beneficiary        
Variable Interest Entity [Line Items]        
Revenues 367 67 743 136
Cost of revenues (331) (57) (667) (115)
Net income including non-controlling interests $ 36 $ 10 $ 75 $ 20
v3.25.1
Joint Ventures - Narrative (Details)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
USD ($)
investment
Mar. 29, 2024
USD ($)
Mar. 28, 2025
USD ($)
investment
Mar. 29, 2024
USD ($)
Sep. 27, 2024
USD ($)
Variable Interest Entity [Line Items]          
Number of active joint ventures (more than) | investment 20   20    
Revenues $ 3,491 $ 2,051 $ 6,907 $ 4,034  
Maximum exposure to losses 193   193    
Equity Method Investee          
Variable Interest Entity [Line Items]          
Related party receivables due from our equity method investments 43   43   $ 37
Revenues $ 45 $ 17 $ 89 $ 33  
Joint Ventures Investment | Minimum          
Variable Interest Entity [Line Items]          
Ownership percentage 10.00%   10.00%    
Joint Ventures Investment | Maximum          
Variable Interest Entity [Line Items]          
Ownership percentage 51.00%   51.00%    
v3.25.1
Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Other comprehensive (loss) income before reclassification, tax $ 2 $ (3) $ (2) $ 1
Amounts reclassified from accumulated other comprehensive (loss) income, tax 0 1 0 1
Beginning balance 4,563 358 4,552 416
Other comprehensive (loss) income, before reclassifications 7 13 10 (4)
Amounts reclassified from accumulated other comprehensive (loss) income (1) (3) (4) (5)
Ending balance 4,579 324 4,579 324
Accumulated Other Comprehensive Income        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance, tax (17) (14) (13) (18)
Ending balance, tax (15) (16) (15) (16)
Beginning balance 23 29 23 48
Ending balance 29 39 29 39
Gain (Loss) on Derivative Instruments        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance, before tax 0 (4) (22) 25
Other comprehensive (loss) income before reclassification and taxes (6) 18 19 (9)
Amounts reclassified from accumulated other comprehensive (loss) income, before tax (1) (3) (4) (5)
Ending balance before tax (7) 11 (7) 11
Foreign Currency Translation Adjustments        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance, before tax (15) 1 3 (5)
Other comprehensive (loss) income before reclassification and taxes 11 (2) (7) 4
Amounts reclassified from accumulated other comprehensive (loss) income, before tax 0 0 0 0
Ending balance before tax (4) (1) (4) (1)
Pension Related Adjustments        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance, before tax 55 46 55 46
Other comprehensive (loss) income before reclassification and taxes 0 0 0 0
Amounts reclassified from accumulated other comprehensive (loss) income, before tax 0 (1) 0 (1)
Ending balance before tax $ 55 $ 45 $ 55 $ 45
v3.25.1
Segment Information - Narrative (Details) - segment
 3 Months Ended 6 Months Ended
Dec. 27, 2024
Mar. 28, 2025
Segment Reporting [Abstract]    
Number of reportable segments 2 2
v3.25.1
Segment Information - Schedule of Segment Revenues (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Segment Reporting Information [Line Items]        
Revenues $ 3,491 $ 2,051 $ 6,907 $ 4,034
DS        
Segment Reporting Information [Line Items]        
Revenues 1,340 471 2,626 930
GES        
Segment Reporting Information [Line Items]        
Revenues $ 2,151 $ 1,580 $ 4,281 $ 3,104
v3.25.1
Segment Information - Schedule of Adjusted EBITDA to Net Income (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Segment Reporting Information [Line Items]        
Adjusted EBITDA attributable to Amentum Holdings, Inc. $ 268 $ 156 $ 530 $ 310
Depreciation expense (9) (5) (18) (12)
Amortization of intangibles (120) (58) (240) (114)
Interest expense and other, net (86) (111) (173) (222)
Non-controlling interests (2) (1) 7 1
Acquisition, transaction and integration costs (21) (4) (30) (11)
Utilization of fair market value adjustments (1) 2 1 3
Share-based compensation (5) (1) (8) (2)
Income (loss) before income taxes 24 (22) 69 (47)
Provision for income taxes (22) (20) (46) (34)
Net income (loss) including non-controlling interests 2 (42) 23 (81)
Non-controlling interests 2 1 (7) (1)
Net income (loss) attributable to common shareholders 4 (41) 16 (82)
DS        
Segment Reporting Information [Line Items]        
Adjusted EBITDA attributable to Amentum Holdings, Inc. 107 40 207 78
GES        
Segment Reporting Information [Line Items]        
Adjusted EBITDA attributable to Amentum Holdings, Inc. $ 161 $ 116 $ 323 $ 232
v3.25.1
Earnings (Loss) Per Share - Narrative (Details) - shares
 3 Months Ended 6 Months Ended
Mar. 29, 2024
Mar. 29, 2024
Earnings Per Share [Abstract]    
Converted shares (in shares) 90,021,804 90,021,804
Anti-dilutive shares (in shares) 0 0
v3.25.1
Earnings (Loss) Per Share - Schedule of Basic and Diluted Loss Per Share (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Mar. 28, 2025
Mar. 29, 2024
Mar. 28, 2025
Mar. 29, 2024
Earnings Per Share [Abstract]        
Net income (loss) attributable to common shareholders $ 4 $ (41) $ 16 $ (82)
Weighted-average number of basic shares outstanding during the period (in shares) 243 90 243 90
Weighted-average number of diluted shares outstanding during the period (in shares) 243 90 243 90
Basic earnings (loss) per share (in dollars per share) $ 0.02 $ (0.46) $ 0.07 $ (0.91)
Diluted earnings (loss) per share (in dollars per share) $ 0.02 $ (0.46) $ 0.07 $ (0.91)
v3.25.1
Legal Proceedings and Commitments and Contingencies (Details) - USD ($)
$ in Millions
 1 Months Ended
Jan. 31, 2020
Mar. 28, 2025
Loss Contingencies [Line Items]    
Estimate of possible loss   $ 138
Other long-term liabilities   $ 125
AECOM Energy & Construction Inc.    
Loss Contingencies [Line Items]    
Percentage of claim recovery and costs assumed 10.00%  
Percentage of claim recovery and costs retained by seller 90.00%  
v3.25.1
Subsequent Event (Details)
$ in Millions
Apr. 23, 2025
USD ($)
Subsequent Event | Disposal Group, Disposed of by Sale, Not Discontinued Operations | Rapid Solutions  
Subsequent Event [Line Items]  
Expected purchase price $ 360