CULLEN/FROST BANKERS, INC., 11-K filed on 3/27/2026
Annual Report of Employee Stock Plans
v3.26.1
Cover
 12 Months Ended
Dec. 31, 2025
Cover [Abstract]  
Document Type 11-K
Entity Registrant Name CULLEN/FROST BANKERS, INC.
Entity Central Index Key 0000039263
Amendment Flag false
v3.26.1
Employee Benefit Plan, Statement of Net Asset Available for Benefit (Statement) - EBP Thrift - USD ($)
$ in Thousands
Dec. 31, 2025
Dec. 31, 2024
EBP, Statement of Net Asset Available for Benefit [Line Items]    
EBP, Asset $ 0 $ 0
EBP, Liability 0 0
EBP, Net Asset Available for Benefit 0 0
Total liabilities and plan equity $ 0 $ 0
v3.26.1
Employee Benefit Plan, Statement of Change in Net Asset Available for Benefit (Statement) - EBP Thrift - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
EBP, Statement of Change in Net Asset Available for Benefit [Line Items]      
EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash $ 187 $ 174 $ 169
EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution 187 174 169
EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment 4 3 4
EBP, Change in Net Asset Available for Benefit, Increase from Realized Gain on Investment 10 46 30
EBP, Change in Net Asset Available for Benefit, Increase from Contribution 388 397 372
EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant 388 397 372
EBP, Change in Net Asset Available for Benefit, Decrease 388 397 372
EBP, Change in Net Asset Available for Benefit, Increase (Decrease) 0 0 0
EBP, Net Asset Available for Benefit, Beginning Balance 0 0 0
EBP, Net Asset Available for Benefit, Ending Balance $ 0 $ 0 $ 0
v3.26.1
Employee Benefit Plan, Summary of Accounting Policy
 12 Months Ended
Dec. 31, 2025
EBP Thrift  
EBP, Accounting Policy [Line Items]  
EBP, Summary of Accounting Policy Significant Accounting Policies
Basis of Presentation. The financial statements of the Thrift Incentive Stock Purchase Plan for Certain Employees of Cullen/Frost Bankers, Inc. (the “Plan”) are presented on the accrual basis of accounting. Cullen/Frost Bankers, Inc., and its affiliates are herein referred to collectively as “Cullen/Frost”.
Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates that affect amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Investments. All contributions to the Plan are invested in the common stock of Cullen/Frost, which is purchased at fair value based on quoted market prices as of the purchase date. The Plan also invests, temporarily, in money market mutual funds. Investments are stated at fair value based on quoted market prices on the valuation date. Purchases and sales of securities are recorded on the settlement date, which generally does not materially differ from the trade date. Gains and losses on the sale or transfer of investments are based on the cost of the specific securities sold or transferred in-kind. Dividends are recorded on the ex-dividend date. Interest is recorded on the accrual basis.
Administrative Expenses and Related-Party Transactions. Certain administrative functions are performed by Cullen/Frost employees; however, none of these employees receive compensation from the Plan. Cullen/Frost also directly pays for certain other administrative expenses.
v3.26.1
Employee Benefit Plan, Description of Plan
 12 Months Ended
Dec. 31, 2025
EBP Thrift  
EBP, Description of Plan [Line Items]  
EBP, Description of Plan Description of the Plan
General. The Plan is a non-qualified contributory plan. In addition to the Plan, Cullen/Frost maintains the 401(k) Stock Purchase Plan for Employees of Cullen/Frost Bankers, Inc. and Its Affiliates (the “401(k) Plan”). The Plan covers certain employees who have been deemed eligible for participation. The Plan is intended to provide current compensation that is reasonably comparable to other benefits the participant would be able to receive during a relevant plan year under the 401(k) Plan if it were not for limitations imposed by certain sections of the Internal Revenue Code (the “Code”).
Contributions. For each plan year, each active participant is eligible to contribute an amount equal to 7% of their compensation in excess of the maximum annual compensation limit in effect under Code section 401(a)(17)(A) for the plan year. Further, each participant who also participates in the 401(k) Plan will be assumed to have made pre-tax deferrals equal to the Code section 402(g) limit in effect for that plan year. Cullen/Frost's administrative committee determines at such times as the Code limitations are applied under the 401(k) Plan. The Plan is not designed to provide deferred compensation and is intended to be exempt from Section 409A of the Code.
For each plan year, Cullen/Frost makes contributions equal to 100% of each participant’s after-tax contributions to the Plan for the respective plan year.
Vesting. Participants are immediately vested 100% in their accounts, which are distributed to each participant annually.
Investment Options. All contributions from both the Plan participants and Cullen/Frost are invested in Cullen/Frost common stock.
Payment of Benefits. In general, all Plan equity is distributed on an annual basis by the end of each plan year, including dividend and interest income and net unrealized appreciation/depreciation in the fair value of investments earned during the year. Assets are transferred into brokerage and checking accounts in the names of each individual participant.
Plan Termination. Although it has not expressed any present intent to do so, Cullen/Frost has the right under the Plan to discontinue its contributions at any time and to terminate the Plan.
v3.26.1
Employee Benefit Plan, Contribution
 12 Months Ended
Dec. 31, 2025
EBP Thrift  
EBP, Contribution [Line Items]  
EBP, Contribution Investments
The Plan’s investments in common stock of Cullen/Frost appreciated in value by $10 thousand, $46 thousand, and $30 thousand in 2025, 2024, and 2023, respectively. These amounts are reported as net realized gain on sale of investments and appreciation on in-kind transfers of investments to participants in the Plan’s financial statements as the common stock is transferred at cost at the end of each plan year. A summary of net realized gain on sale of investments and appreciation on in-kind transfers of investments is as follows:
202520242023
Aggregate proceeds$384 $394 $368 
Less: Aggregate cost(374)(348)(338)
Net realized gain/(loss) on sale of investments and appreciation/(depreciation) on in-kind transfers of investments to participants
$10 $46 $30 
v3.26.1
Employee Benefit Plan, Tax Status
 12 Months Ended
Dec. 31, 2025
EBP Thrift  
EBP, Tax Status [Line Items]  
EBP, Tax Status Income Tax Status
The Plan is not subject to federal income taxes as all contributions to the Plan and earnings are fully vested and treated as taxable to the employee. All employee contributions to the Plan are made on an after-tax basis. Employer contributions to the Plan are not deferred and therefore are included in the employee’s taxable income.
v3.26.1
Employee Benefit Plan, Fair Value and NAV
 12 Months Ended
Dec. 31, 2025
EBP Thrift  
EBP, Investment, Fair Value and NAV [Line Items]  
EBP, Investment, Fair Value and NAV Fair Value Measurements
The fair value of an asset or liability is the price that would be received to sell that asset or paid to transfer that liability in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. Accounting Standards Codification (ASC) Topic 820 “Fair Value Measurements and Disclosures” establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy includes (i) Level 1 inputs  that are unadjusted quoted prices in active markets for identical assets or liabilities, (ii) Level 2 inputs that are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly and (iii) Level 3 inputs that are unobservable inputs for determining the fair values of assets or liabilities that reflect assumptions that market participants would use in pricing the assets or liabilities.
All investments held by the Plan during the reported periods were considered Level 1 investments under the fair value hierarchy as fair value is based on quoted prices in active markets.
v3.26.1
Employee Benefit Plan, Summary of Accounting Policy (Policies) - EBP Thrift
 12 Months Ended
Dec. 31, 2025
EBP, Accounting Policy [Line Items]  
EBP, Basis of Accounting
Basis of Presentation. The financial statements of the Thrift Incentive Stock Purchase Plan for Certain Employees of Cullen/Frost Bankers, Inc. (the “Plan”) are presented on the accrual basis of accounting. Cullen/Frost Bankers, Inc., and its affiliates are herein referred to collectively as “Cullen/Frost”.
EBP, Use of Estimate
Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates that affect amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
EBP, Investment
Investments. All contributions to the Plan are invested in the common stock of Cullen/Frost, which is purchased at fair value based on quoted market prices as of the purchase date. The Plan also invests, temporarily, in money market mutual funds. Investments are stated at fair value based on quoted market prices on the valuation date. Purchases and sales of securities are recorded on the settlement date, which generally does not materially differ from the trade date. Gains and losses on the sale or transfer of investments are based on the cost of the specific securities sold or transferred in-kind. Dividends are recorded on the ex-dividend date. Interest is recorded on the accrual basis.
EBP, Expense
Administrative Expenses and Related-Party Transactions. Certain administrative functions are performed by Cullen/Frost employees; however, none of these employees receive compensation from the Plan. Cullen/Frost also directly pays for certain other administrative expenses.
v3.26.1
Employee Benefit Plan, Contribution (Tables)
 12 Months Ended
Dec. 31, 2025
EBP Thrift  
EBP, Contribution [Line Items]  
EBP, Contribution A summary of net realized gain on sale of investments and appreciation on in-kind transfers of investments is as follows:
202520242023
Aggregate proceeds$384 $394 $368 
Less: Aggregate cost(374)(348)(338)
Net realized gain/(loss) on sale of investments and appreciation/(depreciation) on in-kind transfers of investments to participants
$10 $46 $30 
v3.26.1
Employee Benefit Plan, Description of Plan (Details) - Additional Information - EBP Thrift
 12 Months Ended
Dec. 31, 2025
EBP, Description of Plan [Line Items]  
EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage 7.00%
EBP, Employer Contribution, Matching Percentage 100.00%
v3.26.1
Employee Benefit Plan, Contribution (Details) - EBP Thrift - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
EBP, Contribution [Line Items]      
EBP, Investment Sold, Aggregate Proceeds $ 384 $ 394 $ 368
EBP, Investment Sold, Aggregate Cost (374) (348) (338)
EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Realized Gain (Loss) on Investment $ 10 $ 46 $ 30