阿莱恩斯西部银行 2025年度报告

For the fiscal year ended December 31, 2025 ☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934For the transition period from ____________ to ____________Commission file number: 001-32550 WESTERN ALLIANCE BANCORPORATION (Exact name of registrant as specified in its charter) Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.Yes☒No☐ Indicate by check mark if the registrant is not required to file reports pursuant to Section13 or Section15(d) of the Act.Yes☐No☒ Indicate by check mark whether the registrant (1)has filed all reports required to be filed by Section13 or 15(d) of the Securities Exchange Act of 1934 during thepreceding 12months (or for such shorter period that the registrant was required to file such reports), and (2)has been subject to such filing requirements for the past90days.Yes☒No☐ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule405 of RegulationS-T(§232.405 of this chapter) during the preceding 12months (or for such shorter period that the registrant was required to submit such files).Yes☒No☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, or emerging growthcompany. See the definitions of “large accelerated filer,” "accelerated filer" "smaller reporting company," and "emerging growth company" in Rule 12b-2 of theExchange Act. Large accelerated filer☒Non-accelerated filer☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revisedfinancial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐ Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control overfinancial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒ If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect thecorrection of an error to previously issued financial statements.☐ Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of theregistrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b).☐ Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).Yes☐No☒ The aggregate market value of the registrant’s voting stock held by non-affiliates was approximately $8.36 billion based on the June 30, 2025 closing price of said stockon the New York Stock Exchange ($77.98 per share). As of February18, 2026, Western Alliance Bancorporation had 109,879,137 shares of common stock outstanding. DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement for its 2026 Annual Meeting of Stockholders are incorporated by reference into Part III of this report. INDEX PART I Forward-Looking StatementsItem 1.BusinessItem 1A.Risk FactorsItem 1B.Unresolved Staff CommentsItem 1C.CybersecurityItem 2.PropertiesItem 3.Legal ProceedingsItem 4.Mine Safety Disclosures PARTII Item5.Market for the Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of EquitySecurities33Item6.Reserved34Item7.Management's Discussion and Analysis of Financial Condition and Results of Operations35Item 7A.Quantitative and Qualitative Disclosures About Market Risk74Item 8.Financial Statements and Supplementary Data76Item 9.Changes in and Disagreements with Accountants on Accounting and Financial Disclosure161Item 9A.Controls and Procedures161Item 9B.Other Information163Item 9C.Disclosure Regarding Foreign Jurisdictions that Prevent Inspections163 PART III Item 10.Directors, Executive Officers and Corporate Governance163Item 11.Executive Compensation163Item 12.Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters163Item 13.Certain Relationships and Related Transactions, and Director Independence163Item 14.Principal Accountant Fees and Services163 PART IV Item 15.Exhibits and Financial Statement Schedules164Item 16.Form 10-K Summary166 SIGNATURES Table of Contents PART I Forward-Looking Statements Certain statements contained in this Annual Report on Form 10-K for the fiscal year ended December 31, 2025 (this “Form 10-K”) are“forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995 (the “Reform Act”).Statements that constitute forward-looking statements within the meaning