第一资本金融美股招股说明书(2026-04-23版)

10,345,906 Shares Common Stock The selling security holders referred to in this prospectus supplement (the “selling security holders”) may offer and sell up to 10,345,906 shares ofour common stock, $0.01 par value per share (“common stock”) under this prospectus supplement. We issued these shares of common stock to theselling security holders as consideration in connection with our acquisition of Brex Inc. (“Brex”), which closed on April7, 2026. These shares ofcommon stock were issued to the selling security holders pursuant to an Agreement and Plan of Merger and Reorganization, dated as of January22,2026 (as it may be amended, supplemented, restated or otherwise modified from time to time, the “Brex Merger Agreement”), by and among CapitalOne Financial Corporation, a Delaware corporation (“Capital One”), Brex, a Delaware corporation, Trilogy Merger Sub I, Inc., a Delaware corporationand a direct wholly owned subsidiary of Capital One (“Trilogy Merger Sub I”), Trilogy Merger Sub II, LLC, a Delaware limited liability company and adirect wholly owned subsidiary of Capital One (“Trilogy Merger Sub II”), and, solely for the limited purposes set forth therein, Fortis Advisors LLC, aDelaware limited liability company (“Fortis Advisors”). Our registration of the shares of common stock covered by this prospectus supplement does not mean that the selling security holders will offer orsell any of the shares. The common stock offered by the selling security holders may be sold from time to time through public or private transactions atmarket prices prevailing at the time of sale, at prices related to such market prices, at varying prices determined at the time of sale, at fixed prices, or atnegotiated prices. The timing and amount of any sale is within the sole discretion of the selling security holder, subject to certain restrictions underapplicable securities laws. See the section entitled “Plan of Distribution” beginning on pageS-13 of this prospectus supplement for more information. We are not selling any shares of common stock under the prospectus supplement and we will not receive any proceeds from any sale of shares ofcommon stock by the selling security holders. Our common stock is listed on the New York Stock Exchange (“NYSE”) under the trading symbol“COF.” On April22, 2026, the last reported sale price of our common stock was $199.43 per share. Investing in our common stock involves risks. You should review carefully this prospectus supplement, the accompanying prospectus, therisks and uncertainties described in the section titled “Risk Factors” beginning on page S-7 of this prospectus supplement, as well as our otherfilings that are incorporated by reference into this prospectus supplement and the accompanying prospectus. Neither the Securities and Exchange Commission (the “SEC”) nor any state securities commission has approved or disapproved of thesesecurities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to thecontrary is a criminal offense. The shares of common stock are not savings accounts, deposits or other obligations of a bank and are not insured or guaranteed by theFederal Deposit Insurance Corporation (the “FDIC”) or any other governmental agency or instrumentality. Table of Contents TABLE OF CONTENTS Prospectus Supplement About This Prospectus SupplementForward-looking StatementsSummaryRisk FactorsUse of ProceedsSelling Security HoldersPlan of DistributionValidity of the Shares of Common StockExpertsWhere You Can Find More Information Prospectus About This ProspectusForward-Looking StatementsWhere You Can Find More InformationUse of ProceedsRisk FactorsDescription of Debt SecuritiesDescription of Preferred StockDescription of Common StockDescription of Other SecuritiesResale by Selling SecurityholdersBook-Entry Procedures and SettlementCertain Legal Matters Experts We have not, and the selling security holders have not, authorized any other person to provide you with information different from, or inaddition to, that contained in or incorporated by reference in this prospectus supplement (including any related free writing prospectusprepared by us or on our behalf, if any) and the accompanying prospectus. We and the selling security holders take no responsibility for, andcan provide no assurance as to the reliability of, any other information that others may give you. We are not, and the selling security holders arenot, making an offer to sell the common stock in any jurisdiction where the offer or sale is not permitted. You should assume that theinformation appearing in this prospectus supplement (including any related free writing prospectus prepared by us or on our behalf, if any), theaccompanying prospectus and the documents incorporated by reference herein and therein, is accurate only as of their respective dates. Ourbusiness, financial condition, results of operations and prospects may have changed sinc