COF: Other company developments

Item 8.01 Other Events. This current report on Form 8-K is filed for the purpose of filing the attached exhibit in connection with the prospectus supplement no. 2, dated June 9, 2026 (the “Resale Prospectus Supplement No. 2”), filed by Capital One Financial Corporation (the “Company”) with the Securities and Exchange Commission, which amends and supplements the prospectus supplement, dated April 23, 2026 (the “Initial Resale Prospectus Supplement”) and forms a part of the Company’s automatic shelf registration statement on Form S-3 (File No. 333-277813). The Resale Prospectus Supplement No. 2 registers the offer and sale of an additional 39,843 shares of common stock, $0.01 par value per share, of the Company (“Company Common Stock”). The Company previously registered the offer and sale of up to 10,345,906 shares of Company Common Stock under the Initial Resale Prospectus Supplement. Accordingly, the selling security holders referred to in the Initial Resale Prospectus Supplement, as amended and supplemented by the Resale Prospectus Supplement No. 2, may offer and sell up to 10,385,749 shares of Company Common Stock. The Company issued these shares of Company Common Stock to the selling security holders as consideration in connection with the Company’s acquisition of Brex Inc., which closed on April 7, 2026. Item 9.01 Financial Statements and Exhibits. (d) Exhibits Exhibit No. Description 5.1 Opinion of Wachtell, Lipton, Rosen & Katz 23.1 Consent of Wachtell, Lipton, Rosen & Katz (included in Exhibit 5.1) 104 The cover page from this Current Report on Form 8-K, formatted in Inline XBRL SIGNATURE Pursuant to the requirements of the Securities Exchange Act of 1934, the Company has duly caused this Current Report on Form 8-K to be signed on its behalf by the undersigned he