Dynex Capital, Inc.

Item 1.01. Entry into a Material Definitive Agreement. On September 22, 2026, Dynex Capital, Inc. (the “Company”), entered into an underwriting agreement (the “Underwriting Agreement”) with Morgan Stanley & Co. LLC, J.P. Morgan Securities LLC, RBC Capital Markets, LLC, UBS Securities LLC, Wells Fargo Securities, LLC, Citigroup Global Markets Inc., Goldman Sachs & Co. LLC and Keefe, Bruyette & Woods, Inc., acting as representatives of the several underwriters listed on Schedule 1 thereto (collectively, the “Underwriters”), pursuant to which the Company agreed to issue and sell an aggregate of 4,800,000 shares (the “Underwritten Shares”) of 9.375% Series D Fixed-Rate Cumulative Redeemable Preferred Stock (the “Series D Preferred Stock”), par value $0.01 per share, with a liquidation preference of $25.00 per share, in an underwritten public offering (the “Offering”). Pursuant to the Underwriting Agreement, the Company also granted the Underwriters a 30-day option to purchase up to an additional 720,000 shares of Series D Preferred Stock on the same terms and conditions (the “Option Shares” and together with the Underwritten Shares, the “Shares”). The Shares will be established by Articles of Amendment to the Restated Articles of Incorporation of the Company. In the Underwriting Agreement, the Company made certain customary representations, warranties and covenants and agreed to indemnify the Underwriters against certain liabilities. The Offering is expected to close on or about September 29, 2026, subject to satisfaction of customary closing conditions. The Company’s total net proceeds from the Offering, after deducting the underwriting discount (before estimated expenses and assuming no exercise of the underwriters’ over-allotment option to purchase the Option Shares) are expected to be approximately $116,220,000. The Offering is being conducted pursuant to the Company’s prospectus supplement dated September 22, 2026, in the form filed with the Securities and Exchange Commission (the “SEC”) pursuant to Rule 424(b), which supplements the Company’s base prospectus dated July 28, 2025 filed with the SEC as part of the Company’s automatic shelf Registration Statement on Form S-3 (File No. 333-289004), which became effective upon filing with the SEC pursuant to Rule 462(e) under the Securities Act. The foregoing description does not purport to be a complete description and is qualified in its entirety by reference to the Underwriting Agreement, which is filed herewith as Exhibit 1.1 and incorporated by reference into this Item 1.01.

Item 7.01. Regulation FD Disclosure. On September 22, 2026, the Company issued a press release announcing the pricing of the Offering. A copy of this press release is attached as Exhibit 99.1 and is hereby incorporated by reference into this Item 7.01. This press release shall not be deemed “filed” for any purpose, including for the purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that Section. The information in Item 7.01, including Exhibit 99.1, shall not be deemed incorporated by reference into any filing under the Exchange Act or the Securities Act of 1933, regardless of any general incorporation language in such filing.