德尼克斯投资美股招股说明书(2026-07-28版)

99,326,438 shares Dynex Capital, Inc. Common stock We have entered into Amendment No. 10 to the distribution agreement, dated June 29, 2018, as amended May 31, 2019, August 3, 2021, June 3, 2022, February 10,2023, October 29, 2024, May 1, 2025, July 29, 2025, January 27, 2026, April 28, 2026, and July 28, 2026 (collectively, the “Distribution Agreement”), with BTIG, LLC,Citizens JMP Securities, LLC, Goldman Sachs & Co. LLC, JonesTrading Institutional Services LLC, J.P. Morgan Securities LLC, Keefe, Bruyette & Woods, Inc.,Morgan Stanley & Co. LLC, RBC Capital Markets, LLC, UBS Securities LLC, and Wells Fargo Securities, LLC (collectively, the “Sales Agents” and each, individually,a “Sales Agent”) relating to shares of our common stock, par value $0.01 per share (our “common stock”), offered by this prospectus supplement and the accompanyingbase prospectus (together, the “prospectus”) pursuant to a continuous offering program. In accordance with the terms of the Distribution Agreement, we may offer andsell up to 301,292,973 shares of our common stock from time to time through the Sales Agents, acting as our sales agents, or directly to the Sales Agents, acting asprincipals. We had previously registered an aggregate of 67,354,187 shares of our common stock, offered by means of a 424(b)(5) prospectus supplement, dated January27, 2026, as supplemented on April 28, 2026 (the “prior prospectus supplement”). As of the date of this prospectus supplement, we have sold 48,027,749 shares of ourcommon stock pursuant to the prior prospectus supplement under the Distribution Agreement. The offering pursuant to the prior prospectus supplement has terminated.As of the date of this prospectus supplement, we have issued 201,966,535 shares of common stock pursuant to the Distribution Agreement, and we have 99,326,438authorized shares of common stock available for issuance under the Distribution Agreement from and after the date hereof. Our common stock is listed on the New YorkStock Exchange (the “NYSE”) under the symbol “DX.” The last reported sale price of our common stock on the NYSE on July 27, 2026 was $12.64 per share. Sales of our common stock, if any, pursuant to this prospectus supplement and the accompanying base prospectus will be made in sales deemed to be “at the marketofferings” as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended (the “Securities Act”), by means of ordinary brokers’ transactions on the NYSE orotherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. The Sales Agents are not required to sell anyspecific number or dollar amount of our common stock, but each Sales Agent will use its commercially reasonable efforts consistent with its normal trading and salespractices and applicable law and regulation to sell shares designated by us in accordance with the Distribution Agreement. We will pay each Sales Agent a commission of up to 2.0% of the gross sales price of the shares of our common stock sold by such Sales Agent pursuant to thisprospectus supplement and the accompanying base prospectus. In connection with the sale of the shares of common stock on our behalf, each of the Sales Agents maybe deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of each Sales Agent may be deemed to be underwriting commissionsor discounts. The net proceeds we receive will be the gross proceeds received from such sales less the commissions and any other costs we may incur in issuing theshares of our common stock. There is no arrangement for funds to be received in an escrow, trust or similar arrangement. See “Plan of Distribution” elsewhere in thisprospectus supplement for further information. Under the terms of the Distribution Agreement, we may also sell shares of our common stock to any of the Sales Agents, acting as principal, at a price per share to beagreed upon at the time of sale. If we sell shares to a Sales Agent acting as principal, we will enter into a separate terms agreement with that Sales Agent. In order to preserve our status as a real estate investment trust (“REIT”) for federal income tax purposes, among other purposes, our articles of incorporation imposecertain restrictions on ownership and transfer of our common stock. See “Description of Our Capital Stock—Restrictions on Ownership and Transfer” in theaccompanying base prospectus for further information. Investing in our common stock involves certain risks. Before buying any shares, you should read the discussion of material risks of investing in our commonstock under the caption “Risk Factors”beginning on pageS-4of this prospectus supplement, as well as those described in our most recent Annual Report onForm 10-K, any Quarterly Reports on Form 10-Q filed after such Annual Report on Form 10-K and in other information that we file from time to time withthe Securities and Exchange Commission (the “SEC”). Neith