PRELIMINARY PROSPECTUS SUPPLEMENT(To Prospectus dated April 1, 2024) We initially issued 4,800,000 shares of the Series C Preferred Stock on June 10, 2014 (the “Original Shares”). Subject to the preferential rights of holders of any class or series of our senior equitysecurities, holders of Series C Preferred Stock are entitled to receive, when, as and if authorized by our Board of Directors, out of funds legally available for the payment of distributions, cumulative cash distributions.Prior to July 30, 2024, we paid such distributions at a fixed rate (the “Fixed-Rate Period”). From and including, July 30, 2024 and thereafter (the “Floating Rate Period”), holders of Series C Preferred Stock are entitled toreceive cumulative cash distributions at a floating rate equal to Three-Month Term SOFR (as defined below) as calculated on each applicable date of determination (as defined below) plus a spread of 5.927% per annumbased on the $25.00 liquidation preference, payable quarterly, in arrears, on the 30th day of January, April, July and October of each year, beginning on October 30, 2024 and thereafter, provided that such floating rateshall not be less than the initial rate of 8.625%. The Shares sold pursuant to this prospectus supplement will be fungible with and form a single series with the Original Shares under the Articles Supplementary (as definedherein) and will be identical in all respects and have the same CUSIP as the Original Shares. We may, at our option, redeem the Series C Preferred Stock, in whole or from time to time in part, by paying $25.00 per share, plus any accrued and unpaid distributions to, but excluding, the date ofredemption. In addition, upon the occurrence of a Change of Control (as defined herein), we may, at our option, redeem the Series C Preferred Stock, in whole or in part within 120 days after the first date on which suchChange of Control occurred, by paying $25.00 per share, plus any accrued and unpaid distributions to, but excluding, the date of redemption. To the extent we exercise our redemption right relating to the Series CPreferred Stock, the holders of Series C Preferred Stock will not be permitted to exercise the conversion right in connection with a Change of Control described below in respect of their shares called for redemption. TheSeries C Preferred Stock has no maturity date and will remain outstanding indefinitely unless redeemed by us or converted in connection with a Change of Control by the holders of Series C Preferred Stock. Upon the occurrence of a Change of Control, each holder of Series C Preferred Stock will have the right (subject to our right to redeem the Series C Preferred Stock in whole or in part, as described above,prior to the Change of Control Conversion Date (as defined herein)) to convert some or all of the Series C Preferred Stock held by such holder on the Change of Control Conversion Date into a number of shares of ourcommon stock per share of Series C Preferred Stock (or the equivalent value of the alternative consideration) as described in this prospectus supplement. The shares of Series C Preferred Stock are subject to certain restrictions on ownership and transfer designed to preserve our qualification as a real estate investment trust, or REIT, for federal income taxpurposes. See “Description of the Series C Preferred Stock — Restrictions on Ownership and Transfer.” Holders of the Series C Preferred Stock generally have no voting rights except for limited voting rights if we fail to pay distributions on the Series C Preferred Stock for six or more quarterly periods(whether or not consecutive) or we fail to maintain the listing of the Series C Preferred Stock on a national securities exchange for a period of at least 180 consecutive business days. The Series C Preferred Stock is listed on the New York Stock Exchange under the symbol “ACRPrC.” Investing in the Series C Preferred Stock involves a high degree of risk. You should carefully consider the risk factors referred to in the sections titled “Risk Factors”beginning on page S-7 of this prospectus supplement, page 7 of the accompanying prospectus and appearing under the caption “Item 1A. Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2025 and our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2026 and June 30, 2026, each of which are incorporated by referenceherein, as well as additional risks that may be described in future reports of information that we file with the U.S. Securities and Exchange Commission (“SEC”), which are incorporatedby reference in this prospectus supplement and the accompanying prospectus. Offering Price$$Placement Agent Fees$$Proceeds, before expenses, to us$$We have agreed (i) to pay a cash fee to the placement agent equal to 2% of the aggregate purchase of our Shares sold in this offering and (ii) to reimburse certain expenses of theplacement agent in connection with this offering. See “Plan of Distri