Star Equity Holdings Inc美股招股说明书(2026-05-18版)

Up to $8,700,000 10% Series A Cumulative Perpetual Preferred Stock We have entered into an At Market Issuance Sales Agreement with Ladenburg Thalmann& Co. Inc. (“Ladenburg”), dated as of May18, 2026 (the “Sales Agreement”), relating to the sale ofour10% Series A Cumulative Perpetual Preferred Stock, par value $0.001 per share (“Series A Preferred Stock”), offered by this Prospectus Supplement. Ladenburg is referred to herein as the“Sales Agent.” In accordance with the terms of the Sales Agreement, under this Prospectus Supplement, we may offer and sell shares of our Series A Preferred Stock from time to time havingan aggregate offering price of up to $8,700,000 through the Sales Agent. Sales of our Series A Preferred Stock, if any, under this Prospectus Supplement will be made by any method permittedthat is deemed an “at the market offering” as defined in Rule 415 under the Securities Act of 1933, as amended (the “Securities Act”). The Sales Agent is not required to sell any specificamount but will act as our agent using commercially reasonable efforts consistent with its normal trading and sales practices. There is no arrangement for funds to be received in escrow, trustor similar arrangement. We currently have 2,369,782 shares of Series A Preferred Stock issued and outstanding. Holders of shares of the Series A Preferred Stock are entitled to receive, when and as authorized by theBoard of Directors (or a duly authorized committee thereof) and declared by the Company, out of funds legally available for the payment of dividends, preferential cumulative cash dividendsat the rate of 10.0% per annum of the $10.00 liquidation preference per share (equivalent to a fixed annual amount of $1.00 per share). Dividends on the Series A Preferred Stock shall becumulative from (but excluding) the date of original issue and shall be payable quarterly in arrears on or before the last day of each of March, June, September and December (each, a“Dividend Payment Date”) or, if such date is not a Business Day (as defined below), on the immediately succeeding Business Day or on such later date as designated by the Board ofDirectors, with the same force and effect as if paid on such date. Any dividend payable on the Series A Preferred Stock for any partial dividend period will be computed on the basis of a360-day year consisting of twelve 30-day months. Dividends will be payable to holders of record as they appear in the Company’s stock records for the Series A Preferred Stock at the close ofbusiness on the applicable record date, which shall be the first day of each of March, June, September and December, whether or not a Business Day, in which the applicable DividendPayment Date falls (each, a “Dividend Record Date”). The term “Business Day” shall mean any calendar day on which the Nasdaq Global Select Market is open for trading. Except under limited circumstances as described in this Prospectus Supplement, holders of the Series A Preferred Stock generally do not have any voting rights. Our Series A Preferred Stock is listed on the Nasdaq Global Select Market under the trading symbol “STRRP.” Sales of our Series A Preferred Stock, if any, under this prospectus supplement will be made in sales deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated underthe Securities Act of 1933, as amended (the “Securities Act”). The Sales Agent is not required to sell any specific number or dollar amount of securities, but will use commercially reasonableefforts to sell on our behalf all of the shares of Series A Preferred Stock requested to be sold by us, consistent with its normal trading and sales practices, on mutually agreed terms between theSales Agent and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement. The Sales Agent will be entitled to compensation at a commission rate of up to 3.0% of the gross sales price of Series A Preferred Stock sold under the Sales Agreement. We have also agreedto reimburse the Sales Agent for the reasonable fees and disbursements of its counsel. In connection with the sale of the Series A Preferred Stock on our behalf, the Sales Agent may bedeemed to be an “underwriter” within the meaning of the Securities Act and the compensation of the Sales Agent may be deemed to be underwriting commissions or discounts. We have alsoagreed to provide indemnification and contribution to the Sales Agent with respect to certain liabilities, including liabilities under the Securities Act or the Securities Exchange Act of 1934, asamended (the “Exchange Act”). See “Plan of Distribution” beginning on pageS-25 for additional information regarding the compensation to be paid to the Sales Agent. You should read this Prospectus Supplement in conjunction with the accompanying Base Prospectus, dated April1, 2026 (“Base Prospectus”), including any supplements and amendmentsthereto. This Prospectus Supplement is qualified by reference to the accompanying