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Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
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SCHEDULE 13D/A 0001104659-25-034310 0001940272 XXXXXXXX LIVE 5 Common Stock, $0.0001 par value per share 10/15/2025 false 0001664710 492327101 Keros Therapeutics, Inc. 1050 Waltham Street, Suite 302 Lexington MA 02421 Daniel Schneeberger (512) 254-3790 3503 Wild Cherry Drive, Building 9 Austin TX 78738 0001940272 N ADAR1 Capital Management, LLC b AF N TX 0.00 0.00 0.00 0.00 0.00 Y 0 OO 0001940267 N ADAR1 Capital Management GP, LLC b AF N TX 0.00 0.00 0.00 0.00 0.00 Y 0 OO 0001861120 N Daniel Schneeberger b AF N TX 0.00 0.00 0.00 0.00 0.00 Y 0 IN Common Stock, $0.0001 par value per share Keros Therapeutics, Inc. 1050 Waltham Street, Suite 302 Lexington MA 02421 This Amendment No. 5 ("Amendment No. 5") amends and supplements the statement on Schedule 13D filed with the Securities and Exchange Commission on April 11, 2025 (as amended from time to time, the "Schedule 13D"). Except as otherwise stated, the Schedule 13D remains unchanged. Capitalized terms used herein and not otherwise defined in this Amendment No. 5 have the meanings set forth in the Schedule 13D. Item 4 of the Schedule 13D is hereby amended and supplemented by the addition of the following: On October 15, 2025, ADAR 1 Partners, LP, ADAR1 SPV I, LP and Spearhead Insurance Solutions IDF, LLC (the "ADAR1 Funds") and ADAR1 Capital Management (together with the ADAR1 Funds, the "ADAR1 Parties") entered into a stock purchase agreement (the "Stock Purchase Agreement") with the Issuer pursuant to which the ADAR1 Funds agreed to sell a total of 5,389,264 shares of Common Stock to the Issuer at a price equal to $17.75 per share, for an aggregate price of $95,659,436. The Stock Purchase Agreement also includes certain standstill provisions during the Standstill Period (as defined in the Stock Purchase Agreement), including, among other things, a restriction on the ability of the ADAR1 Parties to acquire an ownership interest of more than 4.9% of the outstanding shares of Common Stock. The foregoing description of the Stock Purchase Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Stock Purchase Agreement, the form of which is attached hereto as Exhibit I and is incorporated herein by reference. Items 5(a)-(c) and (e) of the Schedule 13D are hereby amended and restated as follows: (a) The information contained on the cover pages of this Amendment No. 5 is incorporated herein by reference. (b) The information contained on the cover pages of this Amendment No. 5 is incorporated herein by reference. (c) Other than as described in Item 4 of this Amendment No. 5, no transactions in the shares of Common Stock have been effected by the Reporting Persons during the past sixty (60) days. (e) October 15, 2025. Item 6 of the Schedule 13D is hereby amended and supplemented by the addition of the following: Item 4 of this Amendment No. 5 is incorporated herein by reference. Exhibit I: Stock Purchase Agreement, dated October 15, 2025. ADAR1 Capital Management, LLC /s/ Daniel Schneeberger Daniel Schneeberger, Manager 10/15/2025 ADAR1 Capital Management GP, LLC /s/ Daniel Schneeberger Daniel Schneeberger, Manager 10/15/2025 Daniel Schneeberger /s/ Daniel Schneeberger Daniel Schneeberger 10/15/2025