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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13D/A 0001104659-25-034310 0001940272 XXXXXXXX LIVE 4 Common Stock, $0.0001 par value per share 08/21/2025 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 5389264.00 0.00 5389264.00 0.00 5389264.00 Y 13.27 OO The amounts reported in boxes 7, 9 and 11 include (i) 4,391,237 shares of Common Stock held by ADAR1 Partners, LP, (ii) 743,358 shares of Common Stock held by Spearhead Insurance Solutions IDF, LLC and (iii) 254,669 shares of Common Stock held by ADAR1 SPV I, LP as of August 21, 2025. As the investment manager of ADAR1 Partners, LP and ADAR1 SPV I, LP and as the sub-advisor of Spearhead Insurance Solutions IDF, LLC, ADAR1 Capital Management, LLC may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP, ADAR1 SPV I, LP and Spearhead Insurance Solutions IDF, LLC. Amounts reported do not include shares underlying certain swap arrangements as disclosed in the Schedule 13D. The percentage in box 13 is based on 40,615,414 shares of Common Stock of the Issuer outstanding as of July 31, 2025, reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025, filed with the SEC on August 6, 2025. Y ADAR1 Capital Management GP, LLC b AF N TX 4645906.00 0.00 4645906.00 0.00 4645906.00 Y 11.44 OO The amounts reported in boxes 7, 9 and 11 include (i) 4,391,237 shares of Common Stock held by ADAR1 Partners, LP and (ii) 254,669 shares of Common Stock held by ADAR1 SPV I, LP as of August 21, 2025. As the general partner of ADAR1 Partners, LP and ADAR1 SPV I, LP, ADAR1 Capital Management GP, LLC may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP and ADAR1 SPV I, LP. Amounts reported do not include shares underlying certain swap arrangements as disclosed in the Schedule 13D. The percentage in box 13 is based on 40,615,414 shares of Common Stock of the Issuer outstanding as of July 31, 2025, reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025, filed with the SEC on August 6, 2025. Y Daniel Schneeberger b AF N TX 5389264.00 0.00 5389264.00 0.00 5389264.00 Y 13.27 IN The amounts reported in boxes 7, 9 and 11 include (i) 4,391,237 shares of Common Stock held by ADAR1 Partners, LP, (ii) 743,358 shares of Common Stock held by Spearhead Insurance Solutions IDF, LLC and (iii) 254,669 shares of Common Stock held by ADAR1 SPV I, LP as of August 21, 2025. As the manager of ADAR1 Capital Management, LLC and ADAR1 Capital Management GP, LLC, Mr. Schneeberger may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP, Spearhead Insurance Solutions IDF, LLC, and ADAR1 SPV I, LP. Amounts reported do not include shares underlying certain swap arrangements as disclosed in the Schedule 13D. The percentage in box 13 is based on 40,615,414 shares of Common Stock of the Issuer outstanding as of July 31, 2025, reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025, filed with the SEC on August 6, 2025. Common Stock, $0.0001 par value per share Keros Therapeutics, Inc. 1050 Waltham Street, Suite 302 Lexington MA 02421 This Amendment No. 4 ("Amendment No. 4") 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. 4 have the meanings set forth in the Schedule 13D. On August 21, 2025, ADAR1 Capital Management issued a press release (the "August 21 Press Release"), including an open letter, expressing its disappointment with the Board's refusal to engage with ADAR1 Capital Management on the Issuer's strategy, capital allocation priorities and Board refreshment, and stating that it will seek to elect new directors at the next annual meeting of the Issuer's stockholders should the Board continue to refuse ADAR1 Capital Management's invitation to engage. The foregoing description of the August 21 Press Release does not purport to be complete and is qualified in its entirety by reference to the full text of the August 21 Press Release, which is attached hereto as Exhibit H and is incorporated herein by reference. The information contained on the cover pages of this Amendment No. 4 is incorporated herein by reference. The information contained on the cover pages of this Amendment No. 4 is incorporated herein by reference. No transactions in the shares of Common Stock have been effected by the Reporting Persons during the past sixty (60) days. The Reporting Persons no longer hold the Long Puts and Short Puts previously reported in the Schedule 13D. Exhibit H: August 21 Press Release ADAR1 Capital Management, LLC /s/ Daniel Schneeberger Daniel Schneeberger, Manager 08/21/2025 ADAR1 Capital Management GP, LLC /s/ Daniel Schneeberger Daniel Schneeberger, Manager 08/21/2025 Daniel Schneeberger /s/ Daniel Schneeberger Daniel Schneeberger 08/21/2025