X0508 4 2026-02-24 0001664710 Keros Therapeutics, Inc. KROS 0001682068 Regnante Keith C/O KEROS THERAPEUTICS, INC. 1050 WALTHAM STREET, SUITE 302 LEXINGTON MA 02421 false true false false CHIEF FINANCIAL OFFICER 0 Employee Stock Option (Right to Buy) 15.52 2026-02-24 4 A 0 60000 0 A 2036-02-23 Common Stock 60000 60000 D One-fourth (1/4th) of the shares subject to the option shall vest on February 24, 2027, and the remaining shares subject to the option shall vest in twelve substantially equal quarterly installments thereafter, subject to the Reporting Person continuing to provide service through each such date. /s/ Keith Regnante 2026-02-26