Lorena Raquel Lerner - Aug 6, 2025 Form 3 Insider Report for Keros Therapeutics, Inc. (KROS)

Role: Chief Science Officer
Signature: /s/ Esther Cho, Attorney-in-Fact
Stock symbol: KROS
Transactions as of: Aug 6, 2025
Transactions value $: $0
Form type: 3
Date filed: 8/15/2025, 04:34 PM
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Lerner Lorena Raquel	Chief Science Officer	C/O KEROS THERAPEUTICS, INC., 1050 WALTHAM STREET, SUITE 302, LEXINGTON	/s/ Esther Cho, Attorney-in-Fact	2025-08-15	0002081359

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
holding	KROS	Common Stock						35K	Aug 6, 2025	Direct	F1

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
holding	KROS	Employee Stock Option (Right to Buy)							Aug 6, 2025	Common Stock	10.9K	$43.99	Direct	F2
holding	KROS	Employee Stock Option (Right to Buy)							Aug 6, 2025	Common Stock	7.5K	$54.38	Direct	F3
holding	KROS	Employee Stock Option (Right to Buy)							Aug 6, 2025	Common Stock	23K	$56.18	Direct	F4

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	Represents a restricted stock unit ("RSU") award. The RSUs vest as follows: 33% of the RSUs shall vest on February 17, 2026, an additional 34% of the total number of RSUs shall vest on August 15, 2026, and the remaining 33% of the total number of RSUs shall vest on February 16, 2027, in each case, subject to the Reporting Person continuing to provide service through each such date.
F2	One-fourth (1/4th) of the shares subject to the option vested on May 9, 2023, and one-twelfth (1/12th) of the remaining shares subject to the option vested or shall vest in equal quarterly installments thereafter, subject to the Reporting Person continuing to provide service through each such date.
F3	One-fourth (1/4th) of the shares subject to the option vested on February 16, 2024, and one-twelfth (1/12th) of the remaining shares subject to the option vested or shall vest in equal quarterly installments thereafter, subject to the Reporting Person continuing to provide service through each such date.
F4	One-fourth (1/4th) of the shares subject to the option vested on February 13, 2025, and one-twelfth (1/12th) of the remaining shares subject to the option vested or shall vest in equal quarterly installments thereafter, subject to the Reporting Person continuing to provide service through each such date.