[Form 3] Keros Therapeutics, Inc. Initial Statement of Beneficial Ownership

Rhea-AI Filing Summary

Keros Therapeutics insider Lorena Raquel Lerner, identified as the company’s Chief Science Officer, reports beneficial ownership of 35,000 restricted stock units and employee stock options covering 41,379 underlying shares. The RSUs vest in three tranches (33% on Feb 17, 2026; 34% on Aug 15, 2026; 33% on Feb 16, 2027). Listed options have exercise prices of $43.99, $54.38 and $56.18 with multi-year vesting schedules.

Insights

Financial Analyst

TL;DR: Routine insider equity grants and options for a senior officer; no immediate dilution or material financing effect.

The filing documents standard compensation-related equity for a named executive, comprising 35,000 RSUs with time-based vesting and employee stock options totaling 41,379 underlying shares at exercise prices of $43.99, $54.38 and $56.18. Such awards align management incentives with shareholder interests but represent typical, non-transactional disclosures that are not expected to materially affect capitalization or cash flows.

Corporate Governance Expert

TL;DR: Standard Section 16 disclosure confirming an officer’s equity holdings and vesting terms; governance signal is neutral.

The Form 3 confirms the Chief Science Officer’s direct ownership and the vesting structure for both RSUs and options, which is customary for retention and alignment. Vesting is time-based with staggered dates; there are no performance-based contingencies disclosed. From a governance perspective this is routine disclosure fulfilling reporting obligations, without evidence of related-party transactions or unusual terms.

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

Lerner Lorena Raquel

(Last) (First) (Middle)

C/O KEROS THERAPEUTICS, INC.

1050 WALTHAM STREET, SUITE 302

(Street)

LEXINGTON MA 02421

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
08/06/2025

3. Issuer Name and Ticker or Trading Symbol
Keros Therapeutics, Inc. [ KROS ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Science Officer

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	35,000(1)	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (Right to Buy)	(2)	05/14/2032	Common Stock	10,879	$43.99	D
Employee Stock Option (Right to Buy)	(3)	02/15/2033	Common Stock	7,500	$54.38	D
Employee Stock Option (Right to Buy)	(4)	02/12/2034	Common Stock	23,000	$56.18	D

Explanation of Responses:

1. 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.

2. 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.

3. 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.

4. 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.

	/s/ Esther Cho, Attorney-in-Fact	08/15/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 5 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What securities did KROS Chief Science Officer report owning on the Form 3?

The reporting person disclosed 35,000 RSUs and employee stock options covering 41,379 underlying common shares.

What is the RSU vesting schedule reported for Lorena Raquel Lerner?

The RSUs vest 33% on Feb 17, 2026, 34% on Aug 15, 2026 and 33% on Feb 16, 2027, subject to continued service.

What are the exercise prices for the reported stock options?

The options have exercise prices of $43.99, $54.38 and $56.18 as disclosed in the filing.

Are the reported holdings direct or indirect ownership?

The Form 3 indicates the reported RSUs and options are held in a direct (D) ownership form.

Do the disclosures show any related-party transactions or unusual terms?

No related-party transactions or atypical terms are disclosed; the filing presents standard equity awards and vesting schedules.