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

Rhea-AI Filing Summary

Esther Cho, SVP and General Counsel of Keros Therapeutics, Inc. (KROS), reported initial beneficial ownership on Form 3 for an event dated 08/06/2025. She directly holds 44,000 shares (RSUs) and beneficially owns employee stock options exercisable into 165,968 common shares across five option grants with exercise prices ranging from $29.02 to $70.93.

Positive

• Disclosure completeness: The Form 3 provides detailed reporting of both non-derivative RSUs and multiple derivative option grants.
• Transparent vesting terms: RSU and option vesting schedules and exercise prices are clearly stated, enabling assessment of timing and potential exercise economics.

Negative

• Potential dilution: Derivative securities cover 165,968 common shares, which could dilute existing shareholders if exercised.

Insights

Financial Analyst

TL;DR: Routine insider disclosure shows executive equity compensation concentrated in stock options and RSUs, standard for senior management.

The filing documents the initial beneficial ownership by the company’s SVP and General Counsel, combining 44,000 vested/vesting RSUs and 165,968 option-equivalent shares across grants with exercise prices from $29.02 to $70.93. The options include immediate exercisable tranches and staggered vesting schedules, indicating ongoing retention-focused compensation rather than a one-time transaction. This disclosure is procedural and provides transparency on potential future dilution.

Corporate Governance Expert

TL;DR: Governance standard filing; documents officer’s equity holdings and vesting terms to satisfy Section 16 reporting obligations.

The Form 3 fulfills Section 16(a) initial reporting requirements for a named officer. It specifies vesting schedules for RSUs and multiple option grants, with explicit vesting milestones through 2034 and some options immediately exercisable. These details allow stakeholders to assess alignment incentives and the timeline for when equity may become transferable. The disclosure itself is routine and non-eventful.

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^*

Cho Esther

(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)
	SVP, General Counsel

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	44,000(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)	05/03/2030	Common Stock	20,968	$29.02	D
Employee Stock Option (Right to Buy)	(2)	01/09/2031	Common Stock	20,000	$70.93	D
Employee Stock Option (Right to Buy)	(3)	01/20/2032	Common Stock	25,000	$46.3	D
Employee Stock Option (Right to Buy)	(4)	02/15/2033	Common Stock	50,000	$54.38	D
Employee Stock Option (Right to Buy)	(5)	02/12/2034	Common Stock	50,000	$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. Immediately exercisable.

3. One-fourth (1/4th) of the shares subject to the option vested on January 19, 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.

4. 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.

5. 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	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 did Esther Cho report on the Form 3 for KROS?

The filing reports direct ownership of 44,000 RSU shares and beneficial ownership of options exercisable into 165,968 common shares with exercise prices from $29.02 to $70.93.

When is the event date reported on the Form 3 for KROS?

The Form 3 lists the date of the event requiring the statement as 08/06/2025.

Are any of the stock options immediately exercisable for KROS filing?

Yes, the option described as Employee Stock Option (Right to Buy) with 20,968 underlying shares is noted as immediately exercisable.

What are the vesting terms for the RSUs reported by Esther Cho?

The 44,000 RSUs vest 33% on 02/17/2026, 34% on 08/15/2026, and 33% on 02/16/2027, subject to continued service.

How do the option exercise prices vary in the KROS Form 3?

Exercise prices for the reported options range from $29.02 to $70.93 across five grants.