SEC FORM 3

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^*

Tanini Annita

(Last)

(First)

(Middle)

C/O KEROS THERAPEUTICS, INC.

1050 WALTHAM STREET, SUITE 302

(Street)

LEXINGTON

MASSACHUSETTS

02421

(City)

(State)

(Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
08/04/2026

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

3a. Foreign Trading Symbol

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

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

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	Corp. Controller & VP, Finance

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	46,368⁽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)
1. Title of Derivative Security (Instr. 4)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	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)
Employee Stock Option (Right to Buy)	⁽²⁾	05/28/2030	Common Stock	25,000	$28.74	D
Employee Stock Option (Right to Buy)	⁽²⁾	01/09/2031	Common Stock	6,000	$70.93	D
Employee Stock Option (Right to Buy)	⁽²⁾	01/20/2032	Common Stock	7,500	$46.3	D
Employee Stock Option (Right to Buy)	⁽³⁾	02/15/2033	Common Stock	10,000	$54.38	D
Employee Stock Option (Right to Buy)	⁽⁴⁾	02/12/2034	Common Stock	14,800	$56.18	D
Employee Stock Option (Right to Buy)	⁽⁵⁾	02/23/2036	Common Stock	7,800	$15.52	D

Explanation of Responses:

1. Includes 11,940 restricted stock units ("RSUs"). Each RSU represents the contingent right to receive one share of common stock of the Issuer and shall vest (i) 4,080 RSUs on August 15, 2026, (ii) 3,960 RSUs on February 16, 2027, (iii) 975 RSUs on May 15, 2027, and (iv) 2,925 RSUs over a three-year period in twelve equal quarterly installments with the first such vesting to occur on August 15, 2027, subject to the Reporting Person's continuous service through each such vesting date.

2. Immediately exercisable.

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.

5. One-fourth (1/4th) of the shares subject to the option shall vest on February 24, 2027, and one-twelfth (1/12th) of the remaining shares subject to the option 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	08/13/2026
	** 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.
* Form 3: SEC 1473 (03-26)