Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b). Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN 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 * Pontifax Management 4 G.P. (2015) Ltd. 2. Issuer Name and Ticker or Trading Symbol Keros Therapeutics, Inc. [KROS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 14 SHENKAR STREET, BEIT OFEK, 3. Date of Earliest Transaction (Month/Day/Year) 10/15/2025 (Street) HERZLIYA PITUACH, L3 46140 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock, $0.0001 par value per share 10/15/2025 S 2,284,612 D $17.75 0 I By Pontifax (Israel) IV, L.P.(1) Common Stock, $0.0001 par value per share 10/15/2025 S 1,121,045 D $17.75 0 I By Pontifax (Cayman) IV, L.P.(2) Common Stock, $0.0001 par value per share 10/15/2025 S 1,226,412 D $17.75 0 I By Pontifax (China) IV, L.P.(3) Common Stock, $0.0001 par value per share 10/15/2025 S 155,262 D $17.75 0 I By Pontifax Late Stage Fund, L.P.(4) Common Stock, $0.0001 par value per share 5,250 I By Tomer Kariv(5) Common Stock, $0.0001 par value per share 5,250 I By Ran Nussbaum(5)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Pontifax Management 4 G.P. (2015) Ltd. 14 SHENKAR STREET, BEIT OFEK HERZLIYA PITUACH, L3 46140		X
Pontifax (Israel) IV, L.P. 14 SHENKAR STREET, BEIT OFEK HERZLIYA PITUACH, L3 46140		X
Pontifax (Cayman) IV L.P. 4 SHENKAR STREET, BEIT OFEK HERZLIYA PITUACH, L3 46140		X
Pontifax (China) IV L.P. 14 SHENKAR STREET, BEIT OFEK HERZLIYA PITUACH, L3 46140		X
Pontifax Late Stage Fund L.P. 14 SHENKAR STREET BEIT OFEK HERZLIYA PITUACH, L3 46140		X
Pontifax Late Stage GP Ltd. 14 SHENKAR STREET BEIT OFEK HERZLIYA PITUACH, L3 46140		X
Kariv Tomer C/O PONTIFAX MANAGEMENT 4 GP (2015) LTD. 14 SHENKAR STREET, BEIT OFEK HERZLIYA PITUACH, L3 46140	X	X
Nussbaum Ran C/O PONTIFAX MANAGEMENT 4 GP (2015) LTD. 14 SHENKAR STREET, BEIT OFEK HERZLIYA PITUACH, L3 46140	X	X

Signatures

Pontifax Management 4 G.P. (2015) Ltd., By: /s/ Tomer Kariv, Chief Executive Officer		10/17/2025
**Signature of Reporting Person		Date
Pontifax (Israel) IV L.P., By: /s/ Tomer Kariv, Chief Executive Officer		10/17/2025
**Signature of Reporting Person		Date
Pontifax (Cayman) IV L.P., By: /s/ Tomer Kariv, Chief Executive Officer		10/17/2025
**Signature of Reporting Person		Date
Pontifax (China) IV L.P., By: /s/ Tomer Kariv, Chief Executive Officer		10/17/2025
**Signature of Reporting Person		Date
Pontifax Late Stage Fund, L.P., By: /s/ Asaf Shinar, Chief Financial Officer		10/17/2025
**Signature of Reporting Person		Date
Pontifax Late Stage GP Ltd., By: /s/ Asaf Shinar, Chief Financial Officer		10/17/2025
**Signature of Reporting Person		Date
/s/ Tomer Kariv		10/17/2025
**Signature of Reporting Person		Date
/s/ Ran Nussbaum		10/17/2025
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(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).
(1)	The securities are held by Pontifax (Israel) IV, L.P. ("Israel IV"). Pontifax Management 4 G.P. (2015) Ltd. ("Management 4") is the ultimate general partner of Israel IV. As a result, Management 4 may be deemed to share voting and dispositive power with respect to the shares held by Israel IV. Each of Tomer Kariv and Ran Nussbaum is a Managing Partner of Management 4 and, as a result, Messrs. Kariv and Nussbaum may be deemed to share voting and investment power with respect to the shares held by Israel IV. Management 4 and Messrs. Kariv and Nussbaum disclaim beneficial ownership of such shares, except to the extent of his or its pecuniary interest therein, and the inclusion of the shares in this report shall not be deemed to be an admission of beneficial ownership of the reported shares for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise.
(2)	The securities are held by Pontifax (Cayman) IV, L.P. ("Cayman IV"). Management 4 is the ultimate general partner of Cayman IV. As a result, Management 4 may be deemed to share voting and dispositive power with respect to the shares held by Cayman IV. Each of Tomer Kariv and Ran Nussbaum is a Managing Partner of Management 4 and, as a result, Messrs. Kariv and Nussbaum may be deemed to share voting and investment power with respect to the shares held by Cayman IV. Management 4 and Messrs. Kariv and Nussbaum disclaim beneficial ownership of such shares, except to the extent of his or its pecuniary interest therein, and the inclusion of the shares in this report shall not be deemed to be an admission of beneficial ownership of the reported shares for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise.
(3)	The securities are held by Pontifax (China) IV, L.P. ("China IV"). Management 4 is the ultimate general partner of China IV. As a result, Management 4 may be deemed to share voting and dispositive power with respect to the shares held by China IV. Each of Tomer Kariv and Ran Nussbaum is a Managing Partner of Management 4 and, as a result, Messrs. Kariv and Nussbaum may be deemed to share voting and investment power with respect to the shares held by China IV. Management 4 and Messrs. Kariv and Nussbaum disclaim beneficial ownership of such shares, except to the extent of his or its pecuniary interest therein, and the inclusion of the shares in this report shall not be deemed to be an admission of beneficial ownership of the reported shares for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise.
(4)	The securities are held by Pontifax Late Stage Fund, L.P. ("Late Stage"). Pontifax Late Stage GP Ltd. ("Late Stage GP") is the general partner of Late Stage and the sole shareholder of Late Stage GP is Mr. Shlomo Karako. Pursuant to the Strategic Alliance Agreement, dated August 9, 2018, between Late Stage, Israel IV, Cayman IV and China IV (collectively the, "Pontifax IV Funds"), Late Stage invests side-by-side with the Pontifax IV Funds. By virtue of the strategic relationship, Management 4 and Tomer Kariv and Ran Nussbaum may be deemed to share voting and dispositive power with respect to the shares held by Late Stage in a manner similar to the voting and investment power with respect to the shares held by each of the Pontifax IV Funds. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein, except to the extent of his or its pecuniary interest therein.
(5)	In connection with the Stock Purchase Agreement, dated October 15, 2025, by and among certain of the Reporting Persons and the Issuer and the resignations of each of Tomer Kariv and Ran Nussbaum from the Issuer's board of directors, the Issuer accelerated the vesting of the restricted stock unit awards and certain options held by Messrs. Kariv and Nussbaum that were previously reported in their respective Form 4 filings.

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