[Form 4] Keros Therapeutics, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Keros Therapeutics (KROS) — Form 4 filing: Pontifax-affiliated funds reported open market sales of common stock on 10/15/2025 at $17.75 per share. Reported disposals include 2,284,612 shares by Pontifax (Israel) IV, L.P.; 1,121,045 by Pontifax (Cayman) IV, L.P.; 1,226,412 by Pontifax (China) IV, L.P.; and 155,262 by Pontifax Late Stage Fund, L.P. Each fund reported 0 shares beneficially owned following the transactions.

The filing lists indirect ownership through Pontifax entities and indicates that Tomer Kariv and Ran Nussbaum each reported 5,250 shares indirectly. The footnotes state that, in connection with a Stock Purchase Agreement dated October 15, 2025 and their resignations from the board, the issuer accelerated the vesting of restricted stock units and certain options previously reported for Messrs. Kariv and Nussbaum.

Insights

Equity Ownership & Governance Analyst

Large selling funds fully exited at $17.75 and two directors resigned; vesting accelerated under an agreement dated Oct 15, 2025.

The filing shows dispositions totaling 4,787,331 shares of Keros Therapeutics (KROS)$17.75 on Oct 15, 2025 by affiliated Pontifax funds: Israel IV (2,284,612), Cayman IV (1,121,045), China IV (1,226,412), and Late Stage (155,262). Each fund reports 0 shares beneficially owned following the transactions, indicating a complete exit by those entities. Two individuals each report indirect beneficial ownership of 5,250 shares, with no transaction reported for those lines.

A footnote discloses a Stock Purchase Agreement dated Oct 15, 2025 and the resignations of Tomer Kariv and Ran Nussbaum from the board. In connection with this, the issuer accelerated vesting of restricted stock units and certain options previously reported for those individuals. This links a major shareholder exit with board changes and equity award acceleration on the same date.

Key dependencies include any forthcoming disclosure detailing the Stock Purchase Agreement terms and any Form 8‑K regarding the board resignations. Items to watch: confirmation of board composition changes and any subsequent Section 16 reports around Oct–Nov 2025 that update remaining beneficial ownership.

10/17/2025 - 05:53 PM

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

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

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

X

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 for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Pontifax Management 4 G.P. (2015) Ltd.

(Last) (First) (Middle)

14 SHENKAR STREET, BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

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)

3. Date of Earliest Transaction (Month/Day/Year)
10/15/2025

4. If Amendment, Date of 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

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)

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 Securities Underlying Derivative Security (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: 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

1. Name and Address of Reporting Person^*

Pontifax Management 4 G.P. (2015) Ltd.

(Last) (First) (Middle)

14 SHENKAR STREET, BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Pontifax (Israel) IV, L.P.

(Last) (First) (Middle)

14 SHENKAR STREET, BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Pontifax (Cayman) IV L.P.

(Last) (First) (Middle)

4 SHENKAR STREET, BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Pontifax (China) IV L.P.

(Last) (First) (Middle)

14 SHENKAR STREET, BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Pontifax Late Stage Fund L.P.

(Last) (First) (Middle)

14 SHENKAR STREET

BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Pontifax Late Stage GP Ltd.

(Last) (First) (Middle)

14 SHENKAR STREET

BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Kariv Tomer

(Last) (First) (Middle)

C/O PONTIFAX MANAGEMENT 4 GP (2015) LTD.

14 SHENKAR STREET, BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Nussbaum Ran

(Last) (First) (Middle)

C/O PONTIFAX MANAGEMENT 4 GP (2015) LTD.

14 SHENKAR STREET, BEIT OFEK

(Street)

HERZLIYA PITUACH L3 46140

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

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.

	Pontifax Management 4 G.P. (2015) Ltd., By: /s/ Tomer Kariv, Chief Executive Officer	10/17/2025
	Pontifax (Israel) IV L.P., By: /s/ Tomer Kariv, Chief Executive Officer	10/17/2025
	Pontifax (Cayman) IV L.P., By: /s/ Tomer Kariv, Chief Executive Officer	10/17/2025
	Pontifax (China) IV L.P., By: /s/ Tomer Kariv, Chief Executive Officer	10/17/2025
	Pontifax Late Stage Fund, L.P., By: /s/ Asaf Shinar, Chief Financial Officer	10/17/2025
	Pontifax Late Stage GP Ltd., By: /s/ Asaf Shinar, Chief Financial Officer	10/17/2025
	/s/ Tomer Kariv	10/17/2025
	/s/ Ran Nussbaum	10/17/2025
	** 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 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).
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 Keros (KROS) insiders report on this Form 4?

Pontifax-affiliated funds reported sales of Keros common stock on 10/15/2025 at $17.75 per share and subsequently reported 0 shares beneficially owned by each fund.

How many KROS shares did each Pontifax fund sell?

Reported disposals: Israel IV 2,284,612 shares; Cayman IV 1,121,045; China IV 1,226,412; Late Stage Fund 155,262 — all at $17.75.

Did Tomer Kariv or Ran Nussbaum report holdings?

Yes. Each reported 5,250 shares indirectly, as shown in the beneficial ownership column.

Were there board changes tied to this event at KROS?

The footnotes state that Tomer Kariv and Ran Nussbaum resigned from the board on 10/15/2025 in connection with a Stock Purchase Agreement.

Were any equity awards affected for KROS insiders?

The issuer accelerated the vesting of restricted stock units and certain options held by Messrs. Kariv and Nussbaum, per the footnotes.

What ownership status was reported after the sales?

Each Pontifax fund listed above reported 0 shares beneficially owned following the transactions on 10/15/2025.