RA Capital funds add Climb Bio (CLYM) stake with 7,111-share purchase

Rhea-AI Filing Summary

Climb Bio, Inc. (CLYM) reported an insider purchase by investment funds managed by RA Capital. On January 5, 2026, RA Capital Healthcare Fund, L.P. bought 7,111 shares of Climb Bio common stock at a weighted average price of about $3.50 per share. After this transaction, entities advised by RA Capital collectively reported 3,403,429 shares held indirectly through RA Capital Healthcare Fund, L.P., along with additional indirect holdings through Sera Medicines, LLC, RA Capital Nexus Fund, L.P., RA Capital Nexus II Fund, L.P., RA Capital Nexus III Fund, L.P., and a separately managed account. RA Capital Management, L.P., its affiliated entities, and individuals Peter Kolchinsky and Rajeev Shah may be deemed beneficial owners through their roles but disclaim beneficial ownership except to the extent of their pecuniary interest.

Insider Trade Summary

Net Buyer: 7,111 shares ($24,889)

Net Buy 6 txns

Insider RA CAPITAL MANAGEMENT, L.P., RA Capital Healthcare Fund LP, RA Capital Nexus Fund, L.P., RA Capital Nexus Fund II, L.P., RA Capital Nexus Fund III, L.P., Kolchinsky Peter, Shah Rajeev M.

Role Director, 10% Owner | Director, 10% Owner | Director | Director | Director, 10% Owner | Director, 10% Owner | Director, 10% Owner

Bought 7,111 shs ($25K)

Type	Security	Shares	Price	Value
Purchase	Common Stock	7,111	$3.50	$25K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 3,403,429 shares (Indirect, See footnotes)

Footnotes (1)

1. The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $3.495 to $3.50 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote. These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund"). RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein. These securities are held directly by Sera. These securities are held directly by the Nexus Fund. These securities are held directly by the Nexus Fund II. These securities are held directly by Nexus Fund III. These securities are held directly by the Account.

Form 4 Insider Transactions: What Each Field Means →

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

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^*

RA CAPITAL MANAGEMENT, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Climb Bio, Inc. [ CLYM ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
01/05/2026

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	01/05/2026		P		7,111	A	$3.5(1)	3,403,429	I	See footnotes(2)(3)
Common Stock								2,479,872	I	See footnotes(3)(4)
Common Stock								1,226,497	I	See footnotes(3)(5)
Common Stock								483,679	I	See footnotes(3)(6)
Common Stock								2,866,375	I	See footnotes(3)(7)
Common Stock								841,087	I	See footnotes(3)(8)

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^*

RA CAPITAL MANAGEMENT, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(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^*

RA Capital Healthcare Fund LP

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(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^*

RA Capital Nexus Fund, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Nexus Fund II, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

RA Capital Nexus Fund III, L.P.

(Last) (First) (Middle)

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(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^*

Kolchinsky Peter

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(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^*

Shah Rajeev M.

(Last) (First) (Middle)

C/O RA CAPITAL MANAGEMENT, L.P.

200 BERKELEY STREET, 18TH FLOOR

(Street)

BOSTON MA 02116

(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 price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $3.495 to $3.50 inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

2. These securities are held directly by RA Capital Healthcare Fund, L.P. (the "Fund").

3. RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the "Nexus Fund"), RA Capital Nexus II Fund, L.P. (the "Nexus Fund II"), RA Capital Nexus III Fund, L.P. (the "Nexus Fund III") and a separately managed account (the "Account"). The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC ("Sera"). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.

4. These securities are held directly by Sera.

5. These securities are held directly by the Nexus Fund.

6. These securities are held directly by the Nexus Fund II.

7. These securities are held directly by Nexus Fund III.

8. These securities are held directly by the Account.

Remarks:

Dr. Andrew Levin, a Partner and Managing Director of the Adviser, serves on the Issuer's board of directors.

	/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.	01/07/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P.	01/07/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund GP, LLC, the General Partner of RA Capital Nexus Fund, L.P.	01/07/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund II GP, LLC, the General Partner of RA Capital Nexus Fund II, L.P.	01/07/2026
	/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund III GP, LLC, the General Partner of RA Capital Nexus Fund III, L.P.	01/07/2026
	/s/ Peter Kolchinsky, individually	01/07/2026
	/s/ Rajeev Shah, individually	01/07/2026
	** 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 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 insider transaction did RA Capital report for Climb Bio (CLYM)?

Funds advised by RA Capital Management, L.P. reported buying 7,111 shares of Climb Bio common stock on January 5, 2026 at a weighted average price of about $3.50 per share.

Who actually holds the newly purchased Climb Bio shares reported in this Form 4?

The 7,111 shares of Climb Bio common stock are held directly by RA Capital Healthcare Fund, L.P., as stated in the footnotes.

How many Climb Bio (CLYM) shares do RA Capital-related entities report after this transaction?

Following the purchase, entities advised by RA Capital Management, L.P. report 3,403,429 shares of Climb Bio common stock held indirectly through RA Capital Healthcare Fund, L.P., with additional indirect holdings reported for Sera Medicines, Nexus funds, and a separately managed account.

At what prices were the Climb Bio shares purchased in this insider transaction?

The filing states the price is a weighted average, with individual trades executed at prices ranging from $3.495 to $3.50 per share.

How are Sera Medicines and the RA Capital Nexus funds involved in Climb Bio ownership?

The footnotes explain that Sera Medicines, LLC, RA Capital Nexus Fund, L.P., RA Capital Nexus II Fund, L.P., RA Capital Nexus III Fund, L.P., and a separately managed account each directly hold Climb Bio shares, with RA Capital Management, L.P. serving as investment manager.

Do Peter Kolchinsky and Rajeev Shah personally own the reported Climb Bio shares?

The filing states that RA Capital Management, L.P., its general partner, the funds, and individuals Dr. Peter Kolchinsky and Mr. Rajeev Shah may be deemed to beneficially own the securities but disclaim beneficial ownership except to the extent of their pecuniary interest.

What board representation does RA Capital have at Climb Bio (CLYM)?

The remarks note that Dr. Andrew Levin, a Partner and Managing Director of RA Capital Management, L.P., serves on Climb Bio's board of directors.