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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(Print or Type Responses)

1. Name and Address of Reporting Person * RA CAPITAL MANAGEMENT, L.P. 2. Issuer Name and Ticker or Trading Symbol Acumen Pharmaceuticals, Inc. [ABOS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 200 BERKELEY STREET, 18TH FLOOR, 3. Date of Earliest Transaction (Month/Day/Year) 06/04/2025 (Street) BOSTON, MA 02116 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 06/04/2025 A 12,800(1) A $ 0 12,800 I See footnotes(2)(3) Common Stock 13,043,179 I See footnotes(2)(4) Common Stock 1,300,034 I See footnotes(2)(5) Common Stock 588,850 I See footnotes(2)(6)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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

Stock Option (Right to Buy)

$1.07

06/04/2025

A

19,500

(7)

06/04/2035

Common Stock

19,500

$ 0

19,500

I

See Footnotes(2)(3)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X
RA Capital Healthcare Fund LP 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X
RA Capital Nexus Fund II, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X
Kolchinsky Peter C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X
Shah Rajeev M. C/O RA CAPITAL MANAGEMENT, L.P. 200 BERKELEY STREET, 18TH FLOOR BOSTON, MA 02116	X	X

Signatures

/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.		06/05/2025
**Signature of Reporting Person		Date
/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC, the General Partner of RA Capital Healthcare Fund, L.P.		06/05/2025
**Signature of Reporting Person		Date
/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund II GP, LLC, the General Partner of RA Capital Nexus Fund II, L.P.		06/05/2025
**Signature of Reporting Person		Date
/s/ Peter Kolchinsky, individually		06/05/2025
**Signature of Reporting Person		Date
/s/ Rajeev Shah, individually		06/05/2025
**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)	Represents the grant of a restricted stock unit ("RSU") award to Laura Stoppel pursuant to the Issuer's non-employee director compensation policy. Each RSU represents a contingent right to receive one share of the Issuer's Common Stock. The RSUs will vest in full on the earlier of June 4, 2026 or the Issuer's 2026 annual stockholder meeting, subject to Dr. Stoppel's continuous service as a director through such vesting date.
(2)	RA Capital Management, L.P. (the "Adviser") is the investment manager for RA Capital Healthcare Fund, L.P. (the "Fund"), RA Capital Nexus Fund II, L.P. (the "Nexus Fund II") 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. Each of the Adviser, the Adviser GP, the Fund, the Nexus Fund II, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.
(3)	Under Dr. Stoppel's arrangement with the Adviser, Dr. Stoppel holds the RSU and the option for the benefit of the Fund and the Nexus Fund II. Dr. Stoppel is obligated to turn over to the Adviser any net cash or stock received upon exercise of the option or settlement of the RSU, as applicable, which will offset advisory fees owed by the Fund and the Nexus Fund II to the Adviser. The Reporting Persons therefore disclaim beneficial ownership of the RSU, the option and underlying common stock.
(4)	Held directly by the Fund.
(5)	Held directly by the Nexus Fund II.
(6)	Held directly by the Account.
(7)	Represents the grant of an option to Dr. Stoppel pursuant to the Issuer's non-employee director compensation policy. The shares subject to the option will vest on the earlier of June 4, 2026 or the 2026 annual stockholder meeting, subject to Dr. Stoppel's continuous service as a director through such vesting date.
Remarks: Laura Stoppel, a Principal of the Adviser, serves on the Issuer's board of directors.

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