Acumen Pharmaceuticals (ABOS) COO discloses Rule 10b5-1 tax sales

Rhea-AI Filing Summary

Acumen Pharmaceuticals Chief Operating Officer Barton Russell reported routine insider share sales linked to equity compensation. Over January 5–7, 2026, he sold a total of 9,318 shares of Acumen common stock in three transactions at weighted average prices of $1.9581, $1.9664, and $1.9871.

The footnotes state these were automatic “sell to cover” trades to satisfy tax withholding obligations upon vesting of restricted stock units under Rule 10b5-1 trading plans adopted on August 30, 2024 and June 25, 2025. After these sales, Russell beneficially owned 126,799 shares of Acumen common stock directly.

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
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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^*

Barton Russell

(Last) (First) (Middle)

C/O ACUMEN PHARMACEUTICALS, INC.

1210-1220 WASHINGTON STREET, SUITE 210

(Street)

NEWTON MA 02465

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Acumen Pharmaceuticals, Inc. [ ABOS ]

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

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

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)

X	Form filed by One Reporting Person
	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		S		4,000(1)	D	$1.9581(2)	132,117	D
Common Stock	01/06/2026		S		3,618(1)	D	$1.9664(3)	128,499	D
Common Stock	01/07/2026		S		1,700(4)	D	$1.9871(5)	126,799	D

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

Explanation of Responses:

1. Represents the number of shares sold by the Reporting Person through an automatic "sell to cover" transaction to satisfy tax withholding obligations in connection with the vesting of restricted stock units ("RSUs") pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on August 30, 2024.

2. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $1.9100 to $1.9800. Upon request, the Reporting Person will provide to the staff of the Securities and Exchange Commission, the Issuer, or any security holder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

3. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $1.9400 to $1.9900. Upon request, the Reporting Person will provide to the staff of the Securities and Exchange Commission, the Issuer, or any security holder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

4. Represents the number of shares sold by the Reporting Person through an automatic "sell to cover" transaction to satisfy tax withholding obligations in connection with the vesting of RSUs pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 25, 2025.

5. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $1.9550 to $2.0200. Upon request, the Reporting Person will provide to the staff of the Securities and Exchange Commission, the Issuer, or any security holder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Remarks:

	/s/ Derek Meisner, Attorney-in-Fact	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 does Acumen Pharmaceuticals (ABOS) Form 4 disclose?

The Form 4 discloses that Chief Operating Officer Barton Russell sold shares of Acumen Pharmaceuticals common stock in early January 2026, in connection with equity compensation tax withholding.

How many Acumen (ABOS) shares did COO Barton Russell sell?

Barton Russell sold 9,318 shares of Acumen common stock in three transactions: 4,000 shares on January 5, 3,618 shares on January 6, and 1,700 shares on January 7, 2026.

At what prices were the Acumen (ABOS) shares sold in this Form 4?

The reported weighted average sale prices were $1.9581 on January 5, $1.9664 on January 6, and $1.9871 on January 7, 2026, with actual trades occurring within stated price ranges around those levels.

Why did Acumen COO Barton Russell sell shares according to the Form 4?

The footnotes state the sales represent automatic “sell to cover” transactions used to satisfy tax withholding obligations when restricted stock units vested, executed under Rule 10b5-1 trading plans.

What are Rule 10b5-1 trading plans mentioned in the Acumen (ABOS) filing?

Rule 10b5-1 trading plans allow insiders to pre-arrange trades of company stock according to set instructions, which can help manage trades while reducing concerns about trading on nonpublic information.

How many Acumen (ABOS) shares does Barton Russell hold after these sales?

Following the reported transactions, Barton Russell beneficially owned 126,799 shares of Acumen Pharmaceuticals common stock directly.

Is the Acumen (ABOS) Form 4 transaction a direct or indirect holding?

The Form 4 shows the holdings as direct ownership (D) by Barton Russell, with no separate entity listed as the beneficial owner.