Acumen (NASDAQ: ABOS) CEO O’Connell sells shares under 10b5-1 plan

Rhea-AI Filing Summary

Acumen Pharmaceuticals Chief Executive Officer and director Daniel Joseph O’Connell reported automatic share sales tied to tax withholding. On January 8, 9 and 12, 2026, he sold 8,143, 12,941 and 5,388 shares of Acumen Pharmaceuticals common stock, respectively, at weighted average prices of $1.8194, $1.7643 and $1.7273 per share.

According to the footnotes, these transactions represent automatic “sell to cover” trades to satisfy tax withholding obligations upon vesting of restricted stock units, pursuant to a Rule 10b5-1 trading plan adopted on June 27, 2025. After these sales, O’Connell beneficially owned 593,510 shares of 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

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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^*

OConnell Daniel Joseph

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
01/08/2026

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	01/08/2026		S		8,143(1)	D	$1.8194(2)	611,839	D
Common Stock	01/09/2026		S		12,941(1)	D	$1.7643(3)	598,898	D
Common Stock	01/12/2026		S		5,388(1)	D	$1.7273(4)	593,510	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 pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 27, 2025.

2. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $1.7200 to $1.8700. 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 $1.7100 to $1.8100. 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. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $1.6700 to $1.8400. 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	01/12/2026
	** 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 did Acumen Pharmaceuticals (ABOS) CEO Daniel O’Connell report on this Form 4?

The Form 4 reports that Chief Executive Officer and director Daniel Joseph O’Connell sold shares of Acumen Pharmaceuticals common stock in several transactions and now beneficially owns 593,510 shares directly.

How many Acumen (ABOS) shares did the CEO sell and on which dates?

Daniel O’Connell sold 8,143 shares on January 8, 2026, 12,941 shares on January 9, 2026, and 5,388 shares on January 12, 2026.

What prices were received for the Acumen (ABOS) CEO’s share sales?

The reported weighted average sale prices were $1.8194 per share on January 8, $1.7643 per share on January 9, and $1.7273 per share on January 12, 2026.

Why were Daniel O’Connell’s Acumen (ABOS) shares sold according to the filing?

A footnote states the sales represent an automatic “sell to cover” transaction to satisfy tax withholding obligations in connection with vesting of restricted stock units under a Rule 10b5-1 trading plan.

What is the Rule 10b5-1 trading plan mentioned in the Acumen (ABOS) Form 4?

The filing explains the shares were sold pursuant to a Rule 10b5-1 trading plan, described as a contract, instruction or written plan for trading equity securities intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

When was the Acumen (ABOS) CEO’s 10b5-1 plan adopted?

The footnote states that the Rule 10b5-1 trading plan under which the shares were sold was adopted by the reporting person on June 27, 2025.