Acumen (ABOS) CMO logs 10b5-1 sell-to-cover stock sales

Rhea-AI Filing Summary

Acumen Pharmaceuticals Chief Medical Officer Eric Siemers reported small automatic stock sales to cover taxes related to equity vesting. On January 21, 2026, he sold 2,331 shares of common stock at a weighted average price of $1.8035, and on January 22, 2026, he sold an additional 895 shares at $1.82 per share. The filing explains these were automatic “sell to cover” transactions to satisfy tax withholding obligations from vesting restricted stock units under a Rule 10b5-1 trading plan adopted on September 3, 2024. After these sales, Siemers beneficially owned 255,371 shares of Acumen common stock directly.

Insider Trade Summary

Net Seller: 3,226 shares ($5,833)

Net Sell 2 txns

Insider Siemers Eric

Role Chief Medical Officer

Sold 3,226 shs ($6K)

Type	Security	Shares	Price	Value
Sale	Common Stock	895	$1.82	$2K
Sale	Common Stock	2,331	$1.8035	$4K

Holdings After Transaction: Common Stock — 255,371 shares (Direct)

Footnotes (1)

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 September 3, 2024. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $1.7600 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.

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^*

Siemers Eric

(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 Medical Officer

3. Date of Earliest Transaction (Month/Day/Year)
01/21/2026

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	01/21/2026		S		2,331(1)	D	$1.8035(2)	256,266	D
Common Stock	01/22/2026		S		895(1)	D	$1.82	255,371	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 September 3, 2024.

2. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $1.7600 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.

Remarks:

	/s/ Derek Meisner, Attorney-in-Fact	01/23/2026
	** 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 ABOS Chief Medical Officer Eric Siemers report?

Eric Siemers, Chief Medical Officer of Acumen Pharmaceuticals (ABOS), reported sales of 2,331 and 895 shares of common stock on January 21 and 22, 2026, respectively.

Why did Eric Siemers sell Acumen Pharmaceuticals (ABOS) shares?

The filing states the sales represent an automatic “sell to cover” to satisfy tax withholding obligations tied to vesting restricted stock units under a Rule 10b5-1 trading plan.

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

On January 21, 2026, 2,331 shares were sold at a weighted average price of $1.8035, and on January 22, 2026, 895 shares were sold at $1.82 per share.

How many ABOS shares does Eric Siemers own after these sales?

Following the reported transactions, Eric Siemers beneficially owned 255,371 shares of Acumen Pharmaceuticals common stock, held directly.

Is the weighted average sale price for the January 21, 2026 ABOS transaction detailed?

The Form 4 reports a weighted average sale price of $1.8035 for the 2,331 shares sold on January 21, 2026, with individual trades executed between $1.7600 and $1.8700.

What trading plan covered these ABOS insider sales?

The automatic sell-to-cover transactions were executed under a Rule 10b5-1 trading plan that Eric Siemers adopted on September 3, 2024.