Acumen (NASDAQ: ABOS) CLO exercises options and sells 9,406 shares

Rhea-AI Filing Summary

Acumen Pharmaceuticals Chief Legal Officer Derek M. Meisner exercised employee stock options for 9,406 shares of common stock at a price of $1.85 per share and immediately sold 9,406 common shares in an open-market transaction at a weighted average price of $3.0099 per share. These sales occurred automatically under a Rule 10b5-1 trading plan adopted on March 29, 2025.

After these transactions, Meisner directly owned 173,999 shares of common stock and held 73,138 shares underlying employee stock options. The options vest in 48 equal monthly installments from the grant date, subject to continuous service.

Insider Trade Summary

Net Seller: 9,406 shares ($28,311)

Net Sell 3 txns

Insider Meisner Derek M

Role Chief Legal Officer & Corp Sec

Sold 9,406 shs ($28K)

Type	Security	Shares	Price	Value
Exercise	Employee Stock Option (right to buy)	9,406	$0.00	--
Exercise	Common Stock	9,406	$1.85	$17K
Sale	Common Stock	9,406	$3.0099	$28K

Holdings After Transaction: Employee Stock Option (right to buy) — 73,138 shares (Direct); Common Stock — 183,405 shares (Direct)

Footnotes (1)

1. The reported sales occurred automatically pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 29, 2025. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $3.0000 to $3.0300. 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. The shares subject to the employee stock option vest in 48 equal monthly installments starting on the date the option was granted, such that the option will be fully vested on the fourth anniversary of the date of grant, subject to the Reporting Person's continuous service through each such vesting date.

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).

X

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^*

Meisner Derek M

(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 Legal Officer & Corp Sec

3. Date of Earliest Transaction (Month/Day/Year)
02/27/2026

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	02/27/2026		M		9,406	A	$1.85	183,405	D
Common Stock	02/27/2026		S(1)		9,406	D	$3.0099(2)	173,999	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
Employee Stock Option (right to buy)	$1.85	02/27/2026		M			9,406	(3)	01/06/2035	Common Stock	9,406	$0	73,138	D

Explanation of Responses:

1. The reported sales occurred automatically pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 29, 2025.

2. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $3.0000 to $3.0300. 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 shares subject to the employee stock option vest in 48 equal monthly installments starting on the date the option was granted, such that the option will be fully vested on the fourth anniversary of the date of grant, subject to the Reporting Person's continuous service through each such vesting date.

Remarks:

	/s/ Derek Meisner	03/03/2026
	** 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 transactions did ABOS executive Derek Meisner report on this Form 4?

Derek Meisner reported exercising options and selling shares. He exercised employee stock options for 9,406 shares at $1.85, then sold 9,406 common shares at a weighted average price of $3.0099, all on the same date.

Was the ABOS insider stock sale by Derek Meisner part of a 10b5-1 trading plan?

Yes, the reported sales occurred under a Rule 10b5-1 plan. The filing states the transactions were executed automatically according to a trading plan Meisner adopted on March 29, 2025, providing pre-set instructions for selling shares.

How many Acumen Pharmaceuticals (ABOS) shares does Derek Meisner own after the Form 4 transactions?

After these transactions, Meisner directly held 173,999 common shares. He also held 73,138 shares underlying employee stock options, reflecting his remaining equity position following the exercise and sale reported.

What prices were involved in Derek Meisner’s ABOS option exercise and share sale?

The options were exercised at $1.85 and shares sold near $3.01. Meisner exercised options for 9,406 shares at $1.85 per share and sold 9,406 common shares at a weighted average price of $3.0099, within a $3.00 to $3.03 range.

How do Derek Meisner’s ABOS employee stock options vest over time?

The employee stock options vest in 48 equal monthly installments. Vesting begins on the grant date, and the options become fully vested on the fourth anniversary, provided Meisner remains in continuous service through each monthly vesting date.

What is the nature of the derivative transaction reported by ABOS insider Derek Meisner?

The derivative transaction reflects an option exercise into common stock. Meisner exercised an employee stock option for 9,406 shares, converting it into common stock before selling an equal number of common shares in the market.