Derek M. Meisner - 06 Mar 2026 Form 4 Insider Report for Acumen Pharmaceuticals, Inc. (ABOS)

Role: Chief Legal Officer & Corp Sec
Signature: /s/ Derek Meisner
Issuer symbol: ABOS
Transactions as of: 06 Mar 2026
Net transactions value: -$6,813
Form type: 4
Filing time: 10 Mar 2026, 21:45:26 UTC
Previous filing: 03 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Meisner Derek M	Chief Legal Officer & Corp Sec	C/O ACUMEN PHARMACEUTICALS, INC., 1210-1220 WASHINGTON STREET, SUITE 210, NEWTON	/s/ Derek Meisner	10 Mar 2026	0001752461

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	ABOS	Common Stock	Options Exercise		+2,090	+1.2%	$1.85^*	176,089	06 Mar 2026	Direct
transaction	ABOS	Common Stock	Sale	$6,813	-2,090	-1.2%	$3.26	173,999	06 Mar 2026	Direct	F1

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	ABOS	Employee Stock Option (right to buy)	Options Exercise		-2,090	-2.9%	$0.000000^*	71,048	06 Mar 2026	Common Stock	2,090	$1.85	Direct	F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

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).

Explanation of Responses:

Id	Content
F1	The reported sales occurred automatically pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 29, 2025.
F2	The shares subject to the option will vest in 48 equal monthly installments such that the option is fully vested on the fourth anniversary of the date of grant, subject to the Reporting Person's continuous service through each such vesting date.