Acumen (NASDAQ: ABOS) legal chief sells 2,090 shares after option exercise

Rhea-AI Filing Summary

Acumen Pharmaceuticals’ Chief Legal Officer Derek M. Meisner exercised employee stock options for 2,090 shares of common stock at $1.85 per share and sold the same 2,090 shares at $3.26 per share.

These transactions were carried out automatically under a pre-arranged Rule 10b5-1 trading plan adopted on March 29, 2025. After the sale, Meisner directly holds 173,999 shares of Acumen common stock, indicating this was a relatively small, routine liquidity event.

Insider Trade Summary 10b5-1

Net Seller: 2,090 shares ($6,813)

Net Sell 3 txns

Insider Meisner Derek M

Role Chief Legal Officer & Corp Sec

Sold 2,090 shs ($7K)

Type	Security	Shares	Price	Value
Exercise	Employee Stock Option (right to buy)	2,090	$0.00	--
Exercise	Common Stock	2,090	$1.85	$4K
Sale	Common Stock	2,090	$3.26	$7K

Holdings After Transaction: Employee Stock Option (right to buy) — 71,048 shares (Direct); Common Stock — 176,089 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 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.

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)
03/06/2026

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	03/06/2026		M		2,090	A	$1.85	176,089	D
Common Stock	03/06/2026		S(1)		2,090	D	$3.26	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	03/06/2026		M			2,090	(2)	01/06/2035	Common Stock	2,090	$0	71,048	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 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.

Remarks:

	/s/ Derek Meisner	03/10/2026
	** 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 Acumen Pharmaceuticals (ABOS) report for Derek Meisner?

Derek Meisner exercised options and sold 2,090 ABOS shares. He converted employee stock options into 2,090 common shares at $1.85, then sold all 2,090 shares at $3.26 each, treating the sequence as an exercise-and-sell event.

Was the recent Acumen Pharmaceuticals (ABOS) insider sale pre-planned?

Yes, the reported ABOS share sale was pre-planned. The filing states the 2,090-share sale occurred automatically under a Rule 10b5-1 trading plan that Derek Meisner adopted on March 29, 2025, indicating the timing was scheduled in advance.

How many Acumen Pharmaceuticals (ABOS) shares does Derek Meisner hold after the transaction?

After the transaction, Derek Meisner holds 173,999 ABOS shares. The Form 4 shows his direct ownership of Acumen common stock at 173,999 shares following the 2,090-share exercise and same-day sale, suggesting the trade was small relative to his overall position.

What type of derivative security did the Acumen (ABOS) insider exercise?

He exercised an employee stock option for 2,090 ABOS shares. The option, with a $1.85 exercise price, represents a right to buy common stock and vests in 48 equal monthly installments over four years, subject to continuous service.

What does the Rule 10b5-1 plan mean for Acumen (ABOS) investors?

The Rule 10b5-1 plan makes the ABOS trade more routine. Because the 2,090-share sale followed a pre-arranged trading plan, it is characterized as scheduled portfolio management rather than a discretionary, opportunistic trade based on short-term company developments.