Director Nathan Fountain sells 6,400 Acumen (ABOS) shares at ~$2.23

Rhea-AI Filing Summary

Acumen Pharmaceuticals director Nathan B. Fountain reported an open-market sale of 6,400 shares of Common Stock. The shares were sold on June 9, 2026 at a weighted average price of about $2.23 per share. After this transaction, he directly holds 48,150 shares of Acumen common stock.

Insider Trade Summary

Net Seller: 6,400 shares ($14,273)

Net Sell 1 txn

Insider Fountain Nathan B

Role null

Sold 6,400 shs ($14K)

Type	Security	Shares	Price	Value
Sale	Common Stock	6,400	$2.2301	$14K

Holdings After Transaction: Common Stock — 48,150 shares (Direct, null)

Footnotes (1)

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Key Figures

Shares sold: 6,400 shares Weighted average sale price: $2.2301 per share Price range: $2.2300–$2.2311 per share +1 more

4 metrics

Shares sold 6,400 shares Open-market sale of Common Stock on June 9, 2026

Weighted average sale price $2.2301 per share Average price across multiple sale transactions

Price range $2.2300–$2.2311 per share Range of individual sale prices in the transaction

Shares owned after sale 48,150 shares Direct holdings following the June 9, 2026 sale

Key Terms

open-market sale, weighted average sales price, Common Stock, Form 4

4 terms

open-market sale financial

"reported selling 6,400 shares of Common Stock in an open-market transaction"

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

weighted average sales price financial

"The price reported is a weighted average sales price."

Common Stock financial

"open-market sale of 6,400 shares of Common Stock"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

Form 4 regulatory

"The sale was disclosed on Form 4 and reflects a standard insider trade"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

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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^*

Fountain Nathan B

(Last) (First) (Middle)

C/O ACUMEN PHARMACEUTICALS, INC.

1210-1220 WASHINGTON STREET, SUITE 210

(Street)

NEWTON MASSACHUSETTS 02465

(City) (State) (Zip)

UNITED STATES

(Country)

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
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/09/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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	06/09/2026		S		6,400	D	$2.2301(1)	48,150	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. The price reported is a weighted average sales price. The shares were sold in multiple transactions at prices ranging from $2.2300 to $2.2311. 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	06/10/2026
	** 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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did Acumen Pharmaceuticals (ABOS) report in this Form 4?

Acumen Pharmaceuticals director Nathan B. Fountain reported selling 6,400 shares of Common Stock in an open-market transaction. The sale was disclosed on Form 4 and reflects a standard insider trade rather than a change in corporate operations.

At what price did Nathan B. Fountain sell Acumen (ABOS) shares?

The 6,400 Acumen shares were sold at a weighted average price of $2.2301 per share. According to the filing, individual trades occurred in a narrow range between $2.2300 and $2.2311 per share during the transaction.

How many Acumen Pharmaceuticals (ABOS) shares does the director hold after the sale?

Following the reported sale, Nathan B. Fountain directly holds 48,150 shares of Acumen Pharmaceuticals Common Stock. This post-transaction holding figure comes directly from the Form 4 and shows his remaining direct equity stake.

Was the Acumen (ABOS) insider sale a single trade or multiple trades?

The sale was executed as multiple trades. The filing notes that the reported price is a weighted average and that shares were sold in numerous transactions between $2.2300 and $2.2311 per share on the transaction date.

Who is the insider involved in the latest Acumen Pharmaceuticals (ABOS) Form 4?

The insider is Nathan B. Fountain, a director of Acumen Pharmaceuticals. The Form 4 attributes the open-market sale of 6,400 Common Stock shares directly to him, with ownership listed as direct after the transaction.