James B. Murray Jr. discloses 3.61M shares in Acumen Pharmaceuticals (NASDAQ: ABOS)

Rhea-AI Filing Summary

Acumen Pharmaceuticals, Inc. Schedule 13G reports that James B. Murray Jr. beneficially owned 3,611,360 shares of common stock as of April 6, 2026, representing 5.00% of outstanding common stock based on a 72,212,758 share denominator. The filing breaks ownership into 3,468,465 shares held in Mr. Murray's revocable trust and 142,895 shares held by Praxis Technologies LLC; Mr. Murray is a manager of Praxis and shares voting/dispositive power for those shares.

Insights

Governance Analyst

Beneficial position reached a 5.00% threshold; passive ownership details disclosed.

The filing states a beneficial holding of 3,611,360 shares (5.00%) as of April 6, 2026, split between a revocable trust and an LLC where Mr. Murray is a manager. Ownership percentages use specified share counts from the company’s Form 10-K denominators.

Disclosure clarifies voting and dispositive powers: sole power over 3,468,465 shares and shared power over 142,895 shares. Subsequent investor filings or amendments will show whether the position is passive or active.

Key Figures

Beneficial ownership: 3,611,360 shares Ownership percentage: 5.00% Shares in revocable trust: 3,468,465 shares +3 more

6 metrics

Beneficial ownership 3,611,360 shares Beneficially owned as of April 6, 2026

Ownership percentage 5.00% Percent of outstanding common stock using 72,212,758 share denominator (as disclosed in Form 10-K)

Shares in revocable trust 3,468,465 shares Held by James B. Murray Jr. as Trustee (part of the 3,611,360 total)

Shares held by Praxis Technologies LLC 142,895 shares Held by Praxis Technologies LLC; Mr. Murray is a manager

Prior-year beneficial ownership 3,081,057 shares Beneficially owned as of April 4, 2025 (5.01% using 60,573,425 denominator)

Form signature date 04/07/2026 Signature date on Schedule 13G

Key Terms

Beneficially owned, Sole dispositive power, Denominator, Revocable Trust

4 terms

Beneficially owned regulatory

"As of April 6, 2026, Mr. Murray beneficially owned 3,611,360 shares"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Sole dispositive power regulatory

"Sole power to dispose or to direct the disposition of: 3,468,465"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

Denominator financial

"based on the denominator of 72,212,758 shares of the Issuer's Common Stock outstanding"

The denominator is the number on the bottom of a fraction that shows the total population or base used to calculate a rate, percentage or ratio — for example, the total shares outstanding when calculating earnings per share, or all trial participants when reporting a safety rate. It matters to investors because changing the denominator (by issuing more shares, changing the population measured, or narrowing the base) can make percentages and per‑unit figures look better or worse even if the underlying raw numbers stay the same, much like changing the size of a pizza makes each slice appear larger or smaller.

Revocable Trust legal

"held by James B. Murray, Jr., as Trustee of the James B. Murray, Jr. Revocable Trust U/A/D 8/5/1991"

A revocable trust is a legal arrangement where the person who creates it keeps control and can change or cancel the trust at any time, while naming who will manage and receive the assets later. Think of it like a flexible folder for your investments and property that can be relabeled or reworked as circumstances change; it matters to investors because it determines how ownership is recorded, how easily assets transfer on incapacity or death, and whether holdings bypass public probate proceedings.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Acumen Pharmaceuticals, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

00509G209

(CUSIP Number)

04/04/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 00509G209

1

Names of Reporting Persons

James B. Murray Jr.

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 3,468,465.00
6	Shared Voting Power 142,895.00
7	Sole Dispositive Power 3,468,465.00
8	Shared Dispositive Power 142,895.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,611,360.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.00 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: This Schedule 13G is being filed late due to an inadvertent oversight.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Acumen Pharmaceuticals, Inc.
(b)	Address of issuer's principal executive offices: 1210-1220 Washington Street, Suite 210, Newton, Massachusetts 02465
Item 2.
(a)	Name of person filing: James B. Murray Jr.
(b)	Address or principal business office or, if none, residence: c/o Murray Enterprises, LLC 427 Park Street Charlottesville, VA 22902
(c)	Citizenship: United States of America
(d)	Title of class of securities: Common Stock, $0.0001 par value per share
(e)	CUSIP Number(s): 00509G209
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: As of April 6, 2026, Mr. Murray beneficially owned 3,611,360 shares of the Issuer's Common Stock, consisting of: (i) 3,468,465 shares held by James B. Murray, Jr., as Trustee of the James B. Murray, Jr. Revocable Trust U/A/D 8/5/1991 and (ii) 142,895 shares held by Praxis Technologies LLC. James B. Murray, Jr. is a manager of Praxis Technologies, LLC and has the power to vote or dispose of shares held by the entity, along with another manager of Praxis Technologies, LLC. As of April 4, 2025, Mr. Murray beneficially owned 3,081,057 shares of the Issuer's Common Stock, consisting of: (i) 2,938,162 shares held by James B. Murray, Jr., as Trustee of the James B. Murray, Jr. Revocable Trust U/A/D 8/5/1991 and (ii) 142,895 shares held by Praxis Technologies LLC.
(b)	Percent of class: Percent of Common Stock and total voting power of the Issuer's Common Stock is based on the denominator of 72,212,758 shares of the Issuer's Common Stock outstanding as of March 20, 2026, as disclosed in the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 26, 2026. Based on the above, as of April 6, 2026, Mr. Murray beneficially owned 5.00% of the Issuer's outstanding Common Stock, representing 5.00% of the total voting power of the Issuer's outstanding Common Stock. As of April 4, 2025, Mr. Murray beneficially owned 5.01% of the Issuer's outstanding Common Stock, based on the denominator of 60,573,425 shares of the Issuer's Common Stock outstanding as of March 24, 2025, as disclosed in the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission on March 27, 2025.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 3,468,465
	(ii) Shared power to vote or to direct the vote: 142,895
	(iii) Sole power to dispose or to direct the disposition of: 3,468,465
	(iv) Shared power to dispose or to direct the disposition of: 142,895
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

James B. Murray Jr.

Signature:	/s/ James B. Murray, Jr.
Name/Title:	James B. Murray, Jr.
Date:	04/07/2026

FAQ

What stake does James B. Murray Jr. hold in Acumen Pharmaceuticals (ABOS)?

He owns 3,611,360 shares, representing 5.00% of outstanding common stock. The filing states this figure as of April 6, 2026, using a 72,212,758 share denominator disclosed in the company's Annual Report on Form 10-K.

How is Mr. Murray's 3,611,360-share position composed?

3,468,465 shares are held in his revocable trust and 142,895 by Praxis Technologies LLC. The filing notes Mr. Murray is a manager of Praxis and has voting/dispositive powers over the LLC-held shares.

What voting and dispositive powers does Mr. Murray have?

Sole voting and dispositive power over 3,468,465 shares and shared voting and dispositive power over 142,895 shares. These allocations are shown explicitly in the ownership table.

What dates anchor the ownership percentages reported?

Ownership totals are reported as of April 6, 2026 and April 4, 2025. The 5.00% figure uses a March 20, 2026 denominator of 72,212,758 shares; the prior-year 5.01% uses a March 24, 2025 denominator of 60,573,425 shares.

Why was this Schedule 13G filed late?

The filing includes a comment stating it was filed late due to an inadvertent oversight. That explanation appears in the form's comment field and is signed by Mr. Murray on April 7, 2026.