X0202 SCHEDULE 13G 0001008670 XXXXXXXX LIVE Common Stock, $0.0001 par value per share 04/04/2025 0001576885 Acumen Pharmaceuticals, Inc. 00509G209 1210-1220 Washington Street Suite 210 Newton MA 02465 Rule 13d-1(c) James B. Murray Jr. X1 3468465 142895 3468465 142895 3611360 5.00 IN This Schedule 13G is being filed late due to an inadvertent oversight. Acumen Pharmaceuticals, Inc. 1210-1220 Washington Street, Suite 210, Newton, Massachusetts 02465 James B. Murray Jr. c/o Murray Enterprises, LLC 427 Park Street Charlottesville, VA 22902 United States of America Y 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. 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. 3,468,465 142,895 3,468,465 142,895 Y Y Y Y Y N 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. James B. Murray Jr. /s/ James B. Murray, Jr. 04/07/2026