X0206 3/A 2021-06-30 2021-06-30 0 0001576885 Acumen Pharmaceuticals, Inc. ABOS 0001709418 Stalfort John A III C/O ACUMEN PHARMACEUTICALS, INC. 427 PARK STREET CHARLOTTESVILLE VA 22902 1 0 0 0 Series B Preferred Common Stock 131595 I See footnote Each share of Series B Preferred Stock will automatically convert into the same number of shares of Common Stock of the Issuer upon the closing of the Issuer's initial public offering. The Series B Preferred Stock has no expiration date. These shares were omitted from the reporting person's original Form 3. The securities are held by Gineane Holly Stalfort, as Trustee of the John A. Stalfort III 2018 Irrevocable Trust under agreement dated as of October 25, 2018. /s/ Katherine Denby, Attorney-in-Fact 2021-07-08