Acumen Pharmaceuticals, Inc. Form 4 Filings

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.

Acumen Pharmaceuticals reported an equity compensation grant linked to director Dr. Laura Stoppel, as reflected on this Form 4 by RA Capital entities and related reporting persons. Dr. Stoppel received a restricted stock unit award covering 35,500 shares of common stock and a stock option for 53,250 shares with a $2.29 exercise price.

The RSUs and option will each vest in full on the earlier of the first anniversary of the grant date or the 2027 annual stockholder meeting, assuming Dr. Stoppel continues in service through that date. Under her arrangement with RA Capital Management, L.P., she holds these awards for the benefit of RA Capital Healthcare Fund, RA Capital Nexus Fund II and a separately managed account, and must deliver any net stock or cash received to the adviser to offset advisory fees. The reporting persons disclaim beneficial ownership of these awards and the underlying common stock beyond any pecuniary interest.

Acumen Pharmaceuticals director Nathan B. Fountain received new equity awards as part of his compensation. He was granted 35,500 shares of common stock in the form of restricted stock units, bringing his direct common stock holdings to 54,550 shares after the award. He also received stock options for 53,250 shares with an exercise price of $2.29 per share. Both the RSUs and options vest in full on the earlier of the first anniversary of the grant date or the 2027 annual stockholder meeting, provided he continues serving the company through that date.

Acumen Pharmaceuticals director Kimberlee C. Drapkin received new equity awards. She was granted 35,500 restricted stock units, each representing a right to receive one share of common stock. These RSUs vest in full on the earlier of the first anniversary of the grant date or the 2027 annual stockholder meeting, subject to continued service.

She also received stock options covering 53,250 shares at an exercise price of $2.29 per share, expiring on June 3, 2036, with the same vesting schedule. Following these awards, she directly holds 48,300 shares of Acumen common stock. The transactions reflect compensation-related grants rather than open-market purchases or sales.

Acumen Pharmaceuticals director John A. Stalfort III received new equity awards. On June 3, 2026, he was granted 35,500 restricted stock units, each representing one share of common stock, and 53,250 stock options with an exercise price of $2.29 per share.

The RSUs and the option grant will vest in full on the earlier of the first anniversary of the grant date or the 2027 annual stockholder meeting, as long as he continues to serve through that date. Following these awards, he directly holds 220,624 shares of common stock.

Acumen Pharmaceuticals director Derrell Porter received new equity awards. He was granted 35,500 restricted stock units, each representing one share of common stock, which will vest in full on the earlier of the first anniversary of the grant date or the 2027 annual stockholder meeting, subject to his continuous service.

Porter was also granted stock options for 53,250 shares of common stock at an exercise price of $2.29 per share, expiring on June 3, 2036, with the same vesting schedule. Following these grants, he directly holds 48,300 shares of common stock.

Acumen Pharmaceuticals director Jeffrey L. Ives received new equity awards as part of his compensation. He was granted 35,500 restricted stock units, each convertible into one share of common stock, and a stock option covering 53,250 shares at an exercise price of $2.29 per share.

The RSUs and the option will vest in full on the earlier of the first anniversary of the June 3, 2026 grant date or the company’s 2027 annual stockholder meeting, as long as he remains in continuous service. After the RSU grant, he directly holds 48,300 shares of common stock.

Acumen Pharmaceuticals director George Golumbeski received new equity compensation awards. He was granted 35,500 restricted stock units, each representing one share of common stock, and a stock option covering 53,250 shares at an exercise price of $2.29 per share.

The RSUs and the option will vest in full on the earlier of the first anniversary of the grant date or the 2027 annual stockholder meeting, subject to his continuous service. After these grants, he directly holds 35,500 shares of common stock and 53,250 stock options from this award.

Stoppel Laura reported acquisition or exercise transactions in this Form 4 filing.

Acumen Pharmaceuticals director Laura Stoppel reported equity awards tied to RA Capital-managed vehicles. She was granted 35,500 restricted stock units (RSUs), each representing one share of common stock, and 53,250 stock options with a strike price of $2.29 per share.

The RSUs and options vest in full on the earlier of the first anniversary of the June 3, 2026 grant date or the 2027 annual stockholder meeting, subject to her continuous service. Under her arrangement with RA Capital Management, L.P., any shares or cash from these awards benefit RA Capital Healthcare Fund, RA Capital Nexus Fund II and a separately managed account, and she disclaims beneficial ownership of the underlying stock.

Acumen Pharmaceuticals, Inc. reported that investment entities associated with RA Capital Management, L.P. acquired 6,060,606 shares of common stock at $3.30 per share in a grant or award transaction on March 16, 2026. The shares are held indirectly, including by RA Capital Healthcare Fund, L.P., with 19,103,785 shares reported as held following the transaction. Additional indirect holdings include 1,300,034 shares held by RA Capital Nexus Fund II, L.P. and 588,850 shares held in a separately managed account. The Adviser entities and managing members disclaim beneficial ownership beyond their respective pecuniary interests.

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.

Acumen Pharmaceuticals Chief Legal Officer Derek M. Meisner exercised employee stock options for 9,406 shares of common stock at a price of $1.85 per share and immediately sold 9,406 common shares in an open-market transaction at a weighted average price of $3.0099 per share. These sales occurred automatically under a Rule 10b5-1 trading plan adopted on March 29, 2025.

After these transactions, Meisner directly owned 173,999 shares of common stock and held 73,138 shares underlying employee stock options. The options vest in 48 equal monthly installments from the grant date, subject to continuous service.

Acumen Pharmaceuticals Chief Legal Officer Derek Meisner reported option exercises and related stock sales. On January 26 and 28, 2026, he exercised a total of 17,756 employee stock options at an exercise price of $1.85 per share, acquiring the same number of common shares.

On those same dates, he sold 17,756 common shares at weighted average prices of $3.0005 and $3.0016 per share under a pre-established Rule 10b5-1 trading plan. Following these transactions, he directly owned 173,999 common shares and retained vested and unvested stock options that vest in 48 equal monthly installments from the grant date.

Acumen Pharmaceuticals Chief Legal Officer Derek M. Meisner reported three sales of common stock under pre-arranged Rule 10b5-1 trading plans. On January 21, 2026, he sold 2,247 shares at a weighted average price of $1.8083 per share through an automatic “sell to cover” transaction to satisfy tax withholding tied to vesting restricted stock units under a plan adopted on May 15, 2024. On January 22, 2026, he sold 1,054 shares at $1.84 per share, and on January 23, 2026, he sold 5,633 shares at a weighted average price of $1.9027 per share under a separate Rule 10b5-1 plan adopted on March 29, 2025. After these transactions, he directly owned 173,999 shares of Acumen Pharmaceuticals common stock.

Acumen Pharmaceuticals Chief Medical Officer Eric Siemers reported small automatic stock sales to cover taxes related to equity vesting. On January 21, 2026, he sold 2,331 shares of common stock at a weighted average price of $1.8035, and on January 22, 2026, he sold an additional 895 shares at $1.82 per share. The filing explains these were automatic “sell to cover” transactions to satisfy tax withholding obligations from vesting restricted stock units under a Rule 10b5-1 trading plan adopted on September 3, 2024. After these sales, Siemers beneficially owned 255,371 shares of Acumen common stock directly.

Acumen Pharmaceuticals insider activity: CFO & Chief Business Officer Matt Zuga reported small automatic stock sales tied to tax withholding. On 01/21/2026, he sold 2,473 shares of common stock at a weighted average price of $1.8072 per share, followed by a sale of 1,687 shares at $1.86 per share on 01/22/2026. These transactions were executed as “sell to cover” trades to satisfy tax obligations from vesting restricted stock units under a Rule 10b5-1 trading plan adopted on August 30, 2024. After these sales, he directly beneficially owns 304,924 shares of Acumen common stock.

Acumen Pharmaceuticals, Inc. Chief Executive Officer Daniel Joseph O'Connell reported automatic stock sales related to tax withholding. On January 21, 2026, he sold 9,346 shares of common stock at a weighted average price of $1.8112 per share. On January 22, 2026, he sold an additional 2,689 shares at a weighted average price of $1.8838 per share.

According to the footnotes, these transactions were automatic "sell to cover" trades to satisfy tax withholding obligations arising from the vesting of restricted stock units under a Rule 10b5-1 trading plan adopted on June 24, 2024. After these sales, O'Connell beneficially owned 881,275 shares of Acumen common stock directly.

Acumen Pharmaceuticals Chief Operating Officer Barton Russell reported automatic sales of company common stock to cover taxes on vested restricted stock units. On January 21, 2026, he sold 2,315 shares at a weighted average price of $1.806 per share, and on January 22, 2026, he sold an additional 462 shares at $1.84 per share. These transactions were executed as "sell to cover" trades under a Rule 10b5-1 trading plan that he adopted on August 30, 2024, specifically to satisfy tax withholding obligations related to RSU vesting.

Following these transactions, Russell directly held 205,092 shares of Acumen Pharmaceuticals common stock.

Acumen Pharmaceuticals Chief Executive Officer and director Daniel Joseph O’Connell reported new equity awards in the form of restricted stock units and stock options. On January 20, 2026, he received 299,800 shares of Common Stock as a restricted stock unit (RSU) award at a price of $0, increasing his directly held Common Stock to 893,310 shares after the transaction. Each RSU represents the right to receive one share of Acumen’s Common Stock and will vest in three equal annual installments starting one year after the grant date, contingent on his continued service.

On the same date, O’Connell was also granted an employee stock option covering 450,000 shares of Common Stock at an exercise price of $1.86 per share. These options were awarded at no upfront cost and will vest in 48 equal monthly installments so that they are fully vested on the fourth anniversary of the grant date, again subject to his continuous service. Following this grant, he holds 450,000 stock options directly.

Acumen Pharmaceuticals reported that its CFO and Chief Business Officer, Matt Zuga, received new equity awards. On 01/16/2026, he was granted 99,133 shares of Common Stock as a restricted stock unit (RSU) award at a price of $0 per share, increasing his directly held Common Stock to 309,084 shares.

On the same date, he also received an Employee Stock Option to buy 148,700 shares of Common Stock at an exercise price of $1.89 per share, with 148,700 derivative securities held directly after the grant. The RSUs vest in three equal annual installments starting one year after the grant date, while the stock options vest in 48 equal monthly installments and become fully vested on the fourth anniversary of the grant date, in each case contingent on his continuous service.

Acumen Pharmaceuticals’ Chief Legal Officer Derek M. Meisner reported new equity awards in the company. On January 16, 2026, he received 99,133 shares of Common Stock as a restricted stock unit (RSU) award at a price of $0 per share, bringing his directly owned Common Stock to 182,933 shares. Each RSU represents a right to receive one share of Common Stock and will vest in three equal annual installments starting one year after the grant date, as long as he continues in service.

He also received an employee stock option to buy 148,700 shares of Common Stock at an exercise price of $1.89 per share, with no cost reported for the grant itself. These options vest in 48 equal monthly installments and are fully vested on the fourth anniversary of the grant date, subject to his continuous service, and expire on January 16, 2036.

Acumen Pharmaceuticals Chief Medical Officer Eric Siemers reported new equity awards from the company. On January 16, 2026, he received 99,133 shares of Common Stock at a price of $0, described as a restricted stock unit award that vests in three equal annual installments starting one year after the grant date, subject to continued service. The filing also shows a grant of an employee stock option for 148,700 shares of Common Stock at an exercise price of $1.89 per share, vesting in 48 equal monthly installments and expiring on January 16, 2036. Following these grants, Siemers directly owns 258,597 shares of Common Stock and 148,700 stock options.

Acumen Pharmaceuticals Chief Operating Officer Barton Russell reported new equity awards in the company. On 01/16/2026, he received 84,600 shares of Common Stock in the form of restricted stock units, granted at a price of $0. These RSUs vest in three equal annual installments starting one year after the grant date, as long as he continues in service.

On the same date, he was also granted an employee stock option for 126,900 shares of Common Stock with an exercise price of $1.89 per share. The option vests in 48 equal monthly installments and is fully vested on the fourth anniversary of the grant date, subject to continued service. After these transactions, Russell directly beneficially owned 207,869 shares of Common Stock and 126,900 stock options.

Acumen Pharmaceuticals Chief Regulatory Officer Amy Schacterle reported new equity awards. On January 16, 2026, she received 84,600 shares of Common Stock as a restricted stock unit award at a reported price of $0 per share, bringing her directly held Common Stock to 92,303 shares. The RSUs vest in three equal annual installments starting one year after the grant date, as long as she remains in continuous service.

She was also granted an employee stock option for 126,900 shares of Common Stock with an exercise price of $1.89 per share. This option vests in 48 equal monthly installments so that it is fully vested on the fourth anniversary of the grant date, subject to her continued service, and she held 126,900 options following the transaction.

Acumen Pharmaceuticals reported that its President and Chief Development Officer, James J. Doherty, received new equity awards. On January 16, 2026, he was granted 166,867 restricted stock units (RSUs) of common stock at no cost, increasing his directly held common shares to 220,900. Each RSU represents the right to receive one share of common stock and will vest in three equal annual installments starting one year after the grant date, as long as he remains in continuous service.

On the same date, Doherty also received an employee stock option covering 250,300 shares of common stock with an exercise price of $1.89 per share. These options were granted at no upfront cost and will vest in 48 equal monthly installments so that the option is fully vested on the fourth anniversary of the grant date, subject to his continued service with the company.

Acumen Pharmaceuticals CFO & Chief Business Officer Matt Zuga reported a small insider sale of company common stock. On January 8, 2026, he sold 6,888 shares at a weighted average price of $1.8166 per share, with individual trades executed between $1.72 and $1.95.

According to the disclosure, these shares were sold through an automatic “sell to cover” transaction to satisfy tax withholding obligations triggered by the vesting of restricted stock units. The transaction was made under a Rule 10b5-1 trading plan adopted on June 30, 2025. After this activity, Zuga beneficially owned 209,951 shares of Acumen Pharmaceuticals common stock.

Acumen Pharmaceuticals, Inc. reported an insider stock sale by its Chief Operating Officer, Barton Russell. On January 8, 2026, he sold 3,530 shares of common stock in a transaction coded as a sale. The filing explains this was an automatic “sell to cover” to satisfy tax withholding obligations tied to the vesting of restricted stock units under a Rule 10b5-1 trading plan he adopted on June 25, 2025. The shares were sold at a weighted average price of $1.8588 per share, in multiple trades between $1.8000 and $1.9500. After this transaction, he continued to beneficially own 123,269 shares, all held directly.

Acumen Pharmaceuticals Chief Legal Officer Derek Meisner reported several sales of Acumen common stock under a pre-arranged Rule 10b5-1 trading plan. On January 8, 2026, he sold 6,819 shares at a weighted average price of $1.8154 in an automatic “sell to cover” transaction to satisfy tax withholding on vesting restricted stock units, and 30,092 shares at a weighted average price of $1.8233 under the same plan.

He later sold 5,200 shares on January 9, 2026 at a weighted average price of $1.7633, and 8,548 shares on January 12, 2026 at a weighted average price of $1.7148. After these transactions, Meisner directly held 83,800 shares of Acumen common stock.

Acumen Pharmaceuticals Chief Executive Officer and director Daniel Joseph O’Connell reported automatic share sales tied to tax withholding. On January 8, 9 and 12, 2026, he sold 8,143, 12,941 and 5,388 shares of Acumen Pharmaceuticals common stock, respectively, at weighted average prices of $1.8194, $1.7643 and $1.7273 per share.

According to the footnotes, these transactions represent automatic “sell to cover” trades to satisfy tax withholding obligations upon vesting of restricted stock units, pursuant to a Rule 10b5-1 trading plan adopted on June 27, 2025. After these sales, O’Connell beneficially owned 593,510 shares of common stock directly.

Acumen Pharmaceuticals officer James J. Doherty reported automatic sales of company stock to cover taxes tied to restricted stock unit vesting. On January 7, 2026, he sold 1,700 shares of common stock at a weighted average price of $1.9879, and on January 8, 2026 he sold 6,467 shares at a weighted average price of $1.8198, in each case through a Rule 10b5-1 trading plan.

The filing states that these were “sell to cover” transactions to satisfy tax withholding obligations and that Doherty held 54,033 shares of common stock directly after the second sale. It also notes that the reported beneficial ownership reflects a correction of a typographical error in a prior Form 4 that had overreported an RSU grant to Doherty by 400 shares.

Acumen Pharmaceuticals' Chief Regulatory Officer, Amy Schacterle, reported an automatic sale of company stock tied to tax withholding. On 01/07/2026, she sold 1,097 shares of Acumen common stock at a weighted average price of $1.9838 per share. The shares were sold under a pre-arranged Rule 10b5-1 trading plan and were executed as a “sell to cover” transaction to satisfy tax withholding obligations from the vesting of restricted stock units.

After this transaction, Schacterle beneficially owns 7,703 shares of Acumen common stock. A Rule 10b5-1 plan allows insiders to schedule trades in advance, which can help separate routine tax-related or liquidity transactions from discretionary trading decisions.

Acumen Pharmaceuticals, Inc. executive stock activity: CFO & Chief Business Officer Matt Zuga reported several sales of Acumen common stock. On January 5, 2026, he sold 4,000 shares at a weighted average price of $1.9606. On January 6, 2026, he sold 5,100 shares at a weighted average price of $1.9662. On January 7, 2026, he sold 4,105 shares at a weighted average price of $1.995 and an additional 1,700 shares at a weighted average price of $1.9862. Footnotes explain that the 4,000- and 1,700-share sales were automatic “sell to cover” transactions to satisfy tax withholding on vesting RSUs under Rule 10b5-1 trading plans adopted on August 30, 2024 and June 30, 2025. After these transactions, he beneficially owned 216,839 shares of Acumen common stock directly.

Acumen Pharmaceuticals Chief Medical Officer Eric Siemers reported automatic sales of company common stock to cover taxes on vesting restricted stock units. On January 5, 2026, he sold 4,000 shares at a weighted average price of $1.9587, and on January 6, 2026, he sold 6,834 shares at a weighted average price of $1.967.

The filing states these transactions were "sell to cover" sales executed under a Rule 10b5-1 trading plan adopted on September 3, 2024, to satisfy tax withholding obligations from RSU vesting. After these sales, Siemers beneficially owned 159,464 shares of Acumen Pharmaceuticals common stock in direct ownership.

Acumen Pharmaceuticals, Inc. chief executive Daniel Joseph O’Connell reported automatic sales of company common stock to cover taxes on equity awards. On January 5, 6, and 7, 2026, he sold 4,649, 5,102, and 37,755 shares of Acumen common stock, respectively, at weighted average prices of $1.971, $1.9662, and $1.986 per share. The filing states these were sell-to-cover transactions to satisfy tax withholding obligations tied to the vesting of restricted stock units under a Rule 10b5-1 trading plan adopted on June 24, 2024. Following the latest reported sale, O’Connell beneficially owned 619,982 shares of Acumen common stock directly.

Acumen Pharmaceuticals Chief Legal Officer and Corporate Secretary Derek Meisner reported several sales of common stock in early January 2026. On January 5 and 6, he sold blocks of shares, including 4,000 shares at $1.9595 and 7,097 shares at $1.9672 per share. Some of these transactions were automatic “sell to cover” sales to pay tax withholding tied to vesting restricted stock units under a Rule 10b5-1 trading plan adopted in May 2024.

Additional sales on January 6 and 7 were made under a separate Rule 10b5-1 trading plan adopted in March 2025, with prices such as $1.9670, $1.9876 and $1.9896 per share. After the reported transactions, Meisner directly beneficially owned 134,459 shares of Acumen Pharmaceuticals common stock.

Acumen Pharmaceuticals Chief Operating Officer Barton Russell reported routine insider share sales linked to equity compensation. Over January 5–7, 2026, he sold a total of 9,318 shares of Acumen common stock in three transactions at weighted average prices of $1.9581, $1.9664, and $1.9871.

The footnotes state these were automatic “sell to cover” trades to satisfy tax withholding obligations upon vesting of restricted stock units under Rule 10b5-1 trading plans adopted on August 30, 2024 and June 25, 2025. After these sales, Russell beneficially owned 126,799 shares of Acumen common stock directly.

Acumen Pharmaceuticals (ABOS) reported a Form 4 showing a director received a stock option grant for 50,000 shares on 11/06/2025 at an exercise price of $1.9 per share. The option expires 11/06/2035.

The award vests in equal monthly installments over three years, becoming fully vested on the third anniversary of the grant date, and will become immediately exercisable prior to the effectiveness of a change in control. Following the reported transaction, 50,000 derivative securities were beneficially owned, held directly.