Form 4: Former 10% Owner Sells Werewolf Therapeutics Shares

MPM BioVentures 2014, a former 10% owner of Werewolf Therapeutics, Inc., reported the sale of nearly 200,000 common shares over three days in December 2025.

Summary

• MPM BioVentures 2014, L.P., along with related entities, identified as a former 10% owner of Werewolf Therapeutics, Inc. (HOWL), reported multiple sales of common stock.
• The transactions were executed pursuant to a Rule 10b5-1 plan established on September 24, 2025.
• On December 2, 2025, 59,277 common shares were sold at a weighted average price of $0.89 per share, leaving 4,924,566 shares beneficially owned.
• On December 3, 2025, an additional 57,225 common shares were sold at a weighted average price of $0.87 per share, reducing beneficial ownership to 4,867,341 shares.
• On December 4, 2025, 83,230 common shares were sold at a weighted average price of $0.97 per share, resulting in 4,784,111 shares beneficially owned.
• In total, 199,732 common shares were disposed of across these three days.
• The sales were conducted by various entities under the MPM BioVentures umbrella, including MPM Asset Management LLC, MPM BioVentures 2014, L.P., MPM BioVentures 2014(B), L.P., MPM Asset Management Investors BV2014 LLC, MPM Oncology Innovations Fund, L.P., and UBS Oncology Impact Fund L.P.

Sentiment

Score: 3

Explanation: The sale of a substantial number of shares by a former 10% owner, even under a pre-established 10b5-1 plan, typically indicates a reduction in conviction or a strategic exit, which is generally viewed negatively by the market.

Negatives

• A former 10% owner, MPM BioVentures 2014, L.P., significantly reduced its stake in Werewolf Therapeutics, Inc. by selling 199,732 common shares over three consecutive days.
• The sales occurred at weighted average prices ranging from $0.87 to $0.97, which are relatively low, potentially indicating a lack of strong conviction in the company's near-term stock performance from a former major investor.

Risks

• The continued selling by a former significant institutional investor could exert downward pressure on the stock price.
• A reduction in ownership by a major investor might be perceived by the market as a signal of reduced confidence in the company's future prospects or valuation.

Future Outlook

NA

Industry Context

NA

Stakeholder Impact

• Shareholders may perceive these sales as a negative signal, potentially leading to downward pressure on the stock price.
• The reduction in ownership by a significant institutional investor could also impact institutional interest and liquidity for the company's stock.

Key Dates

Recommendation

The consistent selling of shares by a former 10% owner, MPM BioVentures 2014, L.P., over multiple days, even if pre-planned under a 10b5-1, suggests a strategic reduction in exposure or a lack of strong conviction in the company's near-term prospects. This insider selling activity, particularly from a significant institutional investor, typically signals potential headwinds or a perceived overvaluation, warranting a 'sell' recommendation for investors to consider reducing their holdings.

Keywords

Werewolf Therapeutics, HOWL, SEC Form 4, Insider Selling, MPM BioVentures, Stock Sale, 10b5-1 Plan, Biotechnology, Former 10% Owner