Form 4: Disc Medicine Director Sells Over 182K Shares

Disc Medicine Director Kevin Bitterman reported the sale of over 182,000 shares of common stock, including an option exercise and subsequent sale, in mid-December 2025.

Summary

• Director Kevin Bitterman reported multiple transactions involving Disc Medicine, Inc. common stock between December 12 and December 16, 2025, made pursuant to a Rule 10b5-1(c) plan.
• On December 15, 2025, Bitterman exercised 7,000 fully vested stock options at an exercise price of $13.50 per share.
• Immediately after exercising the options, Bitterman sold all 7,000 shares acquired at a weighted average price of $91.87 per share, resulting in zero direct beneficial ownership.
• Entities affiliated with Atlas Venture (Atlas Venture Opportunity Fund I, LP, Atlas Venture Opportunity Fund II, LP, and Atlas Venture Fund XII, L.P.), where Bitterman is a member of the respective general partner LLCs, collectively sold 175,123 shares of common stock.
• These indirect sales occurred across several transactions on December 12, 15, and 16, 2025, at weighted average prices ranging from $91.00 to $94.255 per share.
• Bitterman disclaims beneficial ownership of the shares held by the Atlas Venture funds, except to the extent of his pecuniary interest.
• Following these transactions, the Atlas Venture funds collectively hold 701,462 shares (349,603 from Opportunity I, 337,698 from Opportunity II, and 14,161 from Atlas XII).

Sentiment

Score: 4

Explanation: The sentiment is slightly negative due to significant insider selling by a director (over 182,000 shares). While the transactions were made pursuant to a Rule 10b5-1(c) plan, indicating they were pre-scheduled and not necessarily a reaction to new negative information, the substantial volume of sales by a director can still be perceived by the market as a signal of reduced conviction or a move towards diversification.

Positives

• The exercise of stock options at a significantly lower price ($13.50) compared to the sale price (weighted average $91.87) indicates a substantial profit for the insider on those specific shares.

Negatives

• Significant insider selling (over 182,000 shares) by a director, even if indirect through affiliated funds and part of a pre-arranged plan, can be perceived negatively by the market as it might suggest a lack of confidence or a move to diversify.

Future Outlook

NA

Industry Context

NA

Related Party Transactions

• The sales of common stock were conducted by Atlas Venture Opportunity Fund I, LP, Atlas Venture Opportunity Fund II, LP, and Atlas Venture Fund XII, L.P., entities where the reporting person, Kevin Bitterman, is a member of the respective general partner LLCs. Bitterman disclaims beneficial ownership except to the extent of his pecuniary interest.

Stakeholder Impact

• Shareholders: May view significant insider selling as a potential negative signal regarding the company's future prospects or valuation, potentially leading to downward pressure on the stock price.

Key Dates

Keywords

Disc Medicine, IRON, Form 4, Insider Selling, Director Stock Sale, Stock Option Exercise, Atlas Venture, Beneficial Ownership, Rule 10b5-1