IRON Insider Kevin Bitterman Trims Stake; Holds 1.1M Shares
Rhea-AI Filing Summary
SEC Form 4 filing (07/25/2025) discloses that Disc Medicine (IRON) director Kevin Bitterman executed two open-market sales through affiliated Atlas Venture funds.
- 07/23/2025: 29,837 common shares sold at a weighted-average price of $60.97.
- 07/24/2025: 13,033 common shares sold at a weighted-average price of $61.17.
Following the transactions, Bitterman’s indirect ownership via Atlas funds decreased from roughly 676,839 to 633,969 shares. He also continues to hold an additional 420,549 shares in Opportunity II and 51,000 shares in Atlas XII, keeping his total indirect stake above 1.1 million shares. Bitterman remains a board member and reports no derivative activity.
Positive
- None.
Negative
- Director-level insider selling of 42,870 shares at ~$61 may be viewed as profit-taking and slightly reduces perceived insider confidence.
Insights
TL;DR: Modest insider sale (~43k shares) by director; stake remains large, so impact is limited.
The sale represents about 6% of Bitterman’s previously reported indirect holdings and occurs at ~$61, near recent highs, suggesting profit-taking rather than a change in thesis. With more than 1.1 million shares still held through Atlas funds, alignment with shareholders remains substantial. No option exercises or derivative conversions accompanied the sale, indicating routine portfolio management. Given Disc Medicine’s clinical-stage profile, insider behaviour is worth monitoring, but this single filing is unlikely to materially alter valuation.
TL;DR: Transaction looks routine; no red flags on control or board commitment.
The transactions were made by venture funds, not directly by Bitterman, and are fully footnoted, maintaining transparency. Affirmations of potential pecuniary interest disclaimers align with Section 16 requirements. Bitterman remains a director and continues to hold a significant position, which preserves governance alignment. Frequency and size of future sales should be observed, but this filing alone does not signal governance concerns.
Insider Trade Summary
| Type | Security | Shares | Price | Value |
|---|---|---|---|---|
| Sale | Common Stock | 13,033 | $61.17 | $797K |
| Sale | Common Stock | 29,837 | $60.97 | $1.82M |
| holding | Common Stock | -- | -- | -- |
| holding | Common Stock | -- | -- | -- |
Footnotes (1)
- The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $60.95 to $61.10 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. These shares are held by Atlas Venture Opportunity Fund I, LP ("Opportunity I"). The general partner of Opportunity I is Atlas Venture Associates Opportunity I, LP ("Associates I"). Atlas Venture Associates Opportunity I, LLC ("Associates I LLC") is the general partner of Associates I. The Reporting Person is a member of Associates I LLC and disclaims beneficial ownership of such securities held by Opportunity I, except to the extent of his pecuniary interest therein, if any. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $60.95 to $61.55 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote. These shares are held by Atlas Venture Opportunity Fund II, LP ("Opportunity II"). The general partner of Opportunity II is Atlas Venture Associates Opportunity II, LP ("Associates II"). Atlas Venture Associates Opportunity II, LLC ("Associates II LLC") is the general partner of Associates II. The Reporting Person is a member of Associates II LLC and disclaims beneficial ownership of such securities held by Opportunity II, except to the extent of his pecuniary interest therein, if any. These shares are held by Atlas Venture Fund XII, L.P. ("Atlas XII"). The general partner of Atlas XII is Atlas Venture Associates XII, L.P. ("Associates XII"). Atlas Venture Associates XII, LLC ("Associates XII LLC") is the general partner of Associates XII. The Reporting Person is a member of Associates XII LLC and disclaims beneficial ownership of such securities held by Atlas XII, except to the extent of his pecuniary interest therein, if any.
