Form
SCHEDULE 13D/A
Active or control-oriented beneficial ownership filing.
Atlas Venture Fund X, L.P. - 12 Dec 2025 SCHEDULE 13D/A Report for DISC MEDICINE, INC. Common Stock, $0.0001 par value per share (IRON)
- Filing manager
- Atlas Venture Fund X, L.P.
- Reporting owner
- Atlas Venture Fund X, L.P.
- Beneficially owned shares
- 813,167 shares
- Large-stake signal
-
Ownership
2.2%Beneficial ownership of this reported class.
Shares
813,167 sharesShares beneficially owned as disclosed.
Event date
12 Dec 2025Date tied to the ownership event or amendment.
Accepted by SEC
17 Dec 2025EDGAR acceptance date.
How to read this large-stake filing
- Schedule 13D/G filings focus on beneficial ownership stakes, not a full portfolio.
- Compare this filing with the holder history and issuer page before treating the percentage as a current position.
- Use amendments to understand whether the disclosed stake increased, decreased, or changed reporting status.
- Class ownership
- 2.2%
- Symbol
- IRON
- Shares outstanding
- 36,962,136 shares
- SEC form
- SCHEDULE 13D/A
- Accepted by SEC
- 17 Dec 2025, 20:07:46 UTC
- Event date
- 12 Dec 2025
- Prior SEC filing
- 15 Aug 2025
- Source filing
- View source filing
Ownership signal
CIK-linked ownership evidence from parsed SEC filings.
2 signals
Subject security
Names, identifiers, and filing context for this profile.
2 source fields
Source evidence
Original filing metadata and source links for verification.
5 source fields
Key filing fact
Atlas Venture Fund X, L.P. disclosed 2.2% ownership in DISC MEDICINE, INC. Common Stock, $0.0001 par value per share (IRON) on 12 Dec 2025.
Key facts
- Atlas Venture Fund X, L.P. filed SCHEDULE 13D/A for DISC MEDICINE, INC. Common Stock, $0.0001 par value per share (IRON).
- Disclosed ownership: 2.2%.
- Date of event: 12 Dec 2025.
Change
- Previous schedule filing date: 15 Aug 2025.
- Current filing was accepted on 17 Dec 2025, 20:07.
Research use
- This page turns one Schedule 13D/G filing into a quick large-stake read before the raw reporting-person rows.
- Use the linked SEC filing as the source of truth for ownership percentages, shares, and reporting-party details.
Evidence
Backed by Schedule 13D/13G
View source filing
Beneficial ownership values are sourced from the original SEC Schedule 13D/13G filing.
Reporting persons
Disclosed reporting parties (12)
Names, ownership percentages, voting power, signatures, titles, and CIKs as disclosed in this Schedule 13D/G filing.
| Name | Ownership | Shares owned | Sole voting power | Shared voting power | Signature | Title | CIK |
|---|---|---|---|---|---|---|---|
| Atlas Venture Fund X, L.P. | 2.2% | 813,167 | 0 | 813,167 | /s/ Ommer Chohan | By: Atlas Venture Associates X, L.P., its general partner, By: Atlas Venture Associates X, LLC, its general partner, By: Ommer Chohan, its CFO | 0001628098 |
| ATLAS VENTURE ASSOCIATES X, L.P. | 2.2% | 813,167 | 0 | 813,167 | /s/ Ommer Chohan | By: Atlas Venture Associates X, LLC, its general partner, By: Ommer Chohan, its CFO | 0001742766 |
| Atlas Venture Associates X, LLC | 2.2% | 813,167 | 0 | 813,167 | /s/ Ommer Chohan | Ommer Chohan, CFO | 0001742765 |
| Atlas Venture Fund XII, L.P. | 0% | 14,013 | 0 | 14,013 | /s/ Ommer Chohan | By: Atlas Venture Associates XII, L.P., its general partner, By: Atlas Venture Associates XII, LLC, its general partner, By: Ommer Chohan, its CFO | 0001812049 |
| Atlas Venture Associates XII, L.P. | 0% | 14,013 | 0 | 14,013 | /s/ Ommer Chohan | By: Atlas Venture Associates XII, LLC, its general partner, By: Ommer Chohan, its CFO | 0001845875 |
| Atlas Venture Associates XII, LLC | 0% | 14,013 | 0 | 14,013 | /s/ Ommer Chohan | Ommer Chohan, CFO | 0001845871 |
| Atlas Venture Opportunity Fund I, L.P. | 0.9% | 349,210 | 0 | 349,210 | /s/ Ommer Chohan | By: Atlas Venture Associates Opportunity I, L.P., its G.P., By: Atlas Venture Associates Opportunity I, LLC, its G.P., By: Ommer Chohan, CFO | 0001759241 |
| Atlas Venture Associates Opportunity I, L.P. | 0.9% | 349,210 | 0 | 349,210 | /s/ Ommer Chohan | By: Atlas Venture Associates Opportunity I, LLC, its General Partner, By: Ommer Chohan, CFO | 0001780065 |
| Atlas Venture Associates Opportunity I, LLC | 0.9% | 349,210 | 0 | 349,210 | /s/ Ommer Chohan | Ommer Chohan, CFO | 0001780066 |
| Atlas Venture Opportunity Fund II, L.P. | 0.9% | 337,485 | 0 | 337,485 | /s/ Ommer Chohan | By: Atlas Venture Associates Opportunity II, L.P., its G.P., By: Atlas Venture Associates Opportunity II, LLC, its G.P., By: Ommer Chohan, CFO | 0001885327 |
| Atlas Venture Associates Opportunity II, LP | 0.9% | 337,485 | 0 | 337,485 | /s/ Ommer Chohan | By: Atlas Venture Associates Opportunity II, LLC, its General Partner, By: Ommer Chohan, CFO | 0001935814 |
| Atlas Venture Associates Opportunity II, LLC | 0.9% | 337,485 | 0 | 337,485 | /s/ Ommer Chohan | Ommer Chohan, CFO | 0001935810 |
CIK / CUSIP context first