SCHEDULE 13D/A

Disc Medicine Inc

Common Stock, $0.0001 par value per share · CUSIP: 254604101

Event date: 2025-12-12

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• Atlas Venture Fund X, L.P.Reported CIK 0001628098

  Shares: 813,167.00 · Class: 2.2%

• ATLAS VENTURE ASSOCIATES X, L.P.Reported CIK 0001742766

  Shares: 813,167.00 · Class: 2.2%

• Atlas Venture Associates X, LLCReported CIK 0001742765

  Shares: 813,167.00 · Class: 2.2%

• Atlas Venture Fund XII, L.P.Reported CIK 0001812049

  Shares: 14,013.00 · Class: 0.0%

• Atlas Venture Associates XII, L.P.Reported CIK 0001845875

  Shares: 14,013.00 · Class: 0.0%

• Atlas Venture Associates XII, LLCReported CIK 0001845871

  Shares: 14,013.00 · Class: 0.0%

• Atlas Venture Opportunity Fund I, L.P.Reported CIK 0001759241

  Shares: 349,210.00 · Class: 0.9%

• Atlas Venture Associates Opportunity I, L.P.Reported CIK 0001780065

  Shares: 349,210.00 · Class: 0.9%

• Atlas Venture Associates Opportunity I, LLCReported CIK 0001780066

  Shares: 349,210.00 · Class: 0.9%

• Atlas Venture Opportunity Fund II, L.P.Reported CIK 0001885327

  Shares: 337,485.00 · Class: 0.9%

• Atlas Venture Associates Opportunity II, LPReported CIK 0001935814

  Shares: 337,485.00 · Class: 0.9%

• Atlas Venture Associates Opportunity II, LLCReported CIK 0001935810

  Shares: 337,485.00 · Class: 0.9%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.