144 0001759241 XXXXXXXX LIVE 0001816736 Disc Medicine, Inc. 001-39438 321 ARSENAL STREET SUITE 101 WATERTOWN MA 02472 617-674-9274 Atlas Venture Opportunity Fund I, L.P. Shareholder Common Stock Merrill Lynch

One Bryant Park New York NY 10036

18039 1249741.9 34765581 10/07/2025 Nasdaq Common Stock 05/01/2020 Private Placement Issuer N 18039 05/01/2020 Cash N Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/18/2025 664 40588.79 Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/23/2025 29837 1819239.47 Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/24/2025 13033 797188.21 Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/30/2025 8492 518329.6 Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/05/2025 395 24075.25 Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/13/2025 24962 1526501.19 Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/14/2025 7212 439848.34 Atlas Venture Opportunity Fund I, LP.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/22/2025 2287 139584.07 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/18/2025 1184 72375.2 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/23/2025 53215 3244656.91 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/24/2025 23245 1421824.59 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 07/30/2025 15146 924472.46 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/05/2025 705 42969.75 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/13/2025 44520 2722531.56 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/14/2025 12862 784432.8 Atlas Venture Fund X, L.P.

300 Technology Sq Ste 8 Cambridge MA 02139

Common Stock 08/22/2025 4080 249017.5 10/07/2025 Ommer Chohan