X0508 4 2023-12-12 0 0001816736 Disc Medicine, Inc. IRON 0001591747 Bitterman Kevin C/O DISC MEDICINE, INC. 321 ARSENAL STREET, SUITE 101 WATERTOWN MA 02472 1 0 0 0 0 Common Stock 2023-12-12 4 S 0 20823 59.87 D 861401 I See footnote Common Stock 2023-12-12 4 S 0 422 60.99 D 860979 I See footnote Common Stock 2023-12-12 4 S 0 4155 62.42 D 856824 I See footnote Common Stock 2023-12-12 4 S 0 665 62.90 D 856159 I See footnote Common Stock 2023-12-12 4 S 0 688 63.78 D 855471 I See footnote Common Stock 2023-12-12 4 S 0 18615 65.10 D 836856 I See footnote Common Stock 2023-12-12 4 S 0 6599 65.77 D 830257 I See footnote Common Stock 2023-12-13 4 S 0 3508 59.99 D 826749 I See footnote Common Stock 2023-12-13 4 S 0 40 60.50 D 826709 I See footnote Common Stock 2023-12-14 4 S 0 20429 58.27 D 806280 I See footnote Common Stock 2023-12-14 4 S 0 120 59.74 D 806160 I See footnote Common Stock 218326 I See footnote Common Stock 51000 I See footnote The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $59.50 to $60.497 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 ranges set forth in footnotes (1), (3), (4), (5), (6), (7), (8), (9), (10) and (11). These shares are held by Atlas Venture Opportunity 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 $60.51 to $61.50 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $61.5297 to $62.5175 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $62.6436 to $63.3256 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $63.70 to $64.67 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $64.7499 to $65.735 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $65.745 to $66.32 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $59.50 to $60.4381 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $58.25 to $58.65 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $59.53 to $60.17 inclusive. These shares are held by Atlas Venture Opportunity 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. /s/ Ommer Chohan, Attorney-in-Fact 2023-12-14