X0306 4 2022-12-29 0 0001816736 Disc Medicine, Inc. IRON 0001628098 Atlas Venture Fund X, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001742766 ATLAS VENTURE ASSOCIATES X, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001742765 Atlas Venture Associates X, LLC 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001759241 Atlas Venture Opportunity Fund I, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001780065 Atlas Venture Associates Opportunity I, L.P. 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 0001780066 Atlas Venture Associates Opportunity I, LLC 300 TECHNOLOGY SQUARE, 8TH FLOOR CAMBRIDGE MA 02139 0 0 1 0 Common Stock 2022-12-29 4 J 0 1835799 A 2237303 D Common Stock 2022-12-29 4 J 0 882224 A 955156 I See Footnote Gemini Therapeutics, Inc. (" Gemini"), and Disc Medicine Opco, Inc. (f/k/a Disc Medicine, Inc.) ("Disc"), entered into an Agreement and Plan of Merger and Reorganization (the "Merger Agreement"), on August 9, 2022, pursuant to which, among other matters, a direct, wholly owned subsidiary of Gemini, Gemstone Merger Sub, Inc. ("Merger Sub"), merged with and into Disc, with Disc surviving as a wholly owned subsidiary of Gemini, and the surviving corporation of the merger, which transaction is referred to herein as the merger. The merger closed on on December 29, 2022. Following the effectiveness of the merger on December 29, 2022, the surviving corporation changed its name from Gemini to Disc Medicine, Inc. (the "Issuer"). (Continued from footnote 1) Upon the closing of the merger, each share of Disc common stock (after giving effect to the conversion of each share of Disc's preferred stock into Disc common stock and including all such shares that are converted into Disc common stock) was converted into the right to receive a number of shares of Gemini common stock equal to an exchange ratio of 0.1096. These shares are held directly by Atlas Venture Fund X, L.P. ("Atlas X"). Atlas Venture Associates X, L.P. ("Associates X") is the general partner of Atlas X. Atlas Venture Associates X, LLC ("Associates X LLC") is the general partner of Associates X. Each of Associates X and Associates X LLC disclaims Section 16 beneficial ownership of the securities held by Atlas X, except to the extent of its pecuniary interest therein, if any. These shares are held directly by Atlas Venture Opportunity Fund I, L.P. ("Atlas Opportunity I"). Atlas Venture Associates Opportunity I, L.P. ("Associates I") is the general partner of Atlas Opportunity I. Atlas Venture Associates Opportunity I, LLC ("Associates I LLC") is the general partner of Associates I. Each of Associates I and Associates I LLC disclaims Section 16 beneficial ownership of the securities held by Atlas Opportunity I, except to the extent of its pecuniary interest therein, if any. Atlas Venture Fund X, L.P., By: Atlas Venture Associates X, L.P., its general partner, By: Atlas Venture Associates X, LLC, its general partner, By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2023-01-03 Atlas Venture Associates X, L.P., By: Atlas Venture Associates X, LLC, its general partner, By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2023-01-03 Atlas Venture Associates X, LLC By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2023-01-03 Atlas Venture Opportunity Fund I, L.P., By: Atlas Venture Associates Opportunity I, L.P., its general partner, By: Atlas Venture Associates Opportunity I, LLC, its general partner, By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2023-01-03 Atlas Venture Associates Opportunity I, L.P., By: Atlas Venture Associates Opportunity I, LLC, its general partner, By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2023-01-03 Atlas Venture Associates Opportunity I, LLC By: Ommer Chohan, Chief Financial Officer /s/ Ommer Chohan 2023-01-03