X0306 4 2021-06-28 0 0001826457 Monte Rosa Therapeutics, Inc. GLUE 0001354345 Bolzon Bradley J PhD MONTE ROSA THERAPEUTICS, INC. 645 SUMMER STREET, SUITE 102 BOSTON MA 02210 1 0 1 0 Common Stock 2021-06-28 4 C 0 6515869 A 6799115 I By Versant Venture Capital VI, L.P. Common Stock 2021-06-28 4 C 0 1940043 A 1940043 I By Versant Vantage I, L.P. Common Stock 2021-06-28 4 P 0 157895 19.00 A 2097938 I By Versant Vantage I, L.P. Series A convertible preferred stock 2021-06-28 4 C 0 20004280 D Common Stock 5666131 0 I By Versant Capital VI, L.P. Series B convertible preferred stock 2021-06-28 4 C 0 3000000 D Common Stock 849738 0 I By Versant Capital VI, L.P. Series B convertible preferred stock 2021-06-28 4 C 0 4150000 D Common Stock 1175470 0 I By Versant Vantage I, L.P. Series C convertible preferred stock 2021-06-28 4 C 0 2699328 D Common Stock 764573 0 I By Versant Vantage I, L.P. Each share of Series A convertible preferred stock, Series B convertible preferred stock and Series C convertible preferred stock (collectively, the "Preferred Stock") was convertible at any time at the holder's election and automatically upon the closing of the Issuer's initial public offering. The Preferred Stock converted into Common Stock on a 3.5305-for-one basis upon the closing of the Issuer's initial public offering without payment or additional consideration. The Preferred Stock had no expiration date. Shares held by Versant Venture Capital VI, L.P. ("Versant VI"). Versant Ventures VI GP, L.P. ("Versant Ventures VI GP") is the general partner of Versant VI, and Versant Ventures VI GP-GP, LLC ("Versant Ventures VI GP-GP") is the general partner of Versant Ventures VI GP. The Reporting Person is a managing member of Versant Ventures VI GP-GP and may be deemed to share voting and dispositive power over the shares held by Versant VI. The Reporting Person disclaims beneficial ownership of such securities, except to the extent of his pecuniary interest therein, if any. Shares held by Versant Vantage I, L.P. ("Versant Vantage I"). Versant Vantage I GP, L.P. ("Versant Vantage I GP") is the general partner of Versant Vantage I, and Versant Vantage I GP-GP, LLC ("Versant Vantage I GP-GP") is the general partner of Versant Vantage I GP. The Reporting Person is a managing member of Versant Vantage I GP-GP, and may be deemed to share voting and dispositive power over the shares held by Versant Vantage I. The Reporting Person disclaims beneficial ownership of such securities, except to the extent of his pecuniary interest therein, if any. /s/ Ajim Tamboli, Attorney-in-Fact 2021-06-30