X0508 4 2024-01-02 0 0001826457 Monte Rosa Therapeutics, Inc. GLUE 0001778843 Wallace Owen B. MONTE ROSA THERAPEUTICS, INC. 321 HARRISON AVENUE, SUITE 900 BOSTON MA 02118 0 1 0 0 Chief Scientific Officer 0 Common Stock 5266 D Stock Option (Right to Buy) 5.71 2024-01-02 4 A 0 119000 0.00 A 2034-01-01 Common Stock 119000 119000 D Includes an aggregate of 5,266 shares previously acquired under the Issuer's 2021 Employee Stock Purchase Plan. 25% of this option shall vest and become exercisable on January 1, 2025, with the remainder vesting in 36 substantially equal monthly installments thereafter, subject to the Reporting Person's continued service on each such vesting date. /s/ Markus Warmuth, Attorney-in-Fact 2024-01-04