X0306 4 2022-05-03 0000310158 Merck & Co., Inc. MRK 0001854644 LeCointe-Cephas Lisa MERCK & CO., INC. 2000 GALLOPING HILL ROAD KENILWORTH NJ 07033 1 SVP Chief Ethics & Com Officer Common Stock 2022-05-04 4 M 0 813 87.10 A 3942.781 D Common Stock 2022-05-04 4 F 0 279 87.10 D 3663.781 D Stock Option (Right to Buy) 87.10 2022-05-03 4 A 0 11650 0 A 2023-05-03 2032-05-02 Common Stock 11650 11650 D Restricted Stock Unit 2022-05-03 4 A 0 2067 0 A 2023-05-03 2025-05-03 Common Stock 2067 2067 D Restricted Stock Unit 2022-05-04 4 M 0 813 0 D 2022-05-04 2024-05-04 Common Stock 813 1629 D Holdings include shares acquired in dividend reinvestment transactions. The option vests and becomes exercisable in equal installments on 5/3/2023, 5/3/2024 and 5/3/2025. Each restricted stock unit represents a contingent right to receive one share of Merck & Co., Inc. common stock. These restricted stock units vest and are distributed as shares of Merck & Co., Inc. common stock in three equal installments on 5/3/2023, 5/3/2024, and 5/3/2025. Holdings reflect the adjustments that occurred as of June 2, 2021 in connection with the Organon & Co. ("Organon") spin-off as described in the registration statement on Form 10 filed with the SEC by Organon (the "Form 10"). As reported in the Form 10, all Merck restricted stock unit awards outstanding as of immediately prior to the distribution date were converted on the distribution date into adjusted Merck awards for Merck employees to preserve the same intrinsic value and general terms and conditions (including vesting) as were in place immediately prior to the adjustments. These restricted stock units vest and are distributed as shares of Merck & Co., Inc. common stock in three equal installments on 5/4/2022, 5/4/2023 and 5/4/2024. /s/ Kelly E. W. Grez as attorney-in-fact for Lisa LeCointe-Cephas 2022-05-05