X0306 4 2021-02-10 0000310158 Merck & Co., Inc. MRK 0001820958 Williams David Michael MERCK & CO., INC. 2000 GALLOPING HILL ROAD KENILWORTH NJ 07033 1 EVP,Chief Info&Digital Officer Common Stock 2021-02-10 4 M 0 1167 75.04 A 3659.883 D Common Stock 2021-02-10 4 F 0 467 75.04 D 3192.883 D Restricted Stock Unit 2021-02-10 4 M 0 1167 0 D 2021-02-10 2023-02-10 Common Stock 1167 2335 D Holdings include shares acquired in dividend reinvestment transactions; reflects holdings as of February 10, 2021. 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 2/10/2021, 2/10/2022 and 2/10/2023. Holdings were adjusted to 2,407 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 time-based 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. /s/ Kelly E. W. Grez as Attorney-in-Fact for David Michael Williams 2022-02-11