X0206 3/A 2022-07-01 2022-07-08 0 0000310158 Merck & Co., Inc. MRK 0001722753 Guindo Chirfi MERCK & CO., INC. 126 EAST LINCOLN AVENUE RAHWAY NJ 07065 1 Chief Marketing Officer Common Stock 1399.055 D Common Stock-401(k) Plan 50.7902 I By 401(k) This Form 3/A is being filed to amend the Form 3, filed on 07/08/2022 on behalf of the Reporting Person, solely to restate the number of shares beneficially owned (direct) under Column 2 of Table I. Holdings include shares acquired in dividend reinvestment transactions. Power of Attorney has been previously filed. /s/ Kelly E. W. Grez, as attorney-in-fact for Chirfi Guindo 2023-04-28