X0306 4 2020-05-01 0000310158 Merck & Co., Inc. MRK 0001421339 DeLuca Richard R. MERCK & CO., INC. 2000 GALLOPING HILL ROAD KENILWORTH NJ 07033 1 EVP&Pres, Merck Animal Heallth Common Stock 87525.616 D Common Stock - 401(k) Plan 1103.701 I By 401(k) Stock Option (Right to Buy) 77.67 2020-05-01 4 A 0 75514 0 A 2021-05-01 2030-04-30 Common Stock 75514 75514 D Holdings include shares acquired in dividend reinvestment transactions. Includes shares acquired and dividends earned through April 7, 2020, in the Merck U.S. Savings Plan, a 401(k) plan. The option vests and becomes exercisable in three equal installments on 5/1/2021, 5/1/2022 and 5/1/2023. /s/ Faye C. Brown as Attorney-in-Fact for Richard R. DeLuca, Jr. 2020-05-05