X0306 4 2021-05-10 0000310158 Merck & Co., Inc. MRK 0001763963 Clyburn Frank MERCK & CO., INC. 2000 GALLOPING HILL ROAD KENILWORTH NJ 07033 1 EVP & Pres ? Human Health Common Stock 2021-05-10 4 M 0 19324 0 A 113672.057 D Common Stock 2021-05-10 4 S 0 19324 78.3192 D 94348.057 D Common Stock - 401(k) Plan 1753.3913 I By 401(k) Stock Option (Right to Buy) 44.98 2021-05-10 4 M 0 19324 0 D 2014-05-06 2023-05-05 Common Stock 19324 19323 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $78.27 to $78.42, inclusive. The reporting person undertakes to provide to Merck & Co., Inc., any security holder of Merck & Co., Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above in this footnote. Holdings include shares acquired in dividend reinvestment transactions. Includes shares acquired and dividends earned through April 7, 2021 in the Merck U.S. Savings Plan, a 401(k) plan. The option became exercisable in equal installments on 5/6/2014, 5/6/2015 and 5/6/2016. /s/ Kelly E. W. Grez as Attorney-in-Fact for Frank Clyburn 2021-05-11