X0508 4 2023-11-08 0000310158 Merck & Co., Inc. MRK 0001421339 DeLuca Richard R. MERCK & CO., INC. 126 EAST LINCOLN AVENUE RAHWAY NJ 07065 1 EVP&Pres, Merck Animal Heallth 0 Common Stock 2023-11-08 4 S 0 43823 105.0286 D 111763.592 D Common Stock - 401(k) Plan 1223.3366 I By 401(k) The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $105.0000 to $105.0750, 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 October 6, 2023 in the Merck U.S. Savings Plan, a 401(k) plan. /s/ Kelly E. W. Grez as Attorney-in-Fact for Richard R. DeLuca, Jr. 2023-11-08