X0609 4 2026-08-05 0000310158 Merck & Co., Inc. MRK 0002126478 Maraldo David R. false 126 EAST LINCOLN AVENUE RAHWAY NJ 07065 1 EVP & Pres. MMD 0 Common Stock 2026-08-05 4 M 0 6311 73.73 A 24523.434 D Common Stock 2026-08-05 4 S 0 6311 128.7179 D 18212.434 D Common Stock 2026-08-05 4 M 0 9709 87.10 A 27921.434 D Common Stock 2026-08-05 4 S 0 9709 128.7179 D 18212.434 D Common Stock 2026-08-05 4 M 0 2686 84.71 A 20898.434 D Common Stock 2026-08-05 4 S 0 2686 128.7179 D 18212.434 D Stock Option (Right to Buy) 73.73 2026-08-05 4 M 0 6311 0 D 2022-05-04 2031-05-03 Common Stock 6311 3154 D Stock Option (Right to Buy) 87.10 2026-08-05 4 M 0 9709 0 D 2023-05-03 2032-05-02 Common Stock 9709 0 D Stock Option (Right to Buy) 84.71 2026-08-05 4 M 0 2686 0 D 2026-04-29 2035-04-28 Common Stock 2686 5374 D The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $128.6400 to $128.8500, 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 the footnote. The option vested and became exercisable in three equal installments on 5/4/2022, 5/4/2023, and 5/4/2024. The option vested and become exercisable in three equal installments on 5/3/2023, 5/3/2024, and 5/3/2025. The options vest and become exercisable in three equal installments on 4/29/2026, 4/29/2027, and 4/29/2028. /s/ Kelly E. W. Grez as Attorney-in-Fact for David R. Maraldo 2026-08-07