X0508 4 2024-05-03 0000310158 Merck & Co., Inc. MRK 0002003375 Smart Dalton 126 EAST LINCOLN AVENUE RAHWAY NJ 07065 1 SVP Fin. - Global Controller 0 Common Stock 2024-05-03 4 M 0 516 128.26 A 3433.286 D Common Stock 2024-05-03 4 F 0 255 128.26 D 3178.286 D Common Stock 2024-05-03 4 M 0 1530 128.26 A 4708.286 D Common Stock 2024-05-03 4 F 0 590 128.26 D 4118.286 D Common Stock 2024-05-04 4 M 0 612 127.51 A 4730.286 D Common Stock 2024-05-04 4 F 0 302 127.51 D 4428.286 D Restricted Stock Unit 2024-05-03 4 M 0 516 0 D 2024-05-03 2025-05-03 Common Stock 516 518 D Restricted Stock Unit 2024-05-03 4 M 0 1530 0 D 2024-05-03 2025-05-03 Common Stock 1530 1532 D Restricted Stock Unit 2024-05-04 4 M 0 612 0 D 2024-05-04 2024-05-04 Common Stock 612 0 D Each restricted stock unit represents a contingent right to receive one share of Merck & Co., Inc. common stock. These restricted stock units vest and are distributed as shares of Merck & Co., Inc. common stock in equal, annual installments with one installment having vested on 5/3/2024 and the last installment to vest on 5/3/2025. These restricted stock units vested and were distributed as shares of Merck & Co., Inc. common stock on 5/4/2024. /s/ Kelly E. W. Grez, attorney-in-fact for Dalton Smart 2024-05-06