X0609 4 2026-06-12 0001049502 MKS INC MKSI 0001797189 Schreiner James Alan false C/O MKS INC. 2 TECH DRIVE ANDOVER MA 01810 1 EVP & COO 0 Common Stock 2026-06-12 4 S 0 2471 345.5239 D 20230.121 D Common Stock 2026-06-12 4 S 0 812 346.4058 D 19418.121 D Common Stock 2026-06-12 4 S 0 217 347.00 D 19201.121 D This transaction was executed in multiple trades at prices ranging from $345.000 to $345.935. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide, upon request, the full information regarding the number of shares and prices at which the transaction was effected. This transaction was executed in multiple trades at prices ranging from $346.000 to $346.795. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide, upon request, the full information regarding the number of shares and prices at which the transaction was effected. /s/ M. Kathryn Rickards, attorney-in-fact 2026-06-16