X0306 4 2021-04-29 0001049502 MKS INSTRUMENTS INC MKSI 0001842235 Taranto Eric Robert C/O MKS INSTRUMENTS, INC. 2 TECH DRIVE, SUITE 201 ANDOVER MA 01810 1 SVP & GM, V&A Division Common Stock 2021-04-29 4 S 0 1788 185.293 D 3505.5164 D This transaction was executed in multiple trades at prices ranging from $185.27 to $185.36. 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 2021-04-30