X0306 4 2022-02-15 0001049502 MKS INSTRUMENTS INC MKSI 0001414656 Lee John Tseng-Chung C/O MKS INSTRUMENTS, INC. 2 TECH DRIVE, SUITE 201 ANDOVER MA 01810 1 1 President & CEO Common Stock 2022-02-15 4 M 0 3065.722 A 37223.4 D Common Stock 2022-02-15 4 M 0 2754.821 A 39978.221 D Common Stock 2022-02-15 4 M 0 7535 A 47513.221 D Common Stock 2022-02-15 4 M 0 4281 A 51794.221 D Common Stock 2022-02-15 4 M 0 9624 A 61418.221 D Common Stock 2022-02-15 4 M 0 3937 A 65355.221 D Common Stock 2022-02-15 4 F 0 13839 152.55 D 51516.221 D Restricted Stock Unit 2022-02-15 4 M 0 3065.722 D Common Stock 3065.722 67072.89 D Restricted Stock Unit 2022-02-15 4 M 0 2754.821 D Common Stock 2754.821 64318.069 D Restricted Stock Unit 2022-02-15 4 M 0 7535 D Common Stock 7535 56783.069 D Restricted Stock Unit 2022-02-15 4 M 0 4281 D Common Stock 4281 52502.069 D Restricted Stock Unit 2022-02-15 4 M 0 9624 D Common Stock 9624 42878.069 D Restricted Stock Unit 2022-02-15 4 M 0 3937 D Common Stock 3937 38941.069 D Each restricted stock unit (RSU) represents the contingent right to receive one share of common stock of MKS Instruments, Inc. This transaction was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person. These RSUs were subject to performance criteria, the achievement of which was determined on January 27, 2020, and thereafter vest in three equal annual installments beginning on February 15, 2020, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day. These RSUs vest in three equal annual installments commencing on February 15, 2020, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day. These RSUs were subject to performance criteria, the achievement of which was determined on January 25, 2021, and thereafter vest in three equal annual installments beginning on February 15, 2021, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day. These RSUs vest in three equal annual installments commencing on February 15, 2021, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day. These RSUs were subject to performance criteria, the achievement of which was determined on January 21, 2022, and thereafter vest in three equal annual installments beginning on February 15, 2022, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day. These RSUs vest in three equal annual installments commencing on February 15, 2022, provided that if, in any vesting year, February 15th is not a business day, such vesting shall occur on the next business day. /s/ M. Kathryn Rickards, attorney-in-fact 2022-02-16