X0306 4 2018-10-01 0001049502 MKS INSTRUMENTS INC MKSI 0001754514 Batra Raj 2 TECH DRIVE, SUITE 201 ANDOVER MA 01810 1 Common Stock 2018-10-01 4 A 0 2114.165 A 2114.165 D These restricted stock units become fully vested on the day prior to the first annual meeting of shareholders following the date of grant (or on June 9, 2019 if no such meeting is held by June 9, 2019). Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc. /s/ M. Kathryn Rickards, attorney-in-fact 2018-10-02