X0303 4 2011-05-02 0001049502 MKS INSTRUMENTS INC MKSI 0001106180 BERTUCCI JOHN R 2 TECH DRIVE ANDOVER MA 01810 1 Common Stock 2011-05-02 4 A 0 6000 A 228422 D This RSU grant fully vests on the day prior to the first annual meeting of shareholders following the date of grant (or if no such meeting is held within 13 months after the date of grant, on the 13 month anniversary of the date of grant). Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc. /s/Renee M. Donlan POA 2011-05-03