X0303 4 2009-03-16 0001049502 MKS INSTRUMENTS INC MKSI 0001202738 BERLINGHIERI LEO 2 TECH DRIVE ANDOVER MA 01810 1 1 President and CEO Restricted Stock Unit 2009-03-16 4 A 0 36540 0 A Common Stock 36540 77060 D Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc. One half of RSUs shall vest in equal annual installments over three years, and the other half shall be subject to the achievement of performance criteria, and thereafter shall vest in equal annual installments over three years. /s/Renee M. Donlan POA 2009-03-18