X0202 4 2006-08-09 0 0001049502 MKS INSTRUMENTS INC MKSI 0001202758 WEIGNER RONALD 90 INDUSTRIAL WAY WILMINGTON MA 01887 0 1 0 0 V.P. & Chief Financial Officer Common 2006-08-09 4 M 0 660 4.43 A 10661.00 D Common 2006-08-09 4 S 0 660 19.63 D 10001.00 D Stock Option (right to buy) 2006-08-09 4 M 0 660 0 D 1988-08-08 1988-08-08 Common 660.00 306693.00 D The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person. Option conversion price $4.43 for option transactions reported on this filing. Stock Option Grants include multiple vest dates. Expires 10 years after date of grant By: Joseph M.Tocci / POA 2006-08-09