X0201 4 2004-01-21 0 0001049502 MKS INSTRUMENTS INC MKSI 0001106180 BERTUCCI JOHN R SIX SHATTUCK ROAD ANDOVER MA 018102449 1 1 1 0 President & CEO Common 2004-01-21 4 S 0 571428 26.25 D 4438100.00 D Common 2004-01-21 4 S 0 571429 26.25 D 4636498.00 I By Spouse Common 4710.00 I By Limited Partnership Common 372180.00 I By Trust Stock Dispositions pursuant to Publically announced Stock Offering. By: Joseph M.Tocci / POA 2004-01-22