MKS INC — Director's Dealing 2011

Mar 30, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2011-03-28

Reporting Person: Eyerman Paul (VP & GM, ENI and Medical)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-03-28	Common Stock	M	4250	—	Acquired	6484.724	Direct
2011-03-28	Common Stock	F	1540	$32.32	Disposed	4944.724	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-03-28	Restricted Stock Unit	$	M	4250	Disposed		Common Stock (4250)	Direct

Footnotes

F1: Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc.

F2: This transaction was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person.

F3: The RSUs vest in 3 years after grant date (broken out by amount and corresponding grant date as follows: 5,000 on April 9, 2010, 4,000 on May 26, 2009, 4,250 on March 28, 2008 and 5,000 on March 5, 2007).