MKS INC — Director's Dealing 2010

Apr 28, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2010-04-26

Reporting Person: SMITH JOHN ALEXANDER (V.P. & Chief Tech Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-04-26	Common Stock	M	461	$18.44	Acquired	461	Direct
2010-04-26	Common Stock	M	2188	$14.72	Acquired	2649	Direct
2010-04-26	Common Stock	S	2649	$24.33	Disposed	0	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-04-26	Stock Option (Right to Buy)	$18.44	M	461	Disposed	2012-06-24	Common Stock (461)	Direct
2010-04-26	Stock Option (Right to Buy)	$14.72	M	2188	Disposed	2014-07-30	Common Stock (2188)	Direct

Footnotes

F1: Vests 100% after one year.

F2: 25% after first year, 6.25% each quarter thereafter - total 4 years.