MKS INC — Director's Dealing 2010

Mar 18, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2010-03-16

Reporting Person: COLELLA GERARD G (VP, Chief Operating Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-03-16	Common Stock	M	2858	—	Acquired	2869	Direct
2010-03-16	Common Stock	M	2041	—	Acquired	4910	Direct
2010-03-16	Common Stock	F	1557	$19.29	Disposed	3353	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-03-16	Restricted Stock Unit	$	M	2858	Disposed		Common Stock (2858)	Direct
2010-03-16	Restricted Stock Unit	$	M	2041	Disposed		Common Stock (2041)	Direct

Footnotes

F1: This transaction was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person.

F2: Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc.

F3: These RSUs are subject to the achievement of performance criteria determined in the first year of the grant and thereafter vests in equal annual installments over three years.

F4: The RSUs vest in equal annual installments over three years.