MKS INC — Director's Dealing 2013

Feb 26, 2013

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2013-02-25

Reporting Person: BAGSHAW SETH H (Vice President, CFO, Treasurer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-02-25	Common Stock	M	3114.427	—	Acquired	15130.363	Direct
2013-02-25	Common Stock	M	2119	—	Acquired	17249.363	Direct
2013-02-25	Common Stock	F	1697	$26.92	Disposed	15552.363	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-02-25	Restricted Stock Unit	$	M	3114.427	Disposed		Common Stock (3114.427)	Direct
2013-02-25	Restricted Stock Unit	$	M	2119	Disposed		Common Stock (2119)	Direct
2013-02-25	Restricted Stock Unit	$	A	11144.131	Acquired		Common Stock (11144.131)	Direct
2013-02-25	Restricted Stock Unit	$	A	16716.196	Acquired		Common Stock (16716.196)	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: 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 3 years after grant date.