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: Loomis Paul (VP & GM, Astex)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-02-25	Common Stock	M	1557.213	—	Acquired	5683.213	Direct
2013-02-25	Common Stock	M	1059	—	Acquired	6742.213	Direct
2013-02-25	Common Stock	F	830	$26.92	Disposed	5912.213	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-02-25	Restricted Stock Unit	$	M	1557.213	Disposed		Common Stock (1557.213)	Direct
2013-02-25	Restricted Stock Unit	$	M	1059	Disposed		Common Stock (1059)	Direct
2013-02-25	Restricted Stock Unit	$	A	4773.403	Acquired		Common Stock (4773.403)	Direct
2013-02-25	Restricted Stock Unit	$	A	7160.104	Acquired		Common Stock (7160.104)	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 equal annual installments over three years