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: Lee John Tseng-Chung (Sr. VP, HPS, Controls & PFMC)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-02-25	Common Stock	M	1946.267	—	Acquired	2425.398	Direct
2013-02-25	Common Stock	M	1324	—	Acquired	3749.398	Direct
2013-02-25	Common Stock	F	1060	$26.92	Disposed	2689.398	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-02-25	Restricted Stock Unit	$	M	1946.267	Disposed		Common Stock (1946.267)	Direct
2013-02-25	Restricted Stock Unit	$	M	1324	Disposed		Common Stock (1324)	Direct
2013-02-25	Restricted Stock Unit	$	A	6315.007	Acquired		Common Stock (6315.007)	Direct
2013-02-25	Restricted Stock Unit	$	A	9472.511	Acquired		Common Stock (9472.511)	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.