MKS INC — Director's Dealing 2012

Feb 7, 2012

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2012-02-06

Reporting Person: ANDERSON ROBERT R (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2012-02-06	Common Stock	M	5000	$20.07	Acquired	26000	Direct
2012-02-06	Common Stock	M	4000	$15.84	Acquired	30000	Direct
2012-02-06	Common Stock	S	5000	$31.992	Disposed	25000	Direct
2012-02-06	Common Stock	S	4000	$31.972	Disposed	21000	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2012-02-06	Director Stock Option (Right to Buy)	$20.07	M	5000	Disposed	2014-05-14	Common Stock (5000)	Direct
2012-02-06	Director Stock Option (Right to Buy)	$15.84	M	4000	Disposed	2015-05-08	Common Stock (4000)	Direct

Footnotes

F1: This transaction was executed in multiple trades at prices ranging from $31.99 to $32.01 The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide, upon request, the full information regarding the number of shares and prices at which the transaction was effected.

F2: This transaction was executed in multiple trades at prices ranging from $31.96 to $32.00 The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide, upon request, the full information regarding the number of shares and prices at which the transaction was effected.

F3: Option vests in full on the earlier of (i) the day before the subsequent year's annual meeting of shareholders or (ii) thirteen months from the date of grant.