MKS INC — Director's Dealing 2011

Oct 31, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2011-10-28

Reporting Person: ANDERSON ROBERT R (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-10-28	Common Stock	M	7000	$20.07	Acquired	28000	Direct
2011-10-28	Common Stock	S	7000	$27.183	Disposed	21000	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-10-28	Director Stock Option (Right to Buy)	$20.07	M	7000	Disposed	2014-05-14	Common Stock (7000)	Direct

Footnotes

F1: This transaction was executed in multiple trades at prices ranging from $27.13 to $27.23 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: 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.