MKS INC — Director's Dealing 2012

Feb 21, 2012

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2012-02-17

Reporting Person: BERLINGHIERI LEO (Director, President and CEO)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2012-02-17	Common Stock	M	5400	$29.93	Acquired	42337	Direct
2012-02-17	Common Stock	S	3200	$32.048	Disposed	39137	Direct
2012-02-17	Common Stock	M	3200	$27.11	Acquired	42337	Direct
2012-02-17	Common Stock	S	5400	$32.038	Disposed	36937	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2012-02-17	Stock Option (Right to Buy)	$29.93	M	5400	Disposed	2014-01-06	Common Stock (5400)	Direct
2012-02-17	Stock Option (Right to Buy)	$27.11	M	3200	Disposed	2013-11-11	Common Stock (3200)	Direct

Footnotes

F1: This transaction was executed in multiple trades at prices ranging from $32.00 to $32.12 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 $32.00 to $32.12 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: Vests 100% one year after grant

F4: 25% after first year, 6.25% each quarter thereafter - total 4 years.