MKS INC — Director's Dealing 2012

Feb 27, 2012

SEC Form 4/A — Form 4/A

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2012-02-27

Reporting Person: BAGSHAW SETH H (Vice President, CFO, Treasurer)

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2012-02-27	Restricted Stock Unit	$	J	266.489	Disposed		Common Stock (266.489)	Direct

Footnotes

F1: Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc.

F2: 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.

F3: This transaction reflects the forfeiture of RSUs due to performance criteria.

F4: Amendment is being filed to report additional shares forfeited, but not reported on original filing.