MKS INC — Director's Dealing 2010

Feb 12, 2010

SEC Form 5 — Annual Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2009-12-31

Reporting Person: WEIGNER RONALD (V.P., C.F.O & Treasurer)

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2009-03-16	Restricted Stock Unit	$	A	1400	Acquired		Common Stock (1400)	Direct

Footnotes

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

F2: These shares were inadvertently not reported with the equity grant on March 16, 2009

F3: These shares are subject to the achievement of performance criteria, and thereafter shall vest in equal annual installments over three years.