MKS INC — Director's Dealing 2010

Mar 12, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: MKS INSTRUMENTS INC (MKSI)
CIK: 0001049502
Period of Report: 2010-03-10

Reporting Person: COLELLA GERARD G (VP, Chief Operating Officer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-03-10	Common Stock	M	2024	—	Acquired	2035	Direct
2010-03-10	Common Stock	M	2917	—	Acquired	4952	Direct
2010-03-10	Common Stock	F	1570	$19.07	Disposed	3382	Direct
2010-03-11	Common Stock	S	3371	$19.03	Disposed	11	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2010-03-10	Restricted Stock Unit	$	M	2024	Disposed		Common Stock (2024)	Direct
2010-03-10	Restricted Stock Unit	$	M	2917	Disposed		Common Stock (2917)	Direct

Footnotes

F1: This transaction was effected pursuant to a Rule 10b5-1 trading plan previously adopted by the reporting person to satisfy tax withholding obligations.

F2: This transaction was executed in multiple trades at prices ranging from $19.02 to $19.04. 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: Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc.

F4: 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.

F5: The RSUs vest in equal annual installments over three years.