MKS INC — Director's Dealing 2011

Oct 12, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

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

Reporting Person: Lee John Tseng-Chung (Group VP)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-10-10	Common Stock	M	3750	—	Acquired	4331.936	Direct
2011-10-10	Common Stock	F	1191	$23.72	Disposed	3140.936	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-10-10	Restricted Stock Unit	$	M	3750	Disposed		Common Stock (3750)	Direct

Footnotes

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

F2: Each restricted stock unit represents the contingent right to receive one share of common stock of MKS Instruments, Inc.

F3: RSU vests in equal annual installments over 4 years.

F4: RSU vests in equal annual installments over 4 years.