SCHEDULE 14A INFORMATION

 

Proxy Statement Pursuant to Section 14(a) of the Securities

Exchange Act of 1934 (Amendment No.     )

 

 

 

Check the appropriate box:

 

MKS Instruments, Inc.

(Name of Registrant as Specified In Its Charter)

 

(Name of Person(s) Filing Proxy Statement)

 

Payment of Filing Fee (Check the appropriate box):

þ No fee required.

o Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.

 

    1) Title of each class of securities to which transaction applies:

 

    2) Aggregate number of securities to which transaction applies:

 

    3) Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (Set forth the amount on
      which the filing fee is calculated and state how it was determined):

 

    4) Proposed maximum aggregate value of transaction:

 

    5) Total fee paid:

 

o Fee paid previously with preliminary materials.

 

o Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee
    was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

 

    1) Amount Previously Paid:

 

    2) Form, Schedule or Registration Statement No.:

 

    3) Filing Party:

 

    4) Date Filed:

 

MKS Instruments, Inc. (the “Company”) has amended its Proxy Statement, dated March 23, 2009 as follows. The Company has revised one feature of its proposed amendment to the Company’s 2004 Stock Incentive Plan which allows for an option exchange program. The Company has determined that any and all options surrendered to the Company pursuant to the option exchange program shall not become available for the grant of future awards under the 2004 Stock Incentive Plan or any other Company plan.