-------------------------------------------------------------------------------- -------------------------------------------------------------------------------- SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 ------------------------------------ FORM 8-K ------------------------------------ CURRENT REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 DATE OF REPORT (DATE OF EARLIEST EVENT REPORTED): NOVEMBER 27, 2001 COMMISSION FILE NO. MKS INSTRUMENTS, INC. (Exact name of Registrant as specified in its Charter) MASSACHUSETTS 04-2277512 (State or other jurisdiction of (IRS Employer Identification No.) incorporation or organization) SIX SHATTUCK ROAD, ANDOVER, MASSACHUSETTS 01810 (Address of principal executive offices) (Zip Code) (978) 975-2350 (Registrant's telephone number, including area code) -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- ITEM 5. OTHER EVENTS This current report on Form 8-K provides financial information pertaining to the retroactive effect of the January 26, 2001 business combination of MKS Instruments, Inc. (the "Company") and Applied Science and Technology, Inc. ("ASTeX"), which was accounted for under the pooling of interest method of accounting. ITEM 7. FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS (c) Exhibits EXHIBIT NUMBER TITLE ------- ----- 23.1 Consent of PricewaterhouseCoopers LLP 23.2 Consent of KPMG LLP 99.1 Consolidated Financial Statements of MKS Instruments, Inc. as of December 31, 2000 and 1999 and for the years ended December 31, 2000, 1999 and 1998 and Report of Independent Accountants thereon. 99.2 Management's Discussion and Analysis of Financial Condition and Results of Operations Reflecting the Merger of MKS Instruments, Inc. and Applied Science and Technology, Inc. -- December 31, 2000 99.3 Schedule II -- Valuation and Qualifying Accounts for MKS Instruments, Inc. SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. MKS INSTRUMENTS, INC. /s/ Ronald C. Weigner Ronald C. Weigner Vice President and Chief Financial Officer Dated: November 27, 2001 EXHIBIT INDEX EXHIBIT NUMBER TITLE ------- ----- 23.1 Consent of PricewaterhouseCoopers LLP 23.2 Consent of KPMG LLP 99.1 Consolidated Financial Statements of MKS Instruments, Inc. as of December 31, 2000 and 1999 and for the years ended December 31, 2000, 1999 and 1998 and Report of Independent Accountants thereon. 99.2 Management's Discussion and Analysis of Financial Condition and Results of Operations Reflecting the Merger of MKS Instruments, Inc. and Applied Science and Technology, Inc. -- December 31, 2000 99.3 Schedule II -- Valuation and Qualifying Accounts for MKS Instruments, Inc.