MKS Instruments (MKSI) DEFA14A Additional proxy soliciting materials

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 14A

(Rule14A-101)

INFORMATION REQUIRED IN

PROXY STATEMENT

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.     )

Filed by the Registrant  ☑                            Filed by a Party other than the Registrant  ☐

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☐	Preliminary Proxy Statement
☐	Confidential, for Use of the Commission Only (as permitted by Rule14a-6(e)(2))
☐	Definitive Proxy Statement
☑	Definitive Additional Materials
☐	Soliciting Material Pursuant to§240.14a-12
MKS Instruments, Inc.
(Name of Registrant as Specified in its Charter)
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MKS INSTRUMENTS, INC.

SUPPLEMENTAL MATERIAL TO OUR PROXY STATEMENT

FOR OUR ANNUAL MEETING TO BE HELD ON MAY 8, 2019

This Supplement dated April 30, 2019 amends and supplements the Proxy Statement of MKS Instruments, Inc. (the “Company”) dated March 28, 2019 (the “Proxy Statement”), with the following information:

Engagement of Proxy Solicitor

Subsequent to filing the Proxy Statement for our 2019 Annual Meeting of Shareholders to be held on May 8, 2019, the Company engaged Georgeson LLC (“Georgeson”), an independent proxy solicitation firm, to assist in soliciting proxies on our behalf. The Company has agreed to pay Georgeson a fee of $15,000, plus costs and expenses, for these services. In addition, we have agreed to indemnify Georgeson and certain related persons against certain liabilities relating to or arising out of Georgeson’s engagement. Other costs of soliciting votes in connection with the Proxy Statement have been, or will be, paid by the Company.

Important Information

The Company has filed the definitive Proxy Statement with the Securities and Exchange Commission (the “SEC”) and has furnished to its shareholders the Proxy Statement in connection with the solicitation of proxies for its 2019 Annual Meeting of Shareholders. The Company advises its shareholders to read the Proxy Statement relating to the 2019 Annual Meeting, as amended and supplemented by this Supplement, because it contains important information. Shareholders may obtain a free copy of the Proxy Statement and other documents that the Company files with the SEC at the SEC’s website at www.sec.gov.