UNITED STATES

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): July 30, 2018

MKS Instruments, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: 978-645-5500

Not Applicable

Former name or former address, if changed since last report

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 5.02 Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(d) On July 30, 2018, the Board of Directors (the “Board”) of MKS Instruments, Inc. (the “Company”) elected Rajeev “Raj” Batra as a Class I Director, with a term that will begin October 1, 2018, to fill the vacancy in the Board, and to serve until the 2021 Annual Meeting of Shareholders. Mr. Batra is not expected to initially serve on any Board committee.

There are no transactions involving the Company and Mr. Batra that are required to be disclosed pursuant to Item 404(a) of Regulation S-K.

Mr. Batra will be entitled to receive compensation for his Board and any committee service in accordance with the Company’s standard compensation arrangements for non-employee directors, which are described under the caption “Director Compensation” in the Company’s definitive proxy statement on Schedule 14A filed with the Securities and Exchange Commission on March 28, 2018, as adjusted by the Board from time to time.

A copy of the press release announcing Mr. Batra’s election to the Board is furnished as Exhibit 99.1 to this Current Report on Form 8-K.

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 LOGO)

EXHIBIT 99.1

MKS Instruments Announces Appointment of Raj Batra to its Board of Directors

Andover, Mass., July 31, 2018 — MKS Instruments, Inc. (NASDAQ: MKSI), a global provider of technologies that enable advanced processes and improve productivity, announced today that Raj Batra, President of the Digital Factory Division of Siemens in the U.S., was appointed to its Board of Directors, with a term that will begin on October 1, 2018.

“Raj is an outstanding global leader who has demonstrated vision and execution acumen for a Fortune 100 company,” said Jerry Colella, CEO, MKS Instruments. “Our industrial technology business is a key strategic focus for us and we are pleased to bring Raj’s strong experience in this area to our Board. We look forward to his insight and guidance.”

Background on Mr. Batra

Mr. Batra is the President of the Digital Factory Division of Siemens in the U.S. Siemens’ worldwide focus is on the areas of electrification, automation, and digitalization. From 1993 to 2014, Mr. Batra served in various senior roles at Siemens in the U.S., including President of the Industrial Automation Division from October 2009 to October 2014, Vice President and General Manager, Automation & Motion from October 2007 to October 2009, and Vice President and General Manager, Automation & Aerospace Vertical Division from October 2002 to October 2007. Mr. Batra received a B.S. in Electrical Engineering and Electronic Engineering from Lawrence Technological University and an MBA from the University of Michigan.

About MKS Instruments

MKS Instruments, Inc. is a global provider of instruments, subsystems and process control solutions that measure, monitor, deliver, analyze, power and control critical parameters of advanced manufacturing processes to improve process performance and productivity for our customers. Our products are derived from our core competencies in pressure measurement and control, flow measurement and control, gas and vapor delivery, gas composition analysis, residual gas analysis, leak detection, control technology, ozone generation and delivery, power, reactive gas generation, vacuum technology, lasers, photonics, sub-micron positioning, vibration control and optics. We also provide services relating to the maintenance and repair of our products, installation services and training. Our primary served markets include semiconductor, industrial technologies, life and health sciences, research and defense. Additional information can be found at www.mksinst.com.

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Company Contact: Seth H. Bagshaw

Senior Vice President, Chief Financial Officer and Treasurer

Telephone: +1 978.645.5578

Email: seth_bagshaw@mksinst.com

Investor Relations Contact: The Blueshirt Group

Monica Gould

Telephone: +1 212.871.3927

Email: monica@blueshirtgroup.com

Lindsay Savarese

Telephone: +1 212.331.8417

Email: lindsay@blueshirtgroup.com