UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 14A

(Rule 14A-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  þ☑                            Filed by a Party other than the Registrant  ¨☐

Check the appropriate box:

MKS INSTRUMENTS, INC.

2 TECH DRIVE, SUITETech Drive, Suite 201

ANDOVER, MASSACHUSETTSAndover, Massachusetts 01810

March 13, 201528, 2018

Dear Shareholder:

You are cordially invited to attend the 20152018 Annual Meeting of Shareholders of MKS Instruments, Inc. to be held on Monday,Wednesday, May 4, 20159, 2018 at 10:00 a.m., local time,Eastern Time, at the Wyndham Boston Andover Hotel, 123 Old River Road,MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, Massachusetts 01810.

The enclosedattached notice of Annual Meeting and proxy statement describe the business to be transacted at the Annual Meeting and provide additional information about us that you should know when voting your shares. The principal business at the Annual Meeting will be (i) to electthe election of two Class I Directors, each for a three-year term, (ii) to approve the 162(m) Executive Cash Incentive Plan, (iii) to approve a non-bindingapproval, on an advisory vote onbasis, of executive compensation and (iv) to ratify(iii) the ratification of the selection of PricewaterhouseCoopers LLP as our independent registered public accounting firm for the year ending December 31, 2015.2018.

Whether or not you plan to attend the Annual Meeting, please complete, date, signcarefully review the attached proxy materials and returntake the time to cast your Proxy Card promptly in the enclosed envelope, which requires no postage if mailed in the United States.vote. If you attend the Annual Meeting, you may vote in person if you wish, even if you have previously returned your Proxy Card,voted, in which case your proxy vote will be revoked.

On behalf of MKS, I would like to express our appreciation for your continued interest in our Company.

Sincerely,

GERALD G. COLELLA

Chief Executive Officer and President

MKS INSTRUMENTS, INC.

2 TECH DRIVE, SUITETech Drive, Suite 201

ANDOVER, MASSACHUSETTSAndover, Massachusetts 01810

NOTICE OF 20152018 ANNUAL MEETING OF SHAREHOLDERS

TO BE HELD ON MAY 4, 20159, 2018

To our Shareholders:

NOTICE IS HEREBY GIVEN that the 2015The 2018 Annual Meeting of Shareholders of MKS INSTRUMENTS, INC., a Massachusetts corporation, will be held on Monday,Wednesday, May 4, 20159, 2018 at 10:00 a.m., local time,Eastern Time, at the Wyndham Boston Andover Hotel, 123 Old River Road,MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, Massachusetts 01810. At the meeting, shareholders will consider and vote on01810 for the following matters:purposes:

The shareholders will also act on any other business as may properly come before the meeting.

Instead of mailing a paper copy of our proxy materials to all of our shareholders, this year we are providing access to our proxy materials over the Internet under the U.S. Securities and Exchange Commission’s “notice and access” rules. As a result, we are mailing to our shareholders a Notice of Internet Availability of Proxy Materials, which we refer to as the Notice, instead of a paper copy of this proxy statement and our Annual Report for the fiscal year ended December 31, 2017, which we refer to as the 2017 Annual Report. We are mailing the Notice on or about March 28, 2018, and it contains instructions on how to access the proxy materials over the Internet. The Notice also contains instructions on how each of our shareholders can receive a paper copy of our proxy materials, including this proxy statement, our 2017 Annual Report, and a form of proxy card or voting instruction card. All shareholders who do not receive the Notice, including shareholders who have previously requested to receive paper copies of proxy materials, will receive a paper copy of the proxy materials by mail unless they have previously requested delivery of proxy materials electronically. We have chosen to employ this distribution process to conserve natural resources and reduce the costs of printing and distributing our proxy materials.

The Board of Directors has fixed the close of business on March 11, 20157, 2018 as the record date for the determination of shareholders entitled to notice of, and to vote at, the Annual Meeting and any adjournment or postponement thereof. Our stock transfer books will remain open forYour vote is important no matter how many shares you own. Whether you expect to attend the purchasemeeting or not, please vote your shares by using the Internet as described in the instructions included on your Notice, by calling the toll-free telephone number, or, if you received a paper copy of the proxy materials, by completing, signing, dating and sale of our Common Stock.returning your proxy card or voting instruction form. Your prompt response is necessary to ensure that your shares are represented at the meeting. You can change your vote and revoke your proxy any time before the polls close at the meeting by following the procedures described in the accompanying proxy statement.

If you would like to attend the Annual Meeting and your shares are held by a broker, bank or other nominee, you must bring to the Annual Meeting a letter from the nominee confirming your beneficial ownership of such shares. In order to vote your shares at the Annual Meeting, you must obtain from the nominee a proxy issued in your name. You must also bring a form of personal identification.

By Order of the Board of Directors,

RICHARD S. CHUTE

Secretary

Andover, Massachusetts

March 13, 201528, 2018

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MKS INSTRUMENTS, INC.

2 TECH DRIVE, SUITETech Drive, Suite 201

ANDOVER, MASSACHUSETTSAndover, Massachusetts 01810

PROXY STATEMENT

This proxy statement is furnished in connection with the solicitation of proxies by the Board of Directors of MKS Instruments, Inc., a Massachusetts corporation, for use at the 20152018 Annual Meeting of Shareholders to be held on May 4, 20159, 2018 at 10:00 a.m., local time,Eastern Time, at the Wyndham Boston Andover Hotel, 123 Old River Road,MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, Massachusetts 01810, and at any adjournment or postponement thereof, (the “Annual Meeting”).which we refer to as the Annual Meeting. References in this proxy statement to “we,” “us,” the “Company” or “MKS” refer to MKS Instruments, Inc. and its consolidated subsidiaries.

All proxies will be voted in accordance with the shareholders’applicable shareholder’s instructions. If no choice is specified in the proxy, the shares will be voted in favor of the matters set forth in the accompanying Notice of 20152018 Annual Meeting of Shareholders. Any proxy may be revoked by a shareholder at any time before its exercise by delivery of written revocation to the Secretary of MKS. Attendance at the Annual Meeting will not in itself be deemed to revoke a proxy unless the shareholder gives affirmative notice at the Annual Meeting that the shareholder intends to revoke the proxy and vote in person.

Instead of mailing a paper copy of our proxy materials to all of our shareholders, this year we are providing access to our proxy materials over the Internet under the “notice and access” rules of the U.S. Securities and Exchange Commission, which we refer to as the SEC. As a result, we are mailing to our shareholders a Notice of Internet Availability of Proxy Materials, which we refer to as the Notice, instead of a paper copy of this proxy statement and our Annual Report for the fiscal year ended December 31, 2017, which we refer to as the 2017 Annual Report. We are mailing the Notice on or about March 28, 2018, and it contains instructions on how to access those documents over the Internet. The Notice also contains instructions on how each of our shareholders can receive a paper copy of our proxy materials, including this proxy statement, our 2017 Annual Report, and a form of proxy card or voting instruction card. All shareholders who do not receive the Notice, including shareholders who have previously requested to receive paper copies of proxy materials, will receive a paper copy of the proxy materials by mail unless they have previously requested delivery of proxy materials electronically.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL MEETING OF SHAREHOLDERS TO BE HELD ON MAY 9, 2018

This proxy statement and the 2017 Annual Report to Shareholders are available for viewing, printing and downloading athttp://investor.mksinst.com/financial-information/annual-reports.

A COPY OF OUR ANNUAL REPORT ON FORM10-K FOR THE YEAR ENDED DECEMBER 31, 2017 AS FILED WITH THE SEC, EXCLUDING EXHIBITS, WILL BE FURNISHED WITHOUT CHARGE TO ANY SHAREHOLDER UPON WRITTEN REQUEST TO: INVESTOR RELATIONS DEPARTMENT, MKS INSTRUMENTS, INC., 2 TECH DRIVE, SUITE 201, ANDOVER, MA 01810. EXHIBITS WILL BE PROVIDED UPON WRITTEN REQUEST AND PAYMENT OF AN APPROPRIATE PROCESSING FEE.

VOTING OF SECURITIES AND VOTES REQUIRED

At the close of business on March 11, 2015,7, 2018, the record date for the determination of shareholders entitled to notice of, and to vote at, the Annual Meeting, there were issued and outstanding and entitled to vote 53,289,38854,488,757 shares of our common stock, no par value per share, (the “Common Stock”).which we refer to as our Common Stock. Each outstanding share entitles the record holder to one vote on each matter submitted at the Annual Meeting.

In order to transact business at the Annual Meeting, we must have a quorum. Under our Amended and RestatedBy-Laws, the holders of a majority of the shares of Common Stock issued and outstanding and entitled to vote at the Annual Meeting shall constitute a quorum for the transaction of business at the Annual Meeting. Shares of Common Stock held by shareholders present in person or represented by proxy (including “brokernon-votes” and shares that abstain or do not vote with respect to a particular proposal to be voted upon) will be counted for purposes of determining whether a quorum exists at the Annual Meeting. If a quorum is not present, the meeting will be adjourned until a quorum is obtained.

The affirmative vote of the holders of a plurality of the votes cast on the matter is required for the election of directors (Proposal One); provided, however, any director nominee who receives a greater number of withhold votes than affirmative votes, (a “Majoritywhich we refer to as a Majority Withhold Vote”)Vote, in an uncontested election must offer to tender to the Board of Directors his or her resignation promptly following the certification of election results. The Board of Directors must accept or reject a resignation within 90 days following the certification of election results and publicly disclose its decision. Accordingly, the nominees who receive the highest number of votes of the shares present, in person or by proxy, and entitled to vote shall be elected to the available Class I Director positions, and in the event any nominee receives a Majority Withhold Vote, the resignation policy will apply as summarized here and as set forth in Section B.4 of our Corporate Governance Guidelines which are posted on our website athttp://mksinst.cominvestor.mksinst.com in the Corporate Governance Section under the Investors tab. The approval of the 162(m) Executive Cash Incentive Plan (Proposal Two), the approval of the advisory vote on executive compensation (Proposal Three),Two) and the ratification of PricewaterhouseCoopers LLP (Proposal Four)Three) require the affirmative vote of the holders of a majority of the votes cast on the matter. Proposal Two is anon-binding proposal.

Shares held by shareholders who abstain from voting as to a particular matter, and “brokernon-votes,” which are shares held in “street name” by banks, brokers or nominees, who indicate on their proxies that they do not have discretionary authority to vote such shares as to a particularnon-routine matter, including the election of directors the vote to approve the 162(m) Executive Cash Incentive Plan, and the advisory vote on executive compensation, will not be counted as votes in favor of, or as votes cast for, a matter. Accordingly, abstentions and brokernon-votes will have no effect on the voting on a matter that requires the affirmative vote of a certain percentagemajority of the shares votingvotes cast on the matter. Proposal Three is a non-binding proposal. If the shares you own

are held in street name by a bank or brokerage firm, your bank or brokerage firm, as the record holder of your shares, is required to vote your shares according to your instructions. In order to vote your shares, you will need to follow the directions your bank or brokerage firm provides you.

THE NOTICE OF ANNUAL MEETING, THIS PROXY STATEMENT AND OUR ANNUAL REPORT

TO SHAREHOLDERS FOR THE YEAR ENDED DECEMBER 31, 2014 ARE BEING MAILED TO

SHAREHOLDERS ON OR ABOUT MARCH 17, 2015.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE SHAREHOLDER MEETING TO BE HELD ON MAY 4, 2015

A copy of (i) our Annual Report to Shareholders for the year ended December 31, 2014, which contains consolidated financial statements and other information of interest to shareholders, (ii) this Proxy Statement and this Notice, and (iii) information on how to obtain directions to be able to attend the meeting and vote in person can be accessed on our website athttp://investor.mksinst.com/annualproxy.cfm or by calling (800) 227-8766.

A COPY OF OUR ANNUAL REPORT ON FORM 10-K FOR THE YEAR ENDED DECEMBER 31, 2014 AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION, OR THE SEC, EXCLUDING EXHIBITS, WILL BE FURNISHED WITHOUT CHARGE TO ANY SHAREHOLDER UPON WRITTEN REQUEST TO: INVESTOR RELATIONS DEPARTMENT, MKS INSTRUMENTS, INC., 2 TECH DRIVE, SUITE 201, ANDOVER, MA 01810. EXHIBITS WILL BE PROVIDED UPON WRITTEN REQUEST AND PAYMENT OF AN APPROPRIATE PROCESSING FEE.

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SECURITY OWNERSHIP OF CERTAIN BENEFICIAL

OWNERS AND MANAGEMENT

The following table sets forth certain information with respect to the beneficial ownership of Common Stock by (i) each shareholder known to us to be the beneficial owner of more than 5% of the outstanding shares of Common Stock; (ii) the executive officers named in the Summary Compensation Table below; (iii) each of our current directors; and (iv) all of our directors and executive officers as a group. Unless otherwise indicated in the footnotes to the table, all equity amounts set forth in the table are as of January 1, 2015; and the address for each of our directors and executive officers is: c/o MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, Massachusetts 01810.

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To our knowledge, there are no voting trusts or similar arrangements among any of the foregoing persons or entities with respect to the voting of shares of Common Stock.

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PROPOSAL ONE

– ELECTION OF DIRECTORS

Our Amended and RestatedBy-Laws provide for a Board of Directors that is divided into three classes. The term of the Class I Directors expires at the 20152018 Annual Meeting, the term of the Class II Directors expires at the 20162019 Annual Meeting and the term of the Class III Directors expires at the 20172020 Annual Meeting. Our Board of Directors, upon the recommendation of our Nominating and Corporate Governance Committee, has nominated Gerald G. Colella and Elizabeth A. Mora are proposed for election to serve as Class I Directors for a term to expire at the 20182021 Annual Meeting. Mr. Colella and Ms. Mora currently serve as directors. Each nominee has consented to being named herein and, if elected, to serve as a director until his or her successor is duly elected and qualified.

Shares represented by all proxies received by the Board of Directors and not so marked as to withhold authority to vote for an individual director will be voted (unless one or more nominees are unable or unwilling to serve) for the election of the nominees named below. The Board of Directors expects that each of the nominees named below will be available for election, but if eitherany of them is not a candidate at the time the election occurs, it is intended that such proxies will be voted for the election of a substitute nominee to be designated by the Board of Directors.

BOARD RECOMMENDATION

THE BOARD OF DIRECTORS BELIEVES THAT APPROVAL OF THE ELECTION OF GERALD G. COLELLA AND ELIZABETH A. MORA TO SERVE AS CLASS I DIRECTORS IS IN THE BEST INTERESTS OF MKS AND OUR SHAREHOLDERS AND THEREFORE RECOMMENDS A VOTE “FOR” BOTH NOMINEES.

DIRECTORS

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DIRECTORS

The Board of Directors, upon the recommendation of the Nominating and Corporate Governance Committee, has nominated Gerald G. Colella and Elizabeth A. Mora, to serve as Class I directors. Set forth below are the names and ages of each member of our Board of Directors (including those who are nominees for election as Class I Directors) and the positions and offices held, principal occupation and business experience during at least the past five years, the names of other publicly held companies on which the individual currently serves, or in the past five years has served, as a director and the year each member of our Board of Directors joined our board.Board. We have also included information about each director’s specific experience, qualifications, attributes, or skills that led the Board of Directors to conclude that he or she should serve as a director of MKS. Information with respect to the number of shares of Common Stock beneficially owned by each director, directly or indirectly, as of January 1, 2015,2018, appears in this proxy statement under the heading “Security Ownership of Certain Beneficial Owners and Management.” Robert J. Phillippy, who currently serves as a Class I Director, is not standing forre-election to the Board of Directors and, accordingly, his tenure as a director will end as of the date of our 2018 Annual Meeting on May 9, 2018.

John R. Bertucci

Mr. Bertucci has served as our director since 1970, and has been Chairman of the Board of Directors since November 1995. Mr. Bertucci served as Executive Chairman from July 2005 until December 2006. Mr. Bertucci served as our Chief Executive Officer from November 1995 to July 2005 and served as President from 1974 to May 1999 and again from November 2001 to April 2004. From 1970 to 1974, he was our Vice President and General Manager. Mr. Bertucci holds an M.S. in Industrial Administration and a B.S. in Metallurgical Engineering from Carnegie Mellon University. Mr. Bertucci has served as a member of the Board of Trustees of Carnegie Mellon University since May 2002. He has also served as a member of the Executive Board of The Massachusetts High Technology Council since February 1999, serving as Chairman from February 2005 to February 2007. He also serves as a member of the Board of Trustees or the Board of Directors of three non-profit organizations. Mr. Bertucci’s 30-plus

Name		Year Became Director		Background and Qualifications
John R. Bertucci		1970		Mr. Bertucci has been Chairman of the Board of Directors since November 1995. Mr. Bertucci served as Executive Chairman from July 2005 until December 2006. Mr. Bertucci served as our Chief Executive Officer from November 1995 to July 2005 and served as President from 1974 to May 1999 and again from November 2001 to April 2004. From 1970 to 1974, he was our Vice President and General Manager. Mr. Bertucci holds an M.S. in Industrial Administration and a B.S. in Metallurgical Engineering from Carnegie Mellon University. Mr. Bertucci has served as a member of the Board of Trustees of Carnegie Mellon University since May 2002 and served on its Audit Committee and Executive Committee from 2007 to 2016. He also serves as a member of the Board of Trustees or the Board of Directors of threenon-profit organizations. Mr. Bertucci’s 35 years of experience working for MKS, including a combined 28 years as our President, gives him a unique insight into the challenges and strategies relevant to the semiconductor industry as a whole, and to our Company in particular.
Gregory R. Beecher		2006		Mr. Beecher has served as Chief Financial Officer of Teradyne, Inc., a semiconductor and system level test equipment provider, since 2001. Mr. Beecher was an audit partner with PricewaterhouseCoopers LLP from October 1993 to March 2001, working with numerous semiconductor equipment and instrument providers, along with other technology-related enterprises, and advising on complex accounting issues. Mr. Beecher has an M.S. in Accounting from Northeastern University. Mr. Beecher has served as a director and Chairman of the Audit Committee of Xyleco, Inc., a privately held company, since October 2016. Mr. Beecher served as a director of Hittite Microwave Corporation, a publicly traded developer of high performance integrated circuits, modules and subsystems, from June 2013 to May 2014. Mr. Beecher’s extensive financial background, including his previous experience at a public accounting firm and his current role as Chief Financial Officer of a publicly held company, provides valuable insights for our Board of Directors and the Audit Committee.
Richard S. Chute		1974		Mr. Chute was a member of the law firm of Hill & Barlow, a Professional Corporation, from 1971 to January 2003, with an extensive corporate practice, and is currently an attorney in private practice. From October 2004 to November 2016, Mr. Chute served as a director and Chairman of the Audit Committee of Massachusetts Audubon Society, Inc., and he currently serves on its Advisory Council and as a member of its Administration and Finance Committee. Mr. Chute has also served as a director and member of the Nominating and Audit Committees of Manomet, Inc., anon-profit organization, since November 1993. He has served on over 15 othernon-profit and private company boards. Mr. Chute’s extensive legal experience provides him with a unique perspective, which is particularly valuable in Mr. Chute’s current roles as Secretary of the Company and as Chair of the Nominating and Corporate Governance Committee.

Cristina H. Amon

Name		Year Became Director		Background and Qualifications
Gerald G. Colella		2014		Mr. Colella has served as our Chief Executive Officer and President since January 2014. From February 2013 until December 2013, Mr. Colella served as our President and Chief Operating Officer. He served as Vice President and Chief Operating Officer from January 2010 until February 2013 and served as our Vice President and Chief Business Officer from April 2005 until January 2010. In addition, Mr. Colella also served as our Acting Group Vice President, PRG Products, from July 2007 to March 2010. From October 1997 to April 2005, he served as our Vice President, Global Business and Service Operations; from March 1996 to October 1997, he served as our Director of Materials Planning and Logistics; and from 1994 to 1996, he served as our Materials Planning and Logistics Manager. Mr. Colella joined MKS in 1983. He holds a B.A. in Secondary Education from the University of Massachusetts and an M.B.A. from Southern New Hampshire University. Mr. Colella’s 35 years of experience within the Company gives him particularly deep insight into our organization.
Peter R. Hanley		2008		From December 2009 until November 2010, Dr. Hanley served as an occasional consultant to Novellus Systems, Inc. (now Lam Research Corporation), a leading developer of semiconductor manufacturing equipment. From January 2004 until December 2007, Dr. Hanley served as a part-time employee of Novellus, engaged primarily in executive training. Dr. Hanley served as President of Novellus from May 2001 to December 2003. Prior to that, he served as Novellus’ Executive Vice President of Worldwide Sales from June 1992 until May 2001. Prior to joining Novellus, Dr. Hanley served from 1985 to 1992 at Applied Materials, Inc., a global leader providing processing equipment to the semiconductor and display markets, most recently as Group Vice President of Worldwide Sales and Service and previously as Vice President and General Manager of their Etch Products Division. Before joining Applied Materials, Inc., Dr. Hanley served from 1978 to 1984 at Varian Associates, a leader in the semiconductor capital equipment industry, most recently as Vice President of Technology and previously as Vice President and General Manager of their Extrion Ion Implantation Division. Dr. Hanley has served as a member of the Advisory Board of Orbotech Ltd., a publicly held provider of yield-enhancing and production solutions, since 2014. Dr. Hanley holds a B.S. in Mechanical Engineering from Northeastern University and a Ph.D. in Applied Physics from Cornell University. Dr. Hanley’s substantial background in the semiconductor industry for almost 40 years, including senior management roles at Novellus and Applied Materials, two of MKS’ largest customers, provides the Board of Directors with insights into the industry’s sales and marketing challenges and opportunities.

Dr. Amon has served as our director since 2007. She has served as the Dean, Faculty of Applied Science and Engineering, Alumni Chair Professor of Bioengineering and Professor in the Department of Mechanical and Industrial Engineering at the University of Toronto since July 2006. Prior to that, Dr. Amon served at Carnegie Mellon University, as Director of the Institute for Complex Engineered Systems from September 1999 until July 2006, and was a Raymond Lane Distinguished Professor, Mechanical Engineering and Biomedical Engineering

Name		Year Became Director		Background and Qualifications
Rick D. Hess		2017		Mr. Hess has served as Strategic Advisor to the Chief Executive Officer of Analog Devices, Inc., a publicly held semiconductor company, specializing in data conversion and signal processing technology, since June 2017. From 2014 to 2017, Mr. Hess served in various senior roles at Analog Devices, including Executive Vice President from September 2016 to June 2017; Senior Vice President, Communications and Automotive Business Group from November 2014 to September 2016; and Vice President, Radio and Microwave Group from July 2014 to November 2014. Before joining Analog Devices, Mr. Hess served as the Chief Executive Officer of Hittite Microwave Corporation from February 2013 to July 2014 (when it was acquired by Analog Devices). From 2011 to 2013, he was Vice President at American Superconductor Corporation, a provider of technologies and solutions for the electrical power infrastructure industry. From 2006 to 2010, Mr. Hess was President and Chief Executive Officer of Konarka Technologies, Inc., a developer of advanced photovoltaic cells on flexible plastic. From 2004 to 2006, he was President and Chief Executive Officer of Integrated Fuel Cell Technologies, Inc., a developer of fuel cell systems. From 1989 to 2004, Mr. Hess held several positions atM/A-COM, a semiconductor provider of high frequency components and systems for the wireless, defense, public safety and automotive markets, including President from 1999 to 2004. Mr. Hess had previously founded Stable Energy Sources, a manufacturer of microwave subsystems and components serving military and industrial markets. Mr. Hess served as a member of the Board of Directors of Hittite Microwave Corporation from 2005 until 2014. Mr. Hess received a B.S. in Electrical Engineering from Purdue University and an M.S. in Electrical Engineering from Johns Hopkins University. Mr. Hess’30-plus years in executive leadership roles in the microwave, semiconductor, energy and manufacturing industries qualify him to serve as a member of our Board of Directors.
Jacqueline F. Moloney		2016		Ms. Moloney has served since 2015 as the Chancellor of the University of Massachusetts Lowell, a public university with over 17,000 students, and served as its Executive Vice Chancellor from 2007 to 2015. Ms. Moloney has been a tenured professor at the University since 1994 and served as the Dean of Online and Continuing Education from 1994 to 2007. Since 2008, Ms. Moloney has served as a director and member of the audit, strategic planning, marketing, investment, technology and executive committees of Enterprise Bancorp, Inc., a publicly held bank. She holds an Ed.D. from the University of Massachusetts Lowell. Ms. Moloney has over 30 years of experience as a leader innon-profit organizations. She has a deep history of working with business and industry, and she established the first incubators at the University of Massachusetts Lowell which are the home to approximately 50 early stage companies. She provides valuable knowledge and insight on emerging strategic planning and management and business trends.

Name		Year Became Director		Background and Qualifications
Elizabeth A. Mora		2012		Ms. Mora has served since March 2016 as the Chief Administrative Officer, and from 2008 to February 2016 served as the Chief Financial Officer, of The Charles Stark Draper Laboratory, Inc., anon-profit engineering research and development laboratory serving the national interest in applied research, engineering development, advanced technical education, and technology transfer. From 1997 until 2008, she worked for Harvard University, ultimately serving as Chief Financial Officer and Vice President for Finance, and previously serving as Associate Vice President, Research Administration and the Director of the Office of Sponsored Research. Prior to joining Harvard, Ms. Mora worked for Coopers and Lybrand (now PricewaterhouseCoopers LLP) from 1989 to 1997 and was one of the founding members of its National Regulatory Consulting Practice. Ms. Mora is a Certified Public Accountant and has an M.B.A. from the Simmons College Graduate School of Management. She has served since 2016 as a director, and since January 2017 as Chairman of the Corporate Responsibility Committee, of GCP Applied Technologies, Inc., a publicly held company that provides construction and packaging technology products. Ms. Mora’s extensive financial background, including her current role as Chief Administrative Officer of a prominent research and development organization, provides valuable insights for our Board of Directors, the Audit Committee and the Compensation Committee, and strong leadership as Chair of the Compensation Committee.

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from September 2001 until July 2006. In her roles at the University of Toronto and Carnegie Mellon, Dr. Amon has led research in micro-fabrication, sustainable energy, thermal management of electronics and nano-scale transport in silicon thin films. Dr. Amon holds a Diploma Engineering Degree from Universidad Simon Bolivar, and both an M.S. and a Sc.D. from the Massachusetts Institute of Technology, all in Mechanical Engineering. Dr. Amon has served as Executive Board Member of the Global Engineering Deans Council since 2007 and as Chair from 2008 through 2009. She has also served as an Executive Board Member of the American Society of Mechanical Engineers (ASME), Electronic and Photonic Packaging division since 2001, on the Board of Visitors for the Department of Mechanical Engineering at Stanford University since 2008, and on the Board of Visitors for the College of Engineering at the University of Illinois at Urbana-Champaign since 2009. She is a Fellow of ASEE, ASME, the American Association for the Advancement of Science, the Engineering Institute of Canada, the Institute of Electrical and Electronic Engineers, the National Academy of Engineering, the Royal Society of Canada and the Canadian Academy of Engineering. Dr. Amon’s extensive engineering background, particularly in micro-fabrication, thermal management and silicon thin-films, provides the Board of Directors with a technical perspective and insight into the challenges and opportunities we face.

Robert R. Anderson

Mr. Anderson has served as our director since January 2001. Mr. Anderson is a private investor. From October 1998 to April 2000, Mr. Anderson served as Chief Executive Officer of Yield Dynamics, Inc., a private semiconductor control software company, which MKS acquired in 2007 and later sold in 2010. Mr. Anderson served as Chief Executive Officer of Silicon Valley Research, Inc., a semiconductor design automation software company, from December 1996 to August 1998 and as Chairman from January 1994 to January 2001. Mr. Anderson was co-founder and served as Chief Financial Officer, Chief Operating Officer and Chairman of KLA Instruments, a supplier of process control and yield management solutions for the semiconductor and related nanoelectronics industries, from 1975 through 1994. He was Chief Financial Officer of Computervision from 1970 through 1975. Mr. Anderson has served as the President and a director of a private family foundation since September 2000. He has also served as a director of Aehr Test Systems, Inc., a publicly traded manufacturer of semiconductor test and burn-in equipment, since October 2000, and currently serves on Aehr’s Audit and Compensation committees. He has also served as a director of Energetiq Technology, Inc., a privately held company, since May 2005. In addition, he served as a director of Aviza Technology, Inc., a publicly traded manufacturer of semiconductor capital equipment and process technologies, from December 2005 to March 2009. Mr. Anderson is a Trustee Emeritus of Bentley University, having served as a trustee from 1992 through 2003. Mr. Anderson has served on over 18 public and private boards, and has served as Chief Financial Officer, Chief Executive Officer and Chairman of several public corporations. His extensive business experience, particularly within the semiconductor industry, provides him with insight into the challenges we face within the industry. In addition, his financial acumen is an important asset in his role as a member of our Audit and Compensation Committees.

Gregory R. Beecher

Mr. Beecher has served as our director since August 2006. Mr. Beecher has served as Chief Financial Officer of Teradyne, Inc., a semiconductor and system level test equipment provider, since 2001. Mr. Beecher was an audit partner with PricewaterhouseCoopers LLP from October 1993 to March 2001, working with numerous semiconductor equipment and instrument providers, along with other technology-related enterprises, and advising on complex accounting issues. Mr. Beecher has an M.S. in Accounting from Northeastern University. Mr. Beecher served as a director of Hittite Microwave, a publicly traded developer of high performance integrated circuits, modules and subsystems, from June 2013 to May 2014 (when it was acquired by Analog Devices, Inc.). Mr. Beecher’s extensive financial background, including his previous experience at a public accounting firm, and his current role as Chief Financial Officer of a public corporation, provide valuable insights for the Board of Directors and the Audit Committee.

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Richard S. Chute

Mr. Chute has served as our director since 1974. Mr. Chute was a member of the law firm of Hill & Barlow, a Professional Corporation, from 1971 to January 2003, with an extensive corporate practice, and is currently an attorney in private practice. Mr. Chute has served as a director of Massachusetts Audubon Society, Inc. since October 2004, currently serving as Chairman of its Audit Committee and a member of its Administration and Finance Committee, the Committee on the Board and its Diversity Committee. Mr. Chute has also served as a director and member of the Nominating Committee of Manomet, Inc., a non-profit organization, since November 1993. He has served on over 15 other non-profit and private company boards. Mr. Chute’s extensive legal experience provides him with a unique perspective, which is particularly valuable in Mr. Chute’s current roles as Secretary of the Company and as Chair of the Nominating and Corporate Governance Committee.

Gerald G. Colella

Mr. Colella has served as our director and as our Chief Executive Officer, in addition to his role as President, since January 2014. From February 2013 until December 2013, Mr. Colella served as our President and Chief Operating Officer. He served as Vice President and Chief Operating Officer from January 2010 until February 2013 and served as our Vice President and Chief Business Officer from April 2005 until January 2010. In addition, Mr. Colella also served as Acting Group Vice President, PRG Products from July 2007 to March 2010. From October 1997 to April 2005, he served as our Vice President, Global Business and Service Operations, from March 1996 to October 1997, he served as our Director of Materials Planning and Logistics and from 1994 to 1996, he served as our Materials Planning and Logistics Manager. Mr. Colella joined MKS in 1983. He holds a B.A. in Secondary Education from the University of Massachusetts and an M.B.A. from Southern New Hampshire University. Mr. Colella’s over 30 years of experience within the Company gives him particularly deep insight into the organization.

Peter R. Hanley

Dr. Hanley has served as our director since March 2008. From December 2009 until November 2010, Dr. Hanley served as an occasional consultant to Novellus Systems, Inc. (now Lam Research Corporation), a leading developer of semiconductor manufacturing equipment. From January 2004 until December 2007, Dr. Hanley served as a part-time employee of Novellus, engaged primarily in executive training. Dr. Hanley served as President of Novellus from May 2001 to December 2003. Prior to that, he served as Novellus’ Executive Vice President of Worldwide Sales from June 1992 until May 2001. Prior to joining Novellus, Dr. Hanley served from 1985 to 1992 at Applied Materials, Inc., a leader in the semiconductor capital equipment industry, most recently as Group Vice President of Worldwide Sales and Service and previously as Vice President and General Manager of their Etch Products Division. Before joining Applied Materials, Inc., Dr. Hanley served from 1978 to 1984 at Varian Associates, a leader in the semiconductor capital equipment industry, most recently as Vice President of Technology and previously as Vice President and General Manager of their Extrion Ion Implantation Division. Dr. Hanley has served as a member of the Advisory Board of Orbotech Ltd., a publicly traded provider of yield-enhancing and production solutions, since 2014. Dr. Hanley holds a Bachelor of Science degree in Mechanical Engineering from Northeastern University and a PhD in Applied Physics from Cornell University. Dr. Hanley’s substantial background in the semiconductor industry for more than 25 years, including senior management roles at Novellus and Applied Materials, two of MKS’ largest customers, provides the Board of Directors with insights into the industry’s sales and marketing challenges and opportunities.

Elizabeth A. Mora

Ms. Mora has served as our director since May 2012. Ms. Mora has served since 2008 as the Chief Financial Officer of The Charles Stark Draper Laboratory, Inc., a non-profit engineering research and development laboratory serving the national interest in applied research, engineering development, advanced technical education, and technology transfer. From 1997 until 2008, she worked for Harvard University, ultimately serving as Chief Financial Officer and Vice President for Finance at the University, and previously serving as Associate

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Vice President, Research Administration and the Director of the Office of Sponsored Research. Prior to joining Harvard, Ms. Mora worked for Coopers and Lybrand (now PricewaterhouseCoopers LLP) from 1989 to 1997 and was one of the founding members of its National Regulatory Consulting Practice. Ms. Mora is a Certified Public Accountant and has an M.B.A. from the Simmons College Graduate School of Management. She also serves as a member of the Audit Committee of the Olin College of Engineering. Ms. Mora’s extensive financial background, including her current role as Chief Financial Officer of a research and development organization, provides valuable insights for the Board of Directors and the Audit Committee.

Agreements as to Nomination

Mr. Bertucci resigned from his employment with MKS effective December 31, 2006. Mr. Bertucci’s employment agreement provided that if Mr. Bertucci resigned from his employment, then, subject to applicable law, our Amended and RestatedBy-Laws, our Restated Articles of Organization and the directors’ fiduciary duties, the Board of Directors shall nominate Mr. Bertucci for election as a Class III director and consider Mr. Bertucci for appointment as Chairman of the Board of Directors, until such time as Mr. Bertucci is no longer eligible for nomination as a director.

PROPOSAL TWO – ADVISORY VOTE ON EXECUTIVE COMPENSATION

The Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010, or the Dodd-Frank Act, which added Section 14A to the Exchange Act, enables our shareholders to vote to approve, on anon-binding, advisory basis, the compensation of our Named Executive Officers as disclosed in this proxy statement under the heading “Executive Compensation” including “Compensation Discussion and Analysis,” the tabular disclosure regarding such compensation, and the accompanying narrative disclosure. This vote is not intended to address any specific item of compensation, but rather the overall compensation of our Named Executive Officers and the philosophy, policies and practices of executive compensation described in this proxy statement. The advisory vote is not a vote on our compensation practices fornon-executive employees or our Board of Directors. The Dodd-Frank Act requires the Company to hold the advisory vote on executive compensation at least once every three years, but we have elected to submit the advisory vote to shareholders annually.

As described in detail under the heading “Executive Compensation — Compensation Discussion and Analysis,” our executive compensation programs are designed to attract, motivate, and retain our Named Executive Officers, who are critical to our success. Under these programs, our Named Executive Officers are rewarded for the achievement of specific short-term and long-term goals. Please see the “Compensation Discussion and Analysis” for additional details about our executive compensation philosophy and programs, including information about the compensation of our Named Executive Officers for the 2017 fiscal year.

The Compensation Committee continually reviews the compensation programs for our Named Executive Officers to ensure they achieve the desired goals of aligning our executive compensation structure with our shareholders’ interests and current market practices.

Our Board of Directors is asking shareholders to approve anon-binding advisory vote on the following resolution:

RESOLVED, that the compensation paid to the Company’s Named Executive Officers, as disclosed pursuant to the compensation disclosure rules of the SEC, including the Compensation Discussion and Analysis, the compensation tables and any related material disclosed in this proxy statement, is hereby approved.

This vote on the compensation of our Named Executive Officers is advisory, and therefore not binding on the Company, the Compensation Committee or our Board of Directors. Our Board of Directors and our Compensation Committee value the opinions of our shareholders and to the extent there is any significant vote against the Named Executive Officers’ compensation as disclosed in this proxy statement, we will consider our shareholders’ concerns and the Compensation Committee will evaluate whether any actions are necessary to address those concerns.

THE BOARD OF DIRECTORS BELIEVES THAT THE PROPOSAL TO APPROVE, ON ANON-BINDING ADVISORY BASIS, THE EXECUTIVE COMPENSATION CONTAINED IN THIS PROXY STATEMENT IS IN THE BEST INTERESTS OF MKS AND OUR SHAREHOLDERS AND THEREFORE RECOMMENDS A VOTE “FOR” THIS PROPOSAL.

PROPOSAL THREE – RATIFICATION OF SELECTION OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

Our Audit Committee has selected PricewaterhouseCoopers LLP, or PwC, as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2018. PwC was our independent registered public accounting firm for the fiscal year ended December 31, 2017.

Representatives of PwC are expected to be present at the Annual Meeting and will have the opportunity to make a statement if they so desire and will be available to respond to appropriate questions from shareholders. In the event that the ratification of the selection of PwC as our independent registered public accounting firm is not obtained at the Annual Meeting, the Board of Directors will reconsider its appointment.

THE BOARD OF DIRECTORS BELIEVES THAT THE PROPOSAL TO RATIFY THE SELECTION OF PWC AS OUR INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR THE FISCAL YEAR ENDING DECEMBER 31, 2018 IS IN THE BEST INTERESTS OF MKS AND OUR SHAREHOLDERS AND THEREFORE RECOMMENDS A VOTE “FOR” THIS PROPOSAL.

CORPORATE GOVERNANCE

Board Independence

The Board of Directors has determined that all of the members of the Board of Directors, other than Mr. Colella and Mr. Phillippy, are independent as defined under the rules of the NASDAQNasdaq Stock Market, (“NASDAQ”).or Nasdaq.

Board Leadership Structure

Since 2005, we have separated the roles of Chief Executive Officer and Chairman of the Board of Directors in recognition of the differences between the two roles. The Chief Executive Officer is responsible for setting the strategic direction forof the Company and theday-to-day leadership and performance of the Company, while the Chairman of the Board of Directors provides guidance to the Chief Executive Officer, sets the agenda for Board meetings and presides over meetings of the full Board of Directors.

In addition, the Board of Directors has established the position of Lead Director. Our Corporate Governance Guidelines provide that during any period in which the ChairChairman of the Board of Directors is not an independent director, and in such other instances as the Board of Directors may determine from time to time, a Lead Director shall be elected by and from the independent directors. While we are not obligated under our Corporate Governance Guidelines to have a Lead Director, as our Chairman of the Board of Directors is independent, we have currently elected to continue to do so. Mr. Beecher has served as Lead Director since 2012.

The primary role of the Lead Director is to serve as a liaison between the independent directors and the Chairman of the Board of Directors and/or the Chief Executive Officer and to represent the interestinterests of the independent directors, as appropriate. Gregory R. Beecher has served as Lead Director since 2012. Pursuant to our Corporate Governance Guidelines, which are posted on our website atwww.mksinst.cominvestor.mksinst.com in the Corporate Governance Section under the Investors tab;tab, the Lead Director shall, among other matters:

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Our Board of Directors believes that its leadership structure is appropriate at this time for our Company because it strikes an effective balance between management and independent leadership participation in the Board of DirectorsDirectors’ process.

Communications from Shareholders

The Board of Directors will give appropriate attention to written communications that are submitted by shareholders and will respond if appropriate. The Chair of the Nominating and Corporate Governance Committee, with the assistance of our General Counsel, is primarily responsible for monitoring communications from shareholders and for providing copies or summaries to the other directors as he considers appropriate. Communications are forwarded to all directors if they relate to important substantive matters and include suggestions or comments that the Chair of the Nominating and Corporate Governance Committee considers to be important for the directors to know. In general, communications relating to corporate governance and long-term corporate strategy are more likely to be forwarded than communications relating to ordinary business affairs, personal grievances and matters as to which we tend to receive repetitive or duplicative communications.

Shareholders who wish to send communications on any topic to the Board of Directors should address such communications to the Board of Directors in care of Kathleen F. Burke, Esq., Senior Vice President and General Counsel, MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, MA 01810.

Code of Ethics

We have adopted a code of business conduct and ethics that applies to all of our directors, officers and employees (including the principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions), which is posted on our website atinvestor.mksinst.com in the Corporate Governance tab. We intend to disclose on our website any amendments to, or waivers for our executive officers or directors from, our code of business conduct and ethics.

Board’s Role in Risk Oversight

Management is responsible for theday-to-day management of risks the Company faces, while the Board of Directors, as a whole and through its committees, has the ultimate responsibility for the oversight of risk management. Senior management attends quarterly meetings of the Board of Directors, provides presentations on operations including significant risks, and is available to address any questions or concerns raised by the Board of Directors. Additionally, our three standing board committees assist the Board of Directors in fulfilling its oversight responsibilities in certain areas of risk. Pursuant to its charter, the Audit Committee coordinates the Board of Directors’ oversight of the Company’s internal controls over financial reporting, disclosure controls and procedures, and code of conduct. The Audit Committee also is responsible for discussing the Company’s policies with respect to financial risk assessment and financial risk management. Management regularly reports to the Audit Committee on these areas. The Compensation Committee assists the Board of Directors in fulfilling its oversight responsibilities with respect to the management of risks arising from our compensation policies and programs as well as succession planning as it relates to our Chief Executive Officer. The Nominating and Corporate Governance Committee assists the Board of Directors in fulfilling its oversight responsibilities with respect to the management of risks associated with board organization, membership and structure, succession planning for our directors and corporate governance. In addition, from time to time, the Board of Directors may

constitute a special committee to focus on a particular matter or risk. When any of the committees receives a report related to material risk oversight, the Chairchair of the relevant committee reports on the discussion to the full Board of Directors.

Transactions with Related Persons

Our code of business conduct and ethics sets forth the general principle that our directors, officers and employees should refrain from engaging in any activity having a personal interest that presents a conflict of interest. The code of business conduct and ethics prohibits certain specified activities, and also prohibits directors, officers and employees from engaging in any other activity that may reasonably be expected to give rise to a conflict of interest or to adversely affect our interests. The code of business conduct and ethics provides that all employees are responsible to disclose to the Chief Financial Officer any material transaction or relationship that reasonably could be expected to give rise to a material conflict of interest, and officers and directors must report such transactions to the Board of Directors, which shall be responsible for determining whether such transaction or relationship constitutes a material conflict of interest.

In addition, our written Related Person Transaction Procedures set forth the procedures for reviewing transactions that could be deemed to be “related person transactions” (defined as transactions required to be disclosed pursuant to Item 404 of RegulationS-K of applicable SEC regulations). In accordance with these procedures, directors and executive officers are required to submit annual certifications regarding interests and affiliations held by them and certain of their family members. We then review our records to determine whether we have engaged in any transactions since the beginning of our prior fiscal year with such affiliated persons and entities or with any person or entity known by MKS to be the beneficial owner of more than 5% of our voting securities, and provide a summary to the Audit Committee of any such material transaction in which the related person has a direct or indirect interest. In accordance with the procedures, the Audit Committee reviews any such transactions (including, but not limited to, transactions constituting related person transactions). In reviewing any such transaction, the Audit Committee considers, among other things, the related person’s interest in the transaction, the approximate dollar value of the transaction, whether the transaction was undertaken in the ordinary course of business, whether the terms of the transaction were at arm’s length, the purpose and potential benefits to the Company of the transaction, and whether the transaction is in the best interests of the Company. The Audit Committee may, in its sole discretion, impose such conditions as it deems appropriate in connection with any related person transaction. In accordance with the Audit Committee charter, the Audit Committee reviews the Related Person Transaction Procedures from time to time.

Wellington Management Group LLP, Wellington Group Holdings LLP, Wellington Investment Advisors Holdings LLP, and Wellington Management Company LLP, which we refer to collectively as the Wellington Group, collectively beneficially owned approximately 5% of the Company’s outstanding voting shares as of December 31, 2017, according to filings they have made with the SEC. Wellington Management LLC, an affiliate of the Wellington Group, manages cash accounts of MKS in the aggregate amount of approximately $242 million as of December 31, 2017. In 2017, MKS paid Wellington Management LLC approximately $246,000 for these cash management services. Wellington Management LLC must manage the MKS cash accounts in accordance with, and subject to, the Company’s Corporate Investment Policy, which establishes clear guidelines for acceptable investments. As part of our Related Person Transaction Procedures, our Audit Committee reviewed the foregoing relationship with Wellington Management LLC.

Board of Director Meetings and Committees of the Board of Directors

The Board of Directors held sixfour meetings in 2014.2017. During 2014,2017, each director attended at least 75% of the aggregate of the total number of meetings of the Board of Directors and the total number of meetings of all committees of the Board of Directors on which he or she served. Pursuant to our Corporate Governance Guidelines, directors are encouraged to attend our Annual Meeting of Shareholders. All of the directors then serving on the Board of Directors attended the 20142017 Annual Meeting of Shareholders.

The Board of Directors has established three standing committees — Audit, Compensation, and Nominating and Corporate Governance — each of which operates under a charter that has been approved by the Board of Directors. Each committee’s current charter is posted under the Investors tab on our website atwww.mksinst.cominvestor.mksinst.com, under in the heading Corporate Governance.Governance tab.

Audit Committee

The Audit Committee consists of Messrs. Anderson andMr. Beecher (Chair), Ms. Moloney and Ms. Mora. The Board of Directors has determined that each of the three current members of the Audit Committee is an “audit committee financial expert” as defined in applicable SEC regulations. Each member of the Audit Committee also meets the requirements for independence under applicable Nasdaq and SEC rules. The Audit Committee’s responsibilities include:

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The Audit Committee held five meetings in 2014.2017.

Compensation Committee

The Compensation Committee consists of Ms. Mora (Chair), Dr. Amon,Hanley and Mr. Anderson (Chair)Hess. Each member of the Compensation Committee meets the requirements for independence under applicable Nasdaq and Dr. Hanley.SEC rules. The Compensation Committee’s responsibilities include:

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The Compensation Committee held foursix meetings in 2014.2017. See the section below entitled “Executive Compensation — Compensation Discussion and Analysis” for further information about the role of the Compensation Committee and the scope of its activities.

Compensation Risk Assessment

Our Compensation Committee engaged its independent compensation consultant, Meridian, to conduct a risk assessment of our compensation programs and practices to understand if any risks exist that are reasonably likely to have a material adverse effect on our Company, and the results were reviewed by our Compensation Committee. Based on this assessment, our Compensation Committee concluded that our compensation programs and practices, as a whole, are appropriately structured and do not pose a material risk to our Company. Our compensation programs are intended to reward our executive officers and other employees for strong performance over the long-term, with consideration to short-term actions and results that strengthen and grow our Company. We believe our compensation programs provide the appropriate balance between short-term and long-term incentives, focusing on sustainable and profitable growth for our Company.

Compensation Committee Interlocks and Insider Participation

In 2017, the Compensation Committee was comprised of Ms. Mora (Chair), Dr. Hanley and Mr. Hess. None of the members of the Compensation Committee during 2017 were, at any time, officers or employees of MKS or our subsidiaries, and none of them had any relationship with us requiring disclosure under Item 404 of RegulationS-K under the Securities Exchange Act of 1934, as amended. None of our executive officers serves, or has served, as a member of the Board of Directors or Compensation Committee (or other committee serving an equivalent function) of any other entity which has one or more executive officers serving as a member of our Board of Directors or Compensation Committee.

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee consists of Dr. Amon, Mr. Chute (Chair), Dr. Hanley and Dr. Hanley.Ms. Moloney. Each member of the Nominating and Corporate Governance Committee meets the requirements for independence under applicable Nasdaq and SEC rules. The Nominating and Corporate Governance Committee’s responsibilities include:

The Nominating and Corporate Governance Committee held two meetings in 2014.2017.

For information relating to the nomination of directors, see “Director Candidates” below.

Audit Committee Financial Expert

The Board of Directors has determined that each of the three current members of the Audit Committee is an “audit committee financial expert” as defined in applicable SEC regulations.

Director Candidates

The Nominating and Corporate Governance Committee recommended to the Board of Directors that the director nominees be nominated by the Board of Directors for election as Class I directors. The process followed by the Nominating and Corporate Governance Committee to identify and evaluate director candidates includes Board assessments of each incumbent director nominee for the current year, requests to Board members and others for recommendations of potential candidates, meetings from time to time to evaluate biographical information and background material relating to potential candidates and interviews of selected candidates by the members of the Nominating and Corporate Governance Committee and the Board of Directors.

In considering whether to recommend any particular candidate for inclusion in the Board of Directors’ slate of recommended director nominees, the Nominating and Corporate Governance Committee applies the criteria attached to the Company’s Corporate Governance Guidelines. These criteria include the candidate’s integrity, business acumen, knowledge of our business and industry, age, tenure, experience, diligence, conflicts of interest and the ability to act in the interests of all shareholders. The Nominating and Corporate Governance Committee does not assign specific weights to particular criteria and no particular criterion is a prerequisite for each prospective nominee. Nominees shall not be discriminated against on the basis of race, religion, national origin, sex, sexual orientation, disability or any other basis proscribed by law. In considering director candidates, the Nominating and Corporate Governance Committee takes into account the value of diversity on the Board of Directors. While the Nominating and Corporate Governance Committee does not have a formal policy with

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respect to diversity, the Board of Directors and the Nominating and Corporate Governance Committee believe that it is essential that the members of the Board of Directors represent diverse viewpoints. In considering candidates for the Board of Directors, the Nominating and Corporate Governance Committee considers the entirety of each candidate’s credentials in the context of these standards. We believe that the backgrounds and qualifications of our directors, considered as a group, should provide a composite mix of experience, knowledge and abilities that will allow the Board of Directors to fulfill its responsibilities.

Shareholders may recommend individuals to the Nominating and Corporate Governance Committee for consideration as potential director candidates by submitting their names, together with appropriate biographical information and background materials and a statement as to whether the shareholder or group of shareholders making the recommendation has beneficially owned at least $2,000 in market value or 1% of our Common Stock, whichever is less, for at least a year as of the date such recommendation is made, to the Nominating and Corporate Governance Committee, in care of Kathleen F. Burke, Esq., Senior Vice President and General Counsel, MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, MA 01810. Assuming that appropriate biographical and background material has been provided on a timely basis, the Nominating and Corporate Governance Committee will evaluate shareholder-recommended candidates by following substantially the same process, and applying the same criteria, as it does in considering other candidates.

Shareholders also have the right under our Amended and RestatedBy-Laws to directly nominate director candidates, without any action or recommendation on the part of the Nominating and Corporate Governance Committee or the Board of Directors, by following the procedures set forth under the heading “Deadline for Submission of Shareholder Proposals for the 20152019 Annual Meeting” below.

CommunicationsDIRECTOR COMPENSATION

Cash Compensation

The following table summarizes cash compensation payable by us tonon-employee directors with respect to the period from ShareholdersJanuary 1, 2017 through December 31, 2017:

The

In October 2017, the Board of Directors, upon the recommendation of the Compensation Committee, approved several changes to thenon-employee director cash compensation program. The fees described in the table above will give appropriate attentionremain in effect through March 31, 2018, and the table below sets forth the cash compensation payable by us tonon-employee directors under the new cash compensation program effective as of April 1, 2018:

In addition, from time to time, the Board of Directors may establish special committees related to specific matters and may include a retainer for service on such special committees in its discretion.

Equity Compensation

Non-employee directors are eligible for awards under our 2014 Stock Incentive Plan, which is administered by the Compensation Committee. In 2017, under our director compensation program,non-employee directors received automatic grants of restricted stock units, or RSUs, on the date of the 2017 Annual Meeting of Shareholders, with a grant date value of $160,000, which RSUs shall vest in full on the day prior to the first annual meeting of shareholders following the date of grant (or if no such meeting is held within 13 months after

the date of grant, on the 13 month anniversary of the date of grant). In October 2017, the Board of Directors, upon the recommendation of the Compensation Committee, increased the value of the annual RSU grant to $170,000 for eachnon-employee director, effective on the date of the 2018 Annual Meeting of Shareholders.

If a newnon-employee director joins our Board of Directors after our annual meeting of shareholders but before January 1^st of the following year, he or she will be entitled to an initial RSU grant with a value equal to the annual RSU grant. In the event anon-employee director joins our Board of Directors during the period from January 1st through the date of that year’s annual meeting of shareholders, he or she will not be entitled to an initial RSU grant but will be entitled to the annual RSU grant on the date of the annual meeting of shareholders.

Mr. Bertucci

Mr. Bertucci resigned from his employment as our Executive Chairman effective December 31, 2006. At that time, he remained a Class III director and becamenon-executive Chairman of the Board of Directors. Pursuant to the terms of his employment agreement, Mr. Bertucci receives retiree medical benefits for life for himself and his spouse, which had a net present value of $304,917 as of December 31, 2017. The agreement requires that he make an annual contribution towards the retiree benefits of $1,500. Mr. Bertucci also receives a car allowance for life, which had a net present value of $191,952 as of December 31, 2017. Mr. Bertucci receives no other retirement benefits.

The following table summarizes compensation paid tonon-employee directors in 2017. Mr. Colella is excluded from the table because he is an executive officer, and his compensation is set forth in the Executive Compensation section below, under the heading “Executive Compensation Tables — Summary Compensation Table for 2017.”

Director Compensation Table for 2017

(4)

In connection with his retirement and pursuant to the terms of his previous employment agreement, Mr. Bertucci receives retiree medical benefits and a car allowance. The retiree medical benefits consist of benefits for life for himself and his spouse, towards which Mr. Bertucci makes an annual contribution of $1,500. We paid $14,774 for this benefit in 2017. We paid $14,898 for Mr. Bertucci’s car allowance in 2017.

SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

Section 16(a) of the Securities Exchange Act of 1934, as amended, requires executive officers, directors and shareholders who beneficially own more than 10% of our Common Stock to file initial reports of ownership on Form 3 and reports of changes in ownership on Form 4 with the SEC and any national securities exchange on which our securities are registered. Executive officers, directors and greater than 10% beneficial owners are required by the SEC’s regulations to furnish us with copies of all Section 16(a) forms they file.

Based solely on a review of the copies of such forms, and amendments thereto, furnished to us and written representations from the executive officers and directors, pursuant to Item 405 of RegulationS-K, we believe that all of our executive officers, directors and greater than 10% shareholders have complied with all applicable Section 16(a) filing requirements.

AUDIT AND FINANCIAL ACCOUNTING OVERSIGHT

Audit Committee Report

The Audit Committee of our Board of Directors has reviewed our audited financial statements for the year ended December 31, 2017 and discussed them with our management.

The Audit Committee has also received from, and discussed with, PricewaterhouseCoopers LLP, or PwC, our independent registered public accounting firm, various communications that areour registered public accounting firm is required to provide to the Audit Committee, including the matters required to be discussed by the Auditing Standard No. 16,Communications with Audit Committee.

The Audit Committee has received the written disclosures and the letter from our independent registered public accounting firm required by Independence Standards Board Standard No. 1 (Independence Standards Board Standard No. 1,Independence Discussions with Audit Committees), as adopted by the Public Company Accounting Oversight Board in Rule 3600T, and has discussed with our registered public accounting firm their independence.

Based on the review and discussions referred to above, the Audit Committee recommended to our Board of Directors that the audited financial statements be included in our Annual Report on Form10-K for the year ended December 31, 2017.

Respectfully submitted,

Gregory R. Beecher, Chair

Jacqueline F. Moloney

Elizabeth A. Mora

Principal Accountant Fees and Services

For the years ended December 31, 2017 and 2016, aggregate fees for professional services rendered by shareholders,our independent registered public accounting firm, PwC, in the following categories were as follows:

Audit Fees

Audit fees billed for both years consisted of fees for professional services rendered for: (i) the audit of our annual consolidated financial statements, (ii) statutory audits, (iii) the review of our consolidated financial statements included in our quarterly reports on Form10-Q, (iv) audit services related to other reports filed with the SEC, and will respond if appropriate. The Chair(v) the audit of our internal controls over financial reporting as required by the rules and regulations promulgated under Section 404 of the NominatingSarbanes-Oxley Act of 2002.

Audit-Related Fees

Audit-related fees for the year ended December 31, 2017 were for professional services associated with a new revenue recognition accounting standard. Audit-related fees for the year ended December 31, 2016 were for due diligence services performed in connection with our acquisition of Newport Corporation in April 2016.

Tax Fees

Tax Fees for the year ended December 31, 2017 were for services related to tax compliance, including the preparation of tax returns, and Corporate Governance Committee,tax planning and tax advice, including assistance with foreign operations and foreign tax audits. Tax Fees for the year ended December 31, 2016 were for services related to tax planning and tax advice, including assistance with foreign operations and foreign tax audits, and for services related to our acquisition of Newport Corporation.

All Other Fees

All Other Fees for the years ended December 31, 2017 and 2016 were for accounting research software.

In 2017 and 2016, all Audit Fees, Audit-Related Fees, Tax Fees and All Other Fees werepre-approved pursuant to the Audit Committee’spre-approval requirements, described below.

Pre-Approval Policy and Procedures

The Audit Committee’s charter sets forth the Audit Committee’s obligations relating to the approval of all audit andnon-audit services that are to be performed by our independent registered public accounting firm. The charter provides that we will not engage our independent registered public accounting firm to provide audit ornon-audit services unless the service ispre-approved by the Audit Committee. In addition, we will not engage any other accounting firm to provide audit services unless such services arepre-approved by the Audit Committee. It is the Audit Committee’s policy that with respect to services performed or to be performed by PwC in connection with each fiscal year of the Company, the annual fees fornon-audit services in such year shall not exceed one half of the aggregate fees payable to PwC for such year, without the prior express approval of the Audit Committee.

In connection with the assistanceforegoing, the Audit Committee may approve specific services in advance. In addition, from time to time, the Audit Committee maypre-approve specified types of services that are expected to be provided to us by our General Counsel,independent registered public accounting firm during the next 12 months. Any suchpre-approval of types of services is primarily responsible for monitoring communications from shareholders and for providing copies or summariesdetailed as to the other directors as he considers appropriate. Communications are forwardedparticular service or type of service to all directors if they relatebe provided and is also generally subject to important substantive matters and include suggestions or comments thata maximum dollar amount.

The Audit Committee has also delegated to the Chair of the Nominating and Corporate GovernanceAudit Committee considersthe authority to approve any audit ornon-audit services to be important forprovided to us by our independent registered public accounting firm. Any approval of services by the directorsChair of the Audit Committee pursuant to know. In general, communications relatingthis delegated authority is reported on at the next meeting of the Audit Committee.

The Audit Committee has considered and determined that the provision of thenon-audit services noted in the foregoing table is compatible with maintaining PwC’s independence.

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL

OWNERS AND MANAGEMENT

The following table sets forth certain information with respect to corporate governance and long-term corporate strategy are more likelythe beneficial ownership of our Common Stock by (i) each shareholder known to us to be forwardedthe beneficial owner of more than communications relating to ordinary business affairs, personal grievances5% of the outstanding shares of our Common Stock; (ii) the Named Executive Officers named in the Summary Compensation Table below; (iii) each of our current directors; and matters(iv) all of our directors and executive officers as to which we tend to receive repetitive or duplicative communications.

Shareholders who wish to send communications on any topica group. Unless otherwise indicated in the footnotes to the Boardtable, all equity amounts set forth in the table are as of Directors shouldJanuary 1, 2018; and the address such communications to the Boardfor each of Directors in care of Kathleen F. Burke, Esq., Vice Presidentour directors and General Counsel,executive officers is: c/o MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, MAMassachusetts 01810.

Code of Ethics

We have adopted a code of business conduct and ethics that applies to all of our directors, officers and employees (including the principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions), which is posted under the Investors tab on our website,www.mksinst.com under the heading Corporate Governance. We intend to disclose on our website any amendments to, or waivers for our executive officers or directors from, our code of business conduct and ethics.

Compensation Risk Assessment

We conducted a risk-assessment of our compensation programs and practices to understand if any risks exist that are reasonably likely to have a material adverse effect on our Company, and the results were reviewed by our Compensation Committee. Based on this assessment, our Compensation Committee concluded that our compensation programs and practices, as a whole, are appropriately structured and do not pose a material risk to our Company. Our compensation programs are intended to reward our executive officers and other employees for

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strong performance over the long-term, with consideration to short-term actions and results that strengthen and grow

To our Company. We believe our compensation programs provide the appropriate balance between short-term and long-term incentives, focusing on sustainable and profitable growth for our Company.

Compensation Committee Interlocks and Insider Participation

In 2014, the Compensation Committee was comprised of Dr. Amon, Mr. Anderson and Dr. Hanley. Noneknowledge, there are no voting trusts or similar arrangements among any of the membersforegoing persons or entities with respect to the voting of the Compensation Committee during 2014 were, at any time, officers or employeesshares of MKS or our subsidiaries, and none of them had any relationship with us requiring disclosure under Item 404 of Regulation S-K under the Securities Exchange Act of 1934, as amended. None of our executive officers serves, or has served, as a member of the Board of Directors or Compensation Committee (or other committee serving an equivalent function) of any other entity which has one or more executive officers serving as a member of our Board of Directors or Compensation Committee.Common Stock.

EXECUTIVE OFFICERS

The following is a brief summary of the background of each of our current executive officers, other than Mr. Colella, whose background is described under the heading “Directors” above:

Seth H. Bagshaw, Vice President, Chief Financial Officer and Treasurer, Age 55

Mr. Bagshaw has served as our Vice President and Chief Financial Officer since January 2010 and as Treasurer since March 2011. From March 2006 until January 2010, Mr. Bagshaw served as our Vice President and Corporate Controller. Prior to joining MKS, Mr. Bagshaw served as Vice President and Chief Financial Officer of Vette Corp., an integrated global supplier of thermal management systems from 2004 until 2006. From 1999 until 2004, Mr. Bagshaw served as Vice President and Corporate Controller of Varian Semiconductor Equipment Associates, Inc., a leading producer of ion implantation equipment used in the semiconductor manufacturing industry, and from 1998 until 1999, he served as Vice President and Chief Financial Officer of Palo Alto Products International, Inc., an industrial design, engineering and manufacturing company, until its acquisition by Flextronics International, Ltd. Prior to that, Mr. Bagshaw held several senior financial management positions at Waters Corporation, a developer of innovative analytical science solutions, most recently as Vice President and Chief Financial Officer of its Asia-Pacific region, and was a Senior Manager at PricewaterhouseCoopers LLP. Mr. Bagshaw has been a member of the Board of Directors of Associated Industries of Massachusetts, a non-profit state-wide employer advocacy and service organization, since 2010 and on its Audit Committee since 2014. Mr. Bagshaw is a Certified Public Accountant and has a B.S. in Business Administration from Boston University and an M.B.A. from Cornell

Name		Age		Background and Qualifications
John T.C. Lee, Senior Vice President and Chief Operating Officer		55		Dr. Lee has served as our Senior Vice President and Chief Operating Officer since November 2016. From January 2014 until October 2016, Dr. Lee served as our Senior Vice President of Business Units. From November 2012 until December 2013, Dr. Lee served as our Senior Vice President, Controls, HPS (our integrated process solutions business), and Pressure, Flow, Measurement and Control, or PFMC. From January 2011 to November 2012, he served as Senior Vice President, Controls and PFMC, and from October 2007 to January 2011, he served as our Group Vice President, Controls and Information Technology products. Prior to joining MKS, Dr. Lee served as the Managing Director of Factory Technology and Projects within the Solar Business Group at Applied Materials, Inc., a global leader providing processing equipment to the semiconductor and display markets, from February 2007 until October 2007. From 2002 until 2007, he served as General Manager of the Cleans Product Group and the Maydan Technology Center at Applied Materials. Prior to Applied Materials, Dr. Lee served from 1997 until 2002 as Research Director of the Silicon Fabrication Research Department at Lucent Technologies, Inc., a voice, data and video communications provider, and from 1991 until 1997 as a Member of the Technical Staff in the Plasma Processing Research Group within Bell Labs. Dr. Lee holds a B.S. from Princeton University and both an M.S.C.E.P. and a Ph.D. from the Massachusetts Institute of Technology, all in Chemical Engineering.
Brian C. Quirk, Senior Vice President of Global Operations		59		Mr. Quirk has served as our Senior Vice President of Global Operations since January 2014. From May 2006 until December 2013, Mr. Quirk served as our Vice President of Global Operations. Prior to joining MKS, Mr. Quirk served as Vice President of Global Operations and Supply Chain at Brooks Automation, Inc., a provider of automation, vacuum and instrumentation solutions. Prior to that, Mr. Quirk held executive leadership roles in global operations at Teradyne, Inc., a semiconductor and system level equipment provider, GenRad, Inc. (acquired by Teradyne, Inc.), a manufacturer of electronic automatic test equipment and related software, and Stratus Computer, Inc. (now known as Stratus Technologies, Inc.), a producer of fault tolerant computer servers. Mr. Quirk has a B.S. in Business Management from Bentley University and an M.B.A. from Suffolk University.
Dennis L. Werth, Senior Vice President of Business Units		63		Mr. Werth has served as our Senior Vice President of Business Units since MKS acquired Newport Corporation in April 2016. Mr. Werth joined Newport Corporation in February 2005, most recently serving as Senior Vice President and General Manager of the Photonics Group from January 2013 until April 2016, and previously as Vice President of the Precision Components and Systems Business. Prior to joining Newport Corporation, Mr. Werth served as Senior Director and General Manager of Oriel Instruments, a supplier of products for the making and measuring of light, which was later acquired by Newport Corporation, from January 2004 until February 2005. Prior to joining Oriel, Mr. Werth was the Chief Operating Officer of Isowave, a supplier of advanced optical materials and fiber optic components, from July 2001 to December 2003. From November 1996 to June 2001, he served as

John R. Abrams, Senior Vice President of Global Sales, Age 62

Mr. Abrams has served as our Senior Vice President of Global Sales since January 2014. From October 2011 until December 2013, Mr. Abrams served as our Vice President of U.S. Sales. Prior to joining MKS, Mr. Abrams served as a business development consultant to AIRxpert Systems, Inc., an environmental information technology company, from October 2010 to October 2011. From February 2009 until September 2010, Mr. Abrams served as a Senior Marketing Manager for Varian, Inc., a maker of scientific equipment which was acquired by Agilent Technologies, Inc., a maker of measurement tools, in May 2010. From March 1997 until November 2008, Mr. Abrams served in several roles, most recently as Vice President of Global Sales, at Brooks Automation, Inc., a provider of automation vacuum and instrumentation solutions. Mr. Abrams received a B.S. in Biological Sciences from Lowell Technological Institute and an M.B.A. from Boston University.

John T.C. Lee, Senior Vice President of Business Units, Age 52

Dr. Lee has served as our Senior Vice President of Business Units since January 2014. From November 2012 until December 2013, Dr. Lee served as our Senior Vice President, Controls, HPS and PFMC. From January 2011 to November 2012, Dr. Lee served as Senior Vice President, Controls and PFMC. From

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October 2007 to January 2011, Dr. Lee served as our Group Vice President, CIT Products. Prior to joining MKS, Dr. Lee served as the Managing Director of Factory Technology and Projects within the Solar Business Group at Applied Materials, Inc., a global leader in nanomanufacturing and technology solutions, from February 2007 until October 2007. From 2002 until 2007, he served as General Manager of the Cleans Product Group and the Maydan Technology Center at Applied Materials. Prior to Applied Materials, Dr. Lee served from 1997 until 2002 as the Research Director of the Silicon Fabrication Research Department at Lucent Technologies, Inc., a voice, data and video communications provider, and from 1991 until 1997 as a Member of the Technical Staff in the Plasma Processing Research Group within Bell Labs. Dr. Lee holds a B.S. from Princeton University and both an M.S.C.E.P. and Ph.D. from the Massachusetts Institute of Technology, all in Chemical Engineering.

Brian C. Quirk, Senior Vice President of Global Operations, Age 56

Mr. Quirk has served as our Senior Vice President of Global Operations since January 2014. From May 2006 until December 2013, Mr. Quirk served as our Vice President of Global Operations. Prior to joining MKS, Mr. Quirk served as Vice President of Global Operations and Supply Chain at Brooks Automation, Inc., a provider of automation vacuum and instrumentation solutions. Prior to that, Mr. Quirk held executive leadership roles in global operations at Teradyne, Inc., a semiconductor and system level equipment provider, GenRad, Inc. (acquired by Teradyne, Inc.) and Stratus Computer, Inc. (now known as Stratus Technologies, Inc.), a producer of fault tolerant computer servers. Mr. Quirk has a B.S. in Business Management from Bentley University and an M.B.A. from Suffolk University.

Name		Age		Background and Qualifications
				Business Segment Leader, Electronic Components and Electronic Article Surveillance, at Allied Signal, Inc., a diversified manufacturer, which merged with Honeywell, Inc. in 1999. Prior to joining Allied Signal, from May 1985 to June 1996, Mr. Werth held various management positions of increasing responsibility at Amoco Corporation, most recently serving as Vice President of Marketing and Business Development of that company’s ATx Telecom Systems, Inc. subsidiary (formerly Amoco Laser Company, which Mr. Werthco-founded in 1987 and which was sold to Scientific Atlanta in June 1996). Mr. Werth holds a B.S. in Engineering from the University of Illinois, an M.S. in Engineering from Ohio State University and an M.B.A. from Eastern Michigan University.

Our executive officers are appointed by the Board of Directors on an annual basis and serve until their successors are duly appointed and qualified. There are no family relationships among any of our executive officers or directors.

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EXECUTIVE COMPENSATION

Compensation Discussion and Analysis

Introduction

The purpose of this section of our proxy statement is to provide an overview of our executive compensation program, our compensation philosophy and objectives, and the material decisions we made with respect to each element of our executive compensation program. Throughout this proxy statement, we refer to the following “Named Executive Officers:”Officers”:

Following this Compensation Discussion and Analysis, you will find a series of tables containing specific information about the compensation earned or paid in 20142017 to our Named Executive Officers. All of our executive officers are also our Named Executive Officers.

Executive Summary

Founded in 1961, weOur Business

We are a global provider of instruments, subsystems and process control solutions that measure, control,monitor, deliver, analyze, power monitor and analyzecontrol critical parameters of advanced manufacturing processes to improve process performance and productivity. 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, RF & DC 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, software, service and maintenance, installation services and training. Our primary served markets include semiconductor capital equipment, general industrial, life sciences and research.

Among our strategic goals is the achievement ofCompany Performance in 2017 and Financial Highlights

2017 was another exceptional year for MKS as revenue and earnings per share, or EPS, both set new Company records. Four years ago, we set a strategy around sustainable and profitable growth and in 2014 we made excellent progress toward this goal as evidenced bygrowth. One of the tenets of our strategy was to augment our strong financial and operational performance. Revenue for 2014 increased 17% compared to 2013 and non-GAAP (generally accepted accounting principles in the U.S.) net earnings more than doubled.semiconductor market portfolio with acquisitions that broadened our addressable markets. In addition,April 2016, we deployed over $140 million in capital during 2014 forcompleted the acquisition of Granville-PhillipsNewport Corporation, or Newport, a global leader in May 2014,lasers, optics and photonics. This acquisition not only increased our addressable share in our core semiconductor market, but has also given us critical mass to expand into other adjacent, technology intensive and growing markets, including industrial technologies, life and health sciences, and research and defense. Our ability to successfully integrate Newport into the repurchaseexisting MKS business helped us deliver the 2017 results.

We also continued to make significant progress addressing our customers’ technical requirements. Investments in “technical localization” – providing technical expertise and developing customer relationships close to our customers has been an effective method to rapidly identify and solve our customers’ most complex problems. This strategy has been a significant contributor to our success in the Asia region.

In addition, MKS accomplished the following in 2017:

2017 Compensation Outcomes

Under our performance-basedOur executive compensation program our 2014 performance-based variable cash and equity compensation foris designed to reward our Named Executive Officers werefor performance and to align their interests with those of our shareholders. As a result of our strong financial results in 2017, our Named Executive Officers received 200% of their target variable cash compensation tied to our Company’s non-GAAP operating income and 121% of their target performance-based equity compensation tied tonon-GAAP cash flow from operations, respectively.operations. We believe these financial performance metrics are important to our shareholders because each is an indicator of how well we manage the operations and capital of our Company. As a resultThe Company performance portion of our strong financial results in 2014,variable cash compensation for all of our executive officers received 124%other than Mr. Werth was tied to the financial performance of our Company as a whole. The Company performance portion of variable cash compensation for Mr. Werth, who heads up our Light and Motion Division, was tied to the financial performance of our Light and Motion Division.

In 2017, our variable cash incentive compensation for all of our Named Executive Officers, other than our Chief Executive Officer, also included an individual performance component with an assigned weighting of 20% of total target variable cash compensation. The Named Executive Officers who were assigned individual performance goals achieved, on average, 188% of the portion of their target variable cash compensation and 150% of their target performance-based restricted stock units.tied to individual performance. Our Compensation Committee did not assign an individual performance component to our Chief Executive Officer’s cash incentive compensation because it believes our Chief Executive Officer should be held accountable for the Company’s overall performance.

OurWhen our Compensation Committee set 2017 executive compensation program is designed to reward our executive officers for performance and to align their interests with those of our shareholders. In 2014,in early 2017, long-term equity incentive compensation comprised 54%64% of total target compensation for our Chief Executive Officer and 41%51% of total target compensation, on average, for our other Named Executive Officers. Total target compensation is defined as the sum of base salary, target annual cash incentive compensation and target long-term equity incentive compensation. By making equity a substantial component of executive officer compensation, we align our executive officers’ long-term interests with those of our shareholders. Fifty percentAlso, at least 50% of each Named Executive Officer’s target long-term equity incentive compensation is based on a measure of Company performance as measured by annual adjusted cash flow from operations for the year of grant.performance.

Our annual cash incentive plan is designed to complement our long-term equity incentive plan by focusing on our Company’s annual financial performance as measured by adjusted operating income. In 2014,2017, our target annual cash incentive compensation comprised 23%18% of total target compensation for our Chief Executive Officer and 24%22% of total target compensation, on average, for our other Named Executive Officers.

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In 2014,2017, base salary accounted for 23%18% of total target compensation for our Chief Executive Officer and 35%27% of total target compensation, on average, for our other Named Executive Officers. This means thatIn 2017, our Chief Executive Officer had 77%82% of his total target compensation opportunity tied to annual and long-term incentive compensation and our other Named Executive Officers, on average, had 65%73% of their total target compensation opportunity tied to annual and long-term incentive compensation.

The following charts showConsideration of 2017 Advisory Vote on Executive Compensation

At our 2017 Annual Meeting of Shareholders, held on May 10, 2017, we submitted to our shareholders an advisory vote on executive compensation. Although annual advisory“say-on-pay” votes arenon-binding, our Compensation Committee has considered, and will continue to consider, the componentsoutcome of total targetthis vote each year when making compensation and total actual compensationdecisions for our ChiefNamed Executive Officer andOfficers. At the 2017 Annual Meeting, our othershareholders overwhelmingly approved the compensation of our Named Executive Officers, as a group for calendar year 2014.with approximately 96% of the votes cast voting in favor of the“say-on-pay” proposal.

The Compensation Committee considered the results of the 2017say-on-pay vote, and based upon the strong shareholder support, does not believe that our executive compensation program requires material changes. The Compensation Committee will continue to consider the views of our shareholders in connection with our executive compensation program and will consider changes based upon evolving best practices, market compensation information and changing regulatory requirements. The Compensation Committee believes that the 2017 shareholder vote was an endorsement of our compensation and the pay decisions made in relation to our performance.

Compensation Philosophy and Objectives

The primary objective of our executive compensation program is to attract, retain and motivate the critical talent that is required to execute our business strategy and lead us to achieve our long-term growth and earnings goals. This section summarizes our compensation philosophy and objectives relating to our Named Executive Officers.

At our 2014 Annual Meeting of Shareholders, held on May 5, 2014 (the “2014 Annual Meeting”), we submitted to our shareholders an advisory vote on executive compensation. Although this annual advisory “say-on-pay” vote is non-binding, the Compensation Committee has considered, and will continue to consider, the outcome of this vote each year when making compensation decisions for our Named Executive Officers. At the 2014 Annual Meeting, our shareholders overwhelmingly approved the compensation of our Named Executive Officers, with approximately 95.9% of the votes cast voting in favor of the “say-on-pay” proposal.

The Compensation Committee considered the results of the 2014 say-on-pay vote, and based upon the strong shareholder support, does not believe that our executive compensation program requires material changes. The Compensation Committee will continue to consider the views of our shareholders in connection with our

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executive compensation program and will consider changes based upon evolving best practices, market compensation information and changing regulatory requirements. The Compensation Committee believes that the 2014 shareholder vote was an endorsement of our compensation and the pay decisions made in relation to our performance.

Our executive compensation program is guided by the following principles:

Elements of Compensation

The following summarizes the compensation elements for our Named Executive Officers. We target each of the various compensation elements, including base salary, annual cash incentive compensation, and long-term equity incentive compensation, to be in thewithin a competitive range of the competitivearound median levels for the individual position in the market. However, this is merely one factor that the Compensation Committee considers and we do not set any specific element or total compensation exactly to the median.median and, in certain cases, we will and do pay total compensation closer to the 25th and 75th percentiles when appropriate. In considering the compensation of an executive officerour Named Executive Officers relative to the market, we also look qualitatively at the individual’s overall performance, tenure and potential with MKS. Currently, all of our Named Executive Officers are paid within the competitive range of our peer group.

Base Salary

Base salaries are designed to provide executives with a level of predictability and stability with respect to a portion of their total compensation package. BecauseBase salaries are a relatively small component in the overall pay packages of the highly cyclical nature of our business, we have from

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time to time imposed temporary salary reductions. For 2014, our Compensation Committee approved a salary increase of 20% for our Chief Executive Officer and a salary increase of 14% for each of our other Named Executive Officers who were alsobecause we believe the significant majority of executive officers in 2013. The 20% salary increase for our Chief Executive Officer reflects his promotion to his new role in January 2014compensation should be variable and his actual job performance, as well as relevant benchmarking data provided by our independent compensation consultant.

Annual Cash Incentive Planbased on performance.

Our annual cash incentive plancompensation program provides a short-term incentive to reward management for reaching our annual earnings goalgoals and, in certain cases, individual performance objectives, and to reinforce ourpay-for-performance philosophy. We believe that our planprogram provides significant incentive for our executive officersNamed Executive Officers to exceed our financial goals. Under our plan, each executive officer, other than Mr. Abrams who is paid pursuant to a commission plan described below, is eligible to receive a performance bonus based on a specified percentage of eligible earnings, which is defined as eligible W-2 earnings received during the plan period (i.e., base salary, including regular, holiday, vacation and sick pay, but excluding bonus payments). Bonus payouts are based entirely on a corporate financial performance objective, which we believe eliminates complexity, fosters cooperative effort and closely aligns the interests of all our executive officers with those of our shareholders. In 2014, each executive officer was eligible to receive 60% of his target bonus if the minimum threshold was achieved. If we had achieved our target results, each executive officer would have been eligible to receive 100% of his target bonus, up to a maximum of 200% for achievement in excess of the target results, with incremental payouts for performance between these levels. In the event the minimum threshold for the corporate financial performance objective was not met, but would have been met but for the payment of the bonuses under the annual cash incentive plan, then in such case a pro rata portion of the bonus would be paid to each executive officer, but only to the extent that the corporate financial performance objective after such payment was no less than the minimum corporate financial performance objective.

While our plan reflects our typical strategy with respect to annual cash incentive bonuses, we do, from time to time, customize our plan to take into account special circumstances. We expect any such variations to the plan to occur only in unusual circumstances and we did not customize it in 2014.

The average bonus payout for all Named Executive Officers in the past ten years through 2014 was approximately 96% of target bonus levels. While the Company endeavors to set reasonable but challenging targets for the plan each year, consistent achievement is particularly challenging in the semiconductor industry, which is subject to wide and often unpredictable demand shifts.

In 2014, payouts under the annual cash incentive plan were calculated by multiplying a Named Executive Officer’s “Target Bonus Amount” by the “Corporate Performance Multiplier,” each as discussed below. Target Bonus Amount is the amount determined by multiplying each Named Executive Officer’s eligible earnings in 2014 by the Target Bonus Percentages listed below.

In 2014, the Corporate Performance Multiplier, which is a percentage, was based upon our achievement of adjusted operating income after bonus and excluding special items. Participants would not receive any portion of their Target Bonus Amount if such adjusted operating income was less than the minimum threshold of $68.7 million. The Corporate Performance Multiplier would be 60% of a Participant’s Target Bonus Amount if such adjusted operating income was $68.7 million, and would be the maximum 200% if such adjusted operating income was $229.2 million or more, with incremental payments for achievement in between. In 2014, because our adjusted operating income after bonus and excluding special items was $142 million, participants received 124% of their Target Bonus Amounts.

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Mr. Abrams’ Cash Incentive Compensation

Mr. Abrams, our Senior Vice President of Global Sales, does not participate in our annual cash incentive plan. Instead, our Compensation Committee ties Mr. Abrams’ annual cash incentive compensation to sales commissions based on bookings. Our Compensation Committee believes this will incentivize Mr. Abrams to drive corporate sales team objectives more directly than our annual cash incentive plan. For 2014, Mr. Abrams commission-based cash incentive target was set at 70% of his base salary based on a bookings goal of $758.3 million. Mr. Abrams achieved 110% of his commission target based on bookings of $782.1 million. For details regarding the amount paid to Mr. Abrams as sales commissions, see Footnote 2 to the Summary Compensation Table for 2014.

Long-Term Equity Incentive Compensation

We provide our executive officersNamed Executive Officers with long-term equity incentive compensation in the form of restricted stock units, or RSUs, approximately half of which are performance-based, in order to:

The following charts show the components of total target compensation for our Chief Executive Officer and our other Named Executive Officers as a group for calendar year 2017.

When the Compensation Committee met in October 2016 to review peer companies to be used to determine 2017 executive compensation, no changes were made to the list of peer companies used to determine 2016 executive compensation. These peer companies had been selected in May 2016, following the closing of our acquisition of Newport, based on similar industry, market capitalization and revenue, with a revenue range relative to our projected revenue of between 0.4 times and 2.0 times. The Compensation Committee engaged its independent compensation consultant, Meridian, to prepare a competitive compensation analysis for each of our executives on aposition-by-position basis based on estimated revenue and market capitalization of the combined company of $1.4 billion and$2.5-$3.0 billion, respectively. Publicly available compensation data from the following comparable peer companies was used in determining executive compensation for 2017:

Our Compensation Committee also considered size and industry-appropriate broad survey data from the 2017 Radford Global Technology Survey.

Our executive compensation program is guided by the following principles:

Elements of Compensation

The following summarizes the compensation elements for our Named Executive Officers:

Base Salary

When our Compensation Committee set 2017 annual executive compensation in early 2017, it approved a salary increase of approximately 3% for each of our Chief Executive Officer, Chief Financial Officer and Chief Operating Officer, and a salary increase of approximately 12% for each of our Senior Vice President of Global Sales and Service and our Senior Vice President of Business Units. These increases were based on the compensation data collected from our peer group.

Annual Cash Incentive Compensation

Our annual cash incentive compensation program consists of our shareholder-approved executive cash incentive plan, which is called the 162(m) Plan, and our annual cash incentive plan.

Pursuant to the terms of the 162(m) Plan, our Compensation Committee established an “umbrella” formula to determine aggregate funding for the plan based on the achievement of a specific,pre-determined Company financial performance goal. Under the umbrella formula, each Named Executive Officer was allocated a share of an incentive pool based on our adjusted operating income for the 2017 fiscal year (defined as GAAP operating income adjusted for restructuring charges, acquisition or divestiture related costs and the effect of acquisitions and divestitures). The Compensation Committee exercises negative discretion from this 162(m) pool by applying the goals of our annual cash incentive plan as described below.

Under our annual cash incentive plan, each Named Executive Officer was eligible to receive a performance bonus based on a specified percentage of eligible earnings, which is defined as eligibleW-2 earnings received during the 2017 calendar year (i.e., base salary, including regular, holiday, vacation and sick pay, but excluding bonus payments). Bonus payouts in 2017 were based 80% on a Company financial performance objective and 20% on individual performance objectives for all Named Executive Officers other than our Chief Executive Officer, whose annual executive bonus was based entirely on Company financial performance.

In 2017, each Named Executive Officer was eligible to receive 50% of his target bonus attributable to the Company performance objective if the minimum threshold was achieved. If we had achieved our target results, each such Named Executive Officer would have been eligible to receive 100% of his target bonus attributable to

the Company performance objective, up to a maximum of 200% for achievement in excess of the target results, with proportional payouts for performance between these levels. In the event the minimum threshold for the Company financial performance objective was not met, but would have been met but for the payment of these bonuses, then in such case a pro rata portion of the bonus would be paid to each such Named Executive Officer, but only to the extent that the Company financial performance objective after such payment was no less than the minimum Company financial performance objective.

In 2017, payouts for Company financial performance under the annual cash incentive plan were determined by multiplying a Named Executive Officer’s “Target Bonus Amount” by the “Company Performance Multiplier,” each as discussed below. Target Bonus Amount is the amount determined by multiplying each Named Executive Officer’s eligible earnings in 2017 by the Target Bonus Percentages determined by our Compensation Committee each year. When our Compensation Committee set 2017 annual executive compensation in early 2017, it did not approve any increases to Target Bonus Percentages for our Named Executive Officers.

Listed below is the 2017 Target Bonus Percentage for each Named Executive Officer.

In 2017, the Company Performance Multiplier, which is a percentage, was based upon our achievement of adjusted operating income after bonus and excluding special items. Participants, other than Mr. Werth, would not receive any portion of their Target Bonus Amount tied to Company financial performance if such adjusted operating income (before the calculation of bonus) was less than the minimum threshold of $175.0 million. The Company Performance Multiplier would be 50% of a Participant’s Target Bonus Amount if such adjusted operating income was $175.0 million, would be 100% if such adjusted operating income was $245.2 million, and would be the maximum 200% if such adjusted operating income was $367.9 million or more, with proportional payments for achievement in between these levels. In 2017, because our adjusted operating income, after bonus and excluding restructuring charges, acquisition and divestiture related costs and the effect of acquisitions and divestitures, was $429.2 million, participants were eligible to receive 200% of their Target Bonus Amounts tied to Company financial performance under this formula. For Mr. Werth, the 2017 Company Performance Multiplier was based on the Light and Motion Division’s achievement of adjusted operating income after bonus and excluding special items. Mr. Werth would not receive any portion of his Target Bonus if such adjusted operating income was less than the minimum threshold of $51.2 million. The Company Performance Multiplier would be 50% of Mr. Werth’s Target Bonus Amount if such adjusted operating income was $51.2 million, would be 100% if such adjusted operating income was $71.8 million, and would be the maximum 200% if such adjusted operating income was $107.7 million or more, with proportional payments for achievement in between. In 2017, because the Light and Motion Division’s adjusted operating income, after bonus and excluding restructuring charges, acquisition and divestiture related costs and the effect of acquisitions and divestitures, was $116.4 million, Mr. Werth was eligible to receive 200% of his Target Bonus Amount under this formula.

In 2017, individual performance was measured using specific “management by objective” goals, or MBOs, that were aligned to our strategic objectives and priorities and each Named Executive Officer’s business unit or function. Our Chief Executive Officer developed the MBOs for his direct reports with a focus on the measurable accomplishments in their individual areas of responsibility that will benefit our shareholders over the long term.

Listed below is a summary of each Named Executive Officer’s performance against his 2017 MBOs.

2017 Named Executive Officer MBOs under Annual Cash Incentive Plan (20% of Target Cash Incentive)
Name		Management by Objective Goals		Weight		Results		Achievement Level
Dennis L. Werth		Improve 2017 Operating Model		25%		Achieved 18% growth in sales and 67% growth in operating income in our Light and Motion Division in 2017		200%
		Achieve Strategic Planning Goals		25%		Achieved strategic planning goals relating to centralization of business functions within Light and Motion Division		100%
		Drive New Product Releases		25%		Drove the release of new products		100%
		Achieve Integration and Synergy Objectives		25%		Increased cost synergy target in 2017 related to the acquisition of Newport Corporation and achieved revised cost synergy target ahead of schedule		200%

Listed below are our Chief Executive Officer’s and other Named Executive Officers’ earned cash bonus payouts based on the achievement of the Company performance metric weighted at 100% of target for Mr. Colella, and 80% of target and the individual performance objectives weighted at 20% of target for the other Named Executive Officers.

For 2017, our incentive pool was funded based on 20% of our adjusted operating income for the 2017 fiscal year (defined as GAAP operating income (operating income prepared in accordance with U.S. generally accepted accounting principles, or GAAP) adjusted for restructuring charges, acquisition or divestiture related costs and the effect of acquisitions and divestitures), but not to exceed $10 million. Mr. Colella was allocated 30% of the incentive pool and the other Named Executive Officers were each allocated 14% of the pool. Our adjusted operating income for 2017 was $336.0 million, which resulted in a bonus pool of $10 million under the terms of the 162(m) Plan, of which $4.7 million was distributed to our Named Executive Officers as described above.

For 2018, the Compensation Committee made the following two changes to our annual cash incentive program:

With the exception of these two changes, the design of our 2018 annual cash incentive program is similar to 2017. For all Named Executive Officers other than Mr. Werth, Company performance will be measured using the same financial metric as in previous years –non-GAAP operating income after bonus and excluding special items. For Mr. Werth, Company performance will continue to be measured using Light and Motion Division’s achievement ofnon-GAAP operating income after bonus and excluding special items.

Our Compensation Committee has the authority to make other cash bonus awards to our Named Executive Officers as it deems appropriate. No other cash bonus awards were made to our Named Executive Officers in 2017.

Long-Term Equity Incentive Compensation

When our Compensation Committee set 2017 annual executive compensation in early 2017, it awarded the following time-based and performance-based RSUs to our Chief Executive Officer and our other Named Executive Officers. These RSUs vest in three equal annual installments. The performance-based RSUs are subject to aone-year performance metric described below.

With respect to performance-based RSUs, our goal is to select a corporateCompany financial performance metric that best aligns with our corporateCompany objectives. For example,Recently, including in 2009, due to the unusual economic conditions at that time,2017, our corporate financial performance metric was the achievement of an annual corporate cash break-even level to motivate executives to control costs during the downturn. More typically, and in 2014, our corporateCompany financial performance metric for performance-based RSUs washas been adjusted cash flow from operations (net(defined as net income plus depreciation, amortization andnon-cash stock-based compensation and excluding special items)items set forth in Section 9(c)(i) through (xiv) of our 2014 Stock Incentive Plan) set at varying revenue levels. We believe this financial metric is an accurateappropriate indicator of how well we manage the operations of our Company.

We use RSUs as our form of equity incentive compensation because we believe RSUs help to ensure that our executive officers’ interests are aligned with our shareholdersshareholders’ in both a rising and a declining stock market. We believe RSUs are preferable to options, which have a relatively high accounting cost as compared to their potential value to the executive officer, and are preferable to restricted stock, which gives the executive officer voting and dividend rights prior to full vesting. BecauseAlso, because RSUs are worth more than options on the date of grant, we are able to grant fewer of them than options, resulting in less dilution to shareholders’ holdings.

In 2014,2017, our Named Executive Officers would have forfeited all of their performance-based RSUs if our adjusted cash flow from operations was less than $62.0$148.0 million at a revenue level of $650 million,$1.25 billion, or if such

cash flow was less than $160.4$355.5 million at a revenue level of $1.0$2.0 billion (with intermediate adjusted cash flow minimum thresholds at different revenue levels in between). However, if we did achieve these adjusted operating cash flow threshold levels at the respective revenue levels identified, our Named Executive Officers would receive 50% of their target performance-based RSUs. If our adjusted cash flow from operations was $83.7 millionat or more at a revenue level of $650 million, or was greater than $216.6above $199.7 million at a revenue level of $1.0$1.25 billion, or was at or above $479.9 million at a revenue level of $2.0 billion (with incrementalproportional thresholds in between), then our Named Executive Officers would receive the maximum of 150% of their target performance-based RSUs. IncrementalProportional payments would be made for adjusted cash flow achievements between the minimum and maximum levels. In 2014,2017, because our revenue was $1.9 billion and our adjusted cash flow was $125.8 million at a revenue level of $765$413.9 million, after removingexcluding restructuring charges, acquisition and divestiture related costs and the impacteffect of acquisitions and divestitures, and the effect of changes in tax laws, our Named Executive Officers received 150%121% of their target performance-based RSUs. These performance-based RSUs, along with the time-based RSUs granted to our Named Executive Officers, vest in equal annual installments over three years from the original date of grant.

It is our practice to make an initial equity-based grant to all executive officersof our Named Executive Officers at the time they commence employment, in an amount that is consistent with amounts granted to other executive officers in the industry at similar

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levels of seniority. In addition, we typically make an annual grant of equity-based compensation to executive officersour Named Executive Officers during the first fiscal quarter of each year. Discretionary equity-based grants may be made throughout the year to provide an incentive to achieve a specific goal or to reward a significant achievement. Our Compensation Committee made one discretionary award in February 2017 to Dennis Werth. He was awarded additional time-based RSUs in February 2017 equal to 7% of his target performance-based equity compensation awarded in 2016, due to his strong performance following the Newport acquisition. These RSUs vest in three equal annual installments beginning February 15, 2018. Also in 2017, our Compensation Committee accelerated the vesting of a special performance-based RSU award granted in June 2016 to each of Messrs. Colella, Bagshaw, Abrams and Lee tied to the achievement of cost synergies from the Newport acquisition. These awards were scheduled to vest in two annual installments in June 2017 and 2018, provided specified cost synergies were achieved on each measurement date. Our Compensation Committee accelerated the vesting of these awards in full on May 11, 2017 after determining that more than 100% of the cost synergies had already been achieved.

Supplemental Retirement Benefits

We provide supplemental retirement benefits, including supplemental lifetime retiree medical benefits, to our current Chief Executive Officer and President, Mr. Colella, or, in the event of his death, to his spouse. These supplemental retirement benefits were designed to reward Mr. Colella’s long service with us and to serve as a significant incentive for Mr. Colella to remain with us because these benefits are contingentwill vest in full upon himMr. Colella maintaining his employment with us until age 62, with specified exceptions. Mr. Colella, who first joined theour Company in 1983 as our Materials Planning and Logistics Manager, served in numerous capacities over the course of the next thirty plus years to ultimately become our Chief Executive Officer in addition to his role as President, on January 1, 2014.and President.

Since 2011, it has been our policy not to offer these types of retirement benefits to other executive officers in the future.Named Executive Officers. While these benefits were attractive elements to retain certain of our most senior executive officers historically, the elimination of these benefits more closely meets our objective to align executive compensation with Company financial performance.

Newport Deferred Compensation Plan

In connection with the Newport acquisition in April 2016, we assumed Newport’s Deferred Compensation Plan. Historically, Mr. Werth has made elections to defer a portion of his compensation into this plan. He did not make such an election in 2015 for 2016 compensation. In 2016, Newport employees who were eligible to participate in the plan were not permitted to make an election for the deferral of any of their salaries in 2017 but did have the opportunity to make an election to defer their 2017 annual incentive compensation to the extent earned and paid in 2018. Mr. Werth elected to defer 100% of his 2017 annual incentive compensation. No further elections will be permitted under this plan.

Perquisites

We offer certain perquisites to our Named Executive Officers to allow executives to focus on corporate strategy and enhancing shareholder value and to provide competitive pay packages. Examples of theseThese perquisites areinclude car payments, company paid health cost reimbursements and life insurance, reimbursement of certainout-of-pocket healthcare costs, golf club memberships.memberships, financial planning benefits and executive physicals. We believe offering these benefits is important to maintaining a competitive position in attracting and retaining key personnel and these benefits are consistent with market practices.

Severance andChange-in-Control Provisions

Each of our Named Executive Officers is entitled to certain payments and benefits in the event his employment terminates under specified circumstances.circumstances as described in the applicable agreement. In exchange for these payments and benefits, each Named Executive Officer, other than Mr. Werth, whose agreement is governed by California law, is restricted from competing with the Company during and following thehis termination of employment for a certain period of time.twelve-month period. In addition, RSU agreements with our Named Executive Officers, or in Mr. Werth’s case, solely with respect to certain of his RSU agreements, provide for acceleration of vesting in the event the executive’s employment is terminated without cause or the executive resigns for good reason within 24 months after achange-in-control. The severance andchange-in-control provisions are designed to be competitive in the marketplace, to provide security for our Named Executive Officers in the event that we are acquired and his respective position is impacted and to provide an incentive for the Named Executive Officer to stay with us through such achange-in-control event. These provisions are also intended to protect us from competitive harm, by compensating our Named Executive Officers for agreeing to substantialnon-compete provisions after employment termination. See “Executive Compensation Tables — Potential Payments Upon Termination or Change in Control”Change-in-Control” for more information about these agreements.

Compensation of our Chief Executive Officer

We entered into an employment agreement with Mr. Colella was promoted toupon his becoming Chief Executive Officer and President in addition to his role as President, effective January 1, 2014. In connection with Mr. Colella’s promotion, MKS entered into a new employment agreement with him, also effective as of January 1, 2014. The terms of Mr. Colella’s new employment agreement reflect his new role as the leader of our Company and the experience he bringsbrought to the position having served more than 3230 years at MKS. We believe the terms of Mr. Colella’s new employment agreement reflect the Company’s compensation philosophy and are consistent with the terms of the employment agreement we had entered into with our previous Chief Executive Officer. For a detailed discussion of the material terms of Mr. Colella’s new employment agreement, please see the summary of the agreement in the section of the proxy statement entitled “Executive Compensation Tables — Potential Payments Upon Termination or Change in Control.Change-in-Control.”

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Compensation of our Other Named Executive Officers

We have entered into employment agreements with each of our other Named Executive Officers. For a detailed discussion of the material terms of these executive employment agreements, please see the summary of the agreements in the section of the proxy statement entitled “Executive Compensation—Compensation Tables — Potential Payments Upon Termination or Change in Control.Change-in-Control.”

Compensation Consultant; Market ComparisonConsultant

We periodically engage a compensation consultant to serve as an independent advisor to the Compensation Committee regarding compensation for our directors and our executive officers. The Compensation Committee utilizes the compensation consultant in the following ways:

From 2007 to

Since October 2014, the Compensation Committee has engaged Radford, an Aon Hewitt Company (“Radford”),Meridian as its compensation consultant. The Compensation Committee determined that the engagement of RadfordMeridian as a compensation consultant did not raise any conflicts of interest with MKS. In the fall of 2014, our Compensation Committee sought proposals from other compensation consultants and, in October 2014, selected Meridian Compensation Partners, LLC as its new compensation consultant, to provide executive officer compensation advice beginning in 2015.

When determining executive compensation for 2014, the Compensation Committee, with the assistance of Radford, reviewed size and industry-appropriate broad survey data from The 2013 Radford Global Technology Compensation Survey, as well as publicly available compensation data from the following comparable peer companies:

These peer companies were selected because they compete in the semiconductor industry and are similar to MKS in terms of revenues and market capitalization.

In October 2013, the Compensation Committee engaged Radford to prepare a competitive compensation analysis for each of our executives on a position-by-position basis for the purposes of determining executive compensation for 2014. This 2014 peer group differed from our 2013 peer group as follows: Cymer, Inc. and Varian Medical Systems, Inc. were removed because Cymer, Inc. was acquired by ASML Holding NV in May 2013 and Varian Medical Systems, Inc.’s revenues and market capitalization no longer fit within the desired range for our peer group. Additionally, Daktronics, Inc. was added because of its similar size in terms of revenues and market capitalization.

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Role of our Chief Executive Officer

Our Chief Executive Officer reviews with the Compensation Committee the performance of all other executive officersNamed Executive Officers and makes recommendations relating to compensation of such executive officers. Management develops proposed corporatecompany financial goals for review and approval by the Compensation Committee for the annual cash incentive plan and long-term performance-based equity incentive compensation, develops proposals relating to potential changes in compensation programs for review and approval by the Compensation Committee and provides the Compensation Committee and its advisors with information necessary to evaluate and implement compensation proposals and programs. Our Chief Executive Officer does not participate in discussions regarding his own compensation.

Governance Policies

Stock Ownership Guidelines

Our Stock Ownership Guidelines, which are applicable to members of the Board of Directors, the Chief Executive Officer and any other person who is or was a Named Executive Officer while the guidelines are effective, provide that:

These guidelines are based, in each case, on values in effect as of December 31 of the applicable year.

We adopted the Stock Ownership Guidelines in 2013 and they provide for aphase-in period over five years to achieve the respective ownership goals. We modified these guidelines to increase the threshold for directors from four times the annual retainer to five times effective for 2018.

Clawback Policy

Our Clawback Policy, which is applicable to incentive-based compensation (specifically our cash incentive plan and our performance-based RSUs) that is awarded to executive officers,Named Executive Officers, provides that in the event we are required to prepare an accounting restatement due to material noncompliance with financial reporting requirements, we will use reasonable efforts to recover any amount in excess of what would have been paid to such executive officersNamed Executive Officers (or such former executive officers)Named Executive Officers) under the accounting restatement for any such incentive-based compensation during the three-year period preceding the restatement.

Prohibition on Hedging and Pledging

Our Insider Trading Policy prohibits any of our directors or employees from engaging in transactions involving financial instruments that are designed to hedge or offset any decrease in the market value of our securities (includingpre-paid variable forward contracts, equity swaps, collars and exchange funds), and prohibits such individuals from purchasing our securities on margin or pledging such securities as collateral for a loan.

Impact of Accounting and Tax on Executive Compensation

Impact of Code Section 162(m)

Prior to the Tax Act that was signed into law in December 2017, Section 162(m) of the Internal Revenue Code of 1986, as amended, generally disallowsdisallowed a tax deduction to public companies for compensation in excess of $1 million per person paid to a company’s chief executive officer and the next three most highly-paid executive officers other than the chief financial officer. Certain compensation, including qualified performance-based compensation, willwas not be subject to the deduction limit ifso long as certain requirements arewere met. The Tax Act eliminates this performance-based compensation exception to the deduction limitation and expands the definition of employees to include the chief financial officer. Certain grandfathered performance-based compensation remains exempt from the deduction limit so long as such compensation was deductible in a company’s 2017 fiscal year or was outstanding on November 2, 2017 pursuant to a binding written agreement which has not since been modified, and certain other requirements have been met. In general, however, for fiscal years beginning after December 31, 2017, all compensation (other than grandfathered compensation) in excess of $1 million paid to the specified executives will not be deductible.

For the Company’s 2017 fiscal year, the Compensation Committee reviewsstructured awards to executive officers under the potential effect of Section 162(m)

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periodically. On May 5, 2014, we received shareholder approval for the 2014 Stock Incentive Plan which permits the grant of Section 162(m) qualifiedCompany’s annual cash and equity performance-based RSUs and restricted stock. At the 2015 Annual Meeting, we are seeking shareholder approval of our 162(m) Executive Cash Incentive Planincentive compensation programs so that cash bonuses and performance-based equity awards under such plan will qualify asqualified for the performance-based compensation exemption under Section 162(m). TheWith the elimination of this exemption with respect to future performance-based awards, the Compensation Committee will be reviewing the Tax Act, and its application and impact on our Company’s compensation programs; however, the Compensation Committee reserves the right to use its judgment to authorize compensation payments which are not qualified as performance-based compensation under Section 162(m) and which may be in excess of the Section 162(m) deduction limit when the Compensation Committee believes such payments are appropriate after taking into consideration changing business conditions or the officer’s performance, and are in the best interests of our shareholders. The Compensation Committee believes that shareholder interests are best served by not restricting the Compensation Committee’s discretion and flexibility in structuring compensation programs, even though such programs may result innon-deductible compensation expenses.

Impact of ASC 718

We account for stock-based compensation in accordance with the requirements of Financial Accounting Standards Board Accounting Standards Codification 718 (“ASC 718”).718. The Compensation Committee considers the impact of ASC 718 on our use of equity incentives as a key retention tool. The Compensation Committee regularly reviews its choice of equity instruments, taking into account both tax and accounting considerations.

COMPENSATION COMMITTEE REPORT

The Compensation Committee has reviewed and discussed the “Compensation Discussion and Analysis” required by Item 402(b) of RegulationS-K with management. Based on such review and discussions, the Committee recommended to the Board of Directors that the “Compensation Discussion and Analysis” be included in this proxy statement.

Respectfully submitted,

Robert R. Anderson,Elizabeth A. Mora, Chair

Cristina H. Amon

Peter R. Hanley

Rick D. Hess

EXECUTIVE COMPENSATION TABLES

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Summary Compensation Table for 20142017

The following table sets forth the aggregate amounts of compensation earned by our Named Executive Officers in the years ended December 31, 2014, 20132017, 2016 and 2012.2015:

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out-of-pocket healthcare costs, $1,950 for his executive physical and $7,950 for 401(k) matching contributions; with respect to 2015, this amount was comprised of $16,115 for car related expenses, $6,470 for golf membership, $25,621 for company paid health and life insurance, $1,780 for reimbursement ofout-of-pocket healthcare costs, and $7,950 for 401(k) matching contributions. For Mr. Bagshaw: with respect to 2017, this amount was comprised of $9,349 for car related expenses, $6,630 for golf membership, $30,786 for company paid health and life insurance, $4,500 for reimbursement ofout-of-pocket healthcare costs, $3,000 for his executive physical and $8,100 for 401(k) matching contributions; with respect to 2016, this amount was comprised of $10,560 for car related expenses, $6,470 for golf membership, $33,229 for company paid health and life insurance, $4,500 for reimbursement ofout-of-pocket healthcare costs, $2,850 for his executive physical, a discretionary gift card award of $1,000 plus a tax gross up of $889 and $7,950 for 401(k) matching contributions; with respect to 2015, this amount was comprised of $8,862 for car related expenses, $6,470 for golf membership, $31,200 for company paid health and life insurance $4,500 for reimbursement ofout-of-pocket healthcare costs, and $7,950 for 401(k) matching contributions. For Mr. Abrams: with respect to 2017, this amount was comprised of $14,157 for car related expenses, $6,630 for golf membership, $30,626 for company paid health and life insurance, $4,500 for reimbursement ofout-of-pocket healthcare costs, and $8,100 for 401(k) matching contributions; with respect to 2016, this amount was comprised of $11,791 for car related expenses, $31,529 for company paid health and life insurance, a discretionary gift card award of $500 plus a tax gross up of $240 and $7,950 for 401(k) matching contributions; with respect to 2015, this amount was comprised of $10,199 for car related expenses, $29,154 for company paid health and life insurance and $7,800$7,950 for 401(k) matching contributions. WithFor Dr. Lee: with respect to 2013,2017, this amount was comprised of $16,165$13,239 for car related expenses, $6,165$6,630 for golf club membership, $19,170$36,132 for company paid health and life insurance, $720$4,500 for a lengthreimbursement of service awardout-of-pocket healthcare costs, and $7,650$8,100 for 401(k) matching contributions. Withcontributions; with respect to 2012,2016, this amount was comprised of $14,260$13,634 for car related expenses, $5,870$6,470 for golf club membership, $25,250$38,446 for company paid health and life insurance, $4,500 for reimbursement ofout-of-pocket healthcare costs, and $7,500$7,950 for 401(k) matching contributions. For Mr. Bagshaw,contributions; with respect to 2014,2015, this amount was comprised of $26,027$13,516 for car related expenses, $6,165$6,470 for golf club membership, $28,457$37,672 for company paid health and life insurance, $4,500 for reimbursement ofout-of-pocket healthcare costs, and $7,800$7,950 for 401(k) matching contributions. WithFor Mr. Werth: with respect to 2013,2017, this amount was comprised of $17,180$8,400 for car related expenses, $6,165 for golf club membership, $27,306$33,696 for company paid health and life insurance, $4,500 for reimbursement ofout-of-pocket healthcare costs, $4,000 for company paid financial planning services and $7,650$8,100 for 401(k) matching contributions. Withcontributions; with respect to 2012,2016, this amount was comprised of $13,858 for$4,200 in car related expenses $5,870 for golf club membership, $28,083and $13,830 for company paid health and life insurance and $7,500that we paid since he joined our Company in April 2016. Reimbursement ofout-of-pocket health care costs is capped at $4,500 annually. Mr. Colella was reimbursed $5,784 in 2017 for 401(k) matching contributions. For Mr. Abrams, with respectsuch costs, however, $1,284 of which related to 2014, this amount was comprised of $16,589out-of-pocket healthcare costs incurred in 2016 but submitted for car related expenses, $20,354 for company paid health and life insurance and $7,800 for 401(k) matching contributions. For Dr. Lee, with respect to 2014, this amount was comprised of $23,093 for car related expenses, $6,165 for golf club membership, $29,312 for company paid health and life insurance, $850 for a patent award and $7,800 for 401(k) matching contributions. With respect to 2013, this amount was comprised of $22,880 for car related expenses, $6,150 for golf club membership, $24,758 for company paid health and life insurance, and $7,650 for 401(k) matching contributions. With respect to 2012, this amount was comprised of $19,779 for car related expenses, $3,779 for golf club membership, $28,217 for company paid health and life insurance, $850 for a patent award and $7,500 for 401(k) matching contributions. For Mr. Quirk, with respect to 2014, this amount was comprised of $30,543 for car related expenses, $6,165 for golf membership, $16,288 for company paid health and life insurance and $7,800 for 401(k) matching contributions.reimbursement in 2017.

26CEO Pay Ratio

The purpose of this new disclosure is to provide a measure of the equitability of pay within our Company. We believe our compensation philosophy and process yield an equitable result for all of our employees. During 2017, our principal executive officer was our Chief Executive Officer and President, Gerald Colella. For 2017, the combined annual total compensation for Mr. Colella was $8,442,721, and for our median employee was $64,024, resulting in a pay ratio of approximately 132:1.

In accordance with Item 402(u) of RegulationS-K, we identified the median employee as of December 18, 2017 (the median employee determination date) by (i) aggregating for each applicable employee (A) annual base salary for salaried employees (or hourly rate multiplied by expected annual work schedule for hourly employees), (B) the actual bonus, commissions and overtime or double-time received for 2017, and (C) the accounting value of any equity granted during 2017, and (ii) ranking this compensation measure for our employees from lowest to highest. This calculation was performed for all employees, excluding Mr. Colella, whether employed on a full-time, part-time, or seasonal basis. For purposes of identifying the median employee, we converted amounts paid in foreign currencies to United States Dollars based on the applicable 2017 average exchange rates as of December 18, 2017.

The pay ratio reported above is a reasonable estimate calculated in a manner consistent with SEC rules based on our internal records and the methodology described above. Because the SEC rules for identifying the median compensated employee and calculating the pay ratio based on that employee’s annual total compensation allow companies to adopt a variety of methodologies, to apply certain exclusions, and to make reasonable estimates and assumptions that reflect their employee populations and compensation practices, the pay ratio reported by other companies may not be comparable to the pay ratio reported above, as other companies have different employee populations and compensation practices and may utilize different methodologies, exclusions, estimates and assumptions in calculating their own pay ratios.

Grants of Plan-Based Awards Table in Fiscal Year 20142017