UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 14A

(Rule14A-101)

INFORMATION REQUIRED IN

PROXY STATEMENT

SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.     )

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

Check the appropriate box:

MKS INSTRUMENTS, INC.

2 Tech Drive, Suite 201

Andover, Massachusetts 01810

NOTICE OF 20192020 ANNUAL MEETING OF SHAREHOLDERS

TO BE HELD ON MAY 8, 201912, 2020

To our Shareholders:

The 20192020 Annual Meeting of Shareholders of MKS INSTRUMENTS, INC., a Massachusetts corporation, will be held on Wednesday,Tuesday, May 8, 201912, 2020 at 10:00 a.m., Eastern Time, at MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, Massachusetts 01810 for the following purposes:

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

We provide 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 mail to our shareholders a Notice of Internet Availability of Proxy Materials, which we refer to as the Notice. We are mailing the Notice on or about March 28, 2019,27, 2020, and it contains instructions on how to access the proxy statement and our Annual Report for the fiscal year ended December 31, 2018,2019, which we refer to as the 20182019 Annual Report, 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 20182019 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.

The Board of Directors has fixed the close of business on March 6, 20194, 2020 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. Your vote is important no matter how many shares you own. Whether you expect to attend the meeting or not, please vote your shares by using the Internet as described in the instructions included onin 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 returning your proxy card or voting instruction form.card. 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. CHUTEKATHLEEN F. BURKE

Secretary

Andover, Massachusetts

March 28, 201927, 2020

TABLE OF CONTENTS

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ii

MKS INSTRUMENTS, INC.

2 Tech Drive, Suite 201

Andover, 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 20192020 Annual Meeting of Shareholders to be held on May 8, 201912, 2020 at 10:00 a.m., Eastern Time, at MKS Instruments, Inc., 2 Tech Drive, Suite 201, Andover, Massachusetts 01810, and at any adjournment or postponement thereof, which we refer to as the 2020 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 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 20192020 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 2020 Annual Meeting will not in itself be deemed to revoke a proxy unless the shareholder gives affirmative notice at the 2020 Annual Meeting that the shareholder intends to revoke the proxy and vote in person.

We provide 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 mail to our shareholders a Notice of Internet Availability of Proxy Materials, which we refer to as the Notice. We are mailing the Notice on or about March 28, 2019,27, 2020, and it contains instructions on how to access the proxy statement and our Annual Report for the fiscal year ended December 31, 2018,2019, which we refer to as the 20182019 Annual Report, 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 20182019 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 8, 201912, 2020

This proxy statement and the 20182019 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, 20182019 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 6, 2019,4, 2020, the record date for the determination of shareholders entitled to notice of, and to vote at, the 2020 Annual Meeting, there were issued and outstanding and entitled to vote 54,224,96454,871,406 shares of our common stock, no par value per share, which we refer to as our Common Stock. Each outstanding share entitles the record holder to one vote on each matter submitted at the 2020 Annual Meeting.

In order to transact business at the 2020 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 2020 Annual Meeting shall constitute a quorum for the transaction of business at the 2020 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 2020 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, which we refer to as a Majority Withhold 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 IIIII 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 atinvestor.mksinst.com in the Corporate Governance tab. The advisory vote on executive compensation (Proposal Two) and the ratification of PricewaterhouseCoopers LLP (Proposal 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 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 majority of the votes cast on the matter. 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.

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 2021 Annual Meeting of Shareholders, the term of the Class II Directors expires at the 20192022 Annual Meeting of Shareholders and the term of the Class III Directors expires at the 2020 Annual Meeting. Our Board of Directors, upon the recommendation of our Nominating and Corporate Governance Committee, has nominated Jacqueline F. MoloneyJoseph B. Donahue and Michelle M. WarnerJanice K. Henry to serve as Class IIIII Directors for a term to expire at the 20222023 Annual Meeting. Ms. Moloney currently serves as a director.Meeting of Shareholders. 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 either 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.

THE BOARD OF DIRECTORS BELIEVES THAT APPROVAL OF THE ELECTION OF JACQUELINE F. MOLONEYJOSEPH B. DONAHUE AND MICHELLE M. WARNERJANICE K. HENRY TO SERVE AS CLASS IIIII DIRECTORS IS IN THE BEST INTERESTS OF MKS AND OUR SHAREHOLDERS AND THEREFORE RECOMMENDS A VOTE “FOR” BOTH NOMINEES.

DIRECTORS

Set forth below are the names and ages of each member of our Board of Directors (including those who areand our two director nominees, for election as Class II Directors)Joseph B. Donahue and Ms. Warner,Janice K. Henry, 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. We have also included information about each individual’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 individual, directly or indirectly, as of January 1, 2019,2020, appears in this proxy statement under the heading “Security Ownership of Certain Beneficial Owners and Management.” Richard S. ChuteJohn R. Bertucci, Gregory R. Beecher and Peter R. Hanley,Rick D. Hess, who currently serve as Class IIIII Directors, are not standing forre-election to the Board of Directors and, accordingly, their tenure as directors will end as of the date of our 20192020 Annual Meeting on May 8, 2019.12, 2020. For this reason, their biographical information and qualifications have been omitted below.

Agreements asDirector Skills, Experience and Background

MKS is a global provider of instruments, systems, subsystems and process control solutions that measure, monitor, deliver, analyze, power and control critical parameters of advanced manufacturing processes to Nomination

Mr. Bertucci resigned from his employment withimprove process performance and productivity for our customers. Many of the markets for our products are cyclical and highly competitive. As we discuss below under Corporate Governance – Director Candidates, the Nominating and Corporate Governance Committee is responsible for evaluating the appropriate skills, experience and background that MKS effective December 31, 2006. Mr. Bertucci’s employment agreement provided that if Mr. Bertucci resigned from his employment, then, subject to applicable law,seeks in Board members in the context of our Amended and RestatedBy-Laws, our Restated Articles of Organizationbusiness and the existing composition of the Board. This evaluation includes numerous factors, such as integrity, business acumen, knowledge of our business and industry, effectiveness, experience, diligence, conflicts of interest and the ability to act in the interests of all shareholders.

Listed below are the skills and experience that we consider important for our directors given our current business and organizational structure. The continuing directors’ fiduciary duties,and director nominees’ biographies and the matrix below note each director’s and director nominee’s relevant experience, qualifications and skills relative to this list.

Skills/Competencies

A significant portion of our sales are derived from products sold to semiconductor capital equipment manufacturers and semiconductor device manufacturers. In addition, our products are used in the industrial technologies, life and health sciences, as well as research and defense markets. Directors who have education and experience in semiconductor technology and other industrial technologies are valuable for their perspectives on our research and development efforts, competing technologies, the products and processes we develop, our manufacturing and assembly and the markets in which we compete.

Directors with a background in mergers and acquisitions, and business development provide insights into developing and implementing strategies for growing our business. Useful experience in this area includes skills in assessing and analyzing the “fit” of a proposed acquisition with our long-term strategy, valuing transactions and assessing management’s integration plans with existing operations.

Directors who have served in senior leadership positions are important to us because they have the experience and perspective to analyze, shape, and oversee the execution of important operational and policy issues.

Directors with public company board experience understand the dynamics and operation of a corporate board, the relationship of a public company board to the Chief Executive Officer and other executive officers, the legal and regulatory landscape in which public companies must operate, and how to oversee an ever-changing mix of strategic, operational, and compliance-related matters.

We are a global organization with manufacturing, research and development, and sales offices in many countries. We sell our products to thousands of customers worldwide and a significant portion of our revenues are from sales to customers in international markets. Our manufacturing facility locations include Austria, China, France, Germany, Israel, Italy, Mexico, Romania, Singapore, South Korea, the United Kingdom and the United States. Because of these factors, directors with international experience can provide valuable business, regulatory and cultural perspectives regarding many important aspects of our business.

Functional Background

Knowledge of financial markets, financing operations, and accounting and financial reporting processes is very important as it assists our directors in understanding, advising on, and overseeing our capital structure, financing and investing activities as well as our financial reporting and internal controls.

Our products incorporate sophisticated technologies to measure, monitor, deliver, analyze, power and control complex semiconductor and advanced manufacturing processes, thereby enhancing uptime, yield and throughput for our customers. We have developed, and continue to develop, new products to address industry trends. Directors with education and experience in engineering, and research and development provide valuable perspectives regarding our research and development efforts, competing technologies, the products and processes we develop, our manufacturing and assembly and the markets in which we compete.

Directors with a regulatory, legal or governance background can assist the Board in fulfilling its oversight responsibilities regarding our compliance, engagement with regulatory authorities, and governance structure.

Directors with marketing, brand management and sales experience can provide expertise and guidance as we seek to grow sales, expand the markets in which we compete, and strengthen our brands.

As we operate in many cyclical markets, with rapid demand changes, and have a broad footprint of international manufacturing operations, understanding of and experience with manufacturing and other operational processes are valuable assets to our Board.

The markets we serve increasingly rely on digitization and electronic connectivity as growth drivers, including, for example, the Internet of Things, or IoT. Further, we rely on various information technology networks and systems, some of which are managed by third parties, to process, transmit and store electronic information and to carry out and support a variety of business activities, and the safety and security of our digital information is paramount to our success. Directors shall nominate Mr. Bertucci for election aswho have a Class III Directorsophisticated understanding of global digitization, and/or cybersecurity literacy can assist with the Board’s oversight of driving future growth and consider Mr. Bertucci for appointment as Chairmansecuring our digital information in the rapidly evolving digital landscape.

Personal Demographics

Representation of a mix of ages, gender and racially diverse perspectives expand the Board’s understanding of the needs and perspectives of our customers, suppliers, employees and stockholders. In addition, we consider the tenure each director has on our Board.

Board Skills Matrix

Listed below are the skills and competencies that we consider important for our directors and director nominees to ensure effective oversight of Directors, until such time as Mr. Bertucci is no longer eligiblethe Company’s business. The continuing directors’ and director nominees’ biographies note each continuing director’s and director nominee’s relevant experience, qualifications and skills relative to this list.

Current Members

Nominees

1

2

3

4

5

6

7

8

9

1

2

SKILLS/COMPETENCIES

•  Industry Experience

✓

✓

✓

✓

✓

✓

✓

✓

✓

•  M&A Business Development Experience

✓

✓

✓

✓

✓

✓

✓

✓

✓

•  CEO/COO/CFO Experience

✓

✓

✓

✓

✓

✓

✓

✓

✓

✓

•  Experienced Director

✓

✓

✓

✓

✓

✓

✓

•  International Experience

✓

✓

✓

✓

✓

✓

✓

✓

✓

FUNCTIONAL BACKGROUND

•  Accounting/Finance

✓

✓

✓

•  Engineering/R&D

✓

✓

✓

✓

✓

•  Regulatory/Legal/Governance

✓

✓

✓

•  Marketing/Sales

✓

✓

✓

•  Operations

✓

✓

✓

✓

✓

•  Digitization/Cybersecurity/IoT

✓

✓

✓

PERSONAL DEMOGRAPHICS

•  Tenure (years)

50

2

14

6

3

4

8

1

0

0

0

•  Age

79

52

62

63

66

66

59

53

57

68

61

•  Gender (Female/Male/Nonbinary)

M

M

M

M

M

F

F

F

M

F

M

•  Racial Diversity(Caucasian/Non-Caucasian)

C

N

C

C

C

C

C

C

N

C

C

Demographic Ratio Graphs

The following demographic ratio graphs show data for nomination as a director.our continuing directors and director nominees.

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 2019 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 2019 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,executive officers, who are critical to our success. Under these programs, our Named Executive Officersexecutive 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 2019 Named Executive Officers for the 2018 fiscal year.Officers.

The Compensation Committee continually reviews the compensation programs for our Named Executive Officersexecutive 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 2019 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 2019 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 2019 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, 2019.2020. PwC was our independent registered public accounting firm for the fiscal year ended December 31, 2018.2019.

Representatives of PwC are expected to be present at the 2020 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 2020 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, 20192020 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 Dr. Lee, are independent as defined under the rules of the Nasdaq Stock Market, 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 of 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. Mr. Bertucci, who has been our Chairman of the Board of Directors since 1995, will not be standing forre-election to the Board and, accordingly, his tenure as a director and Chairman will end as of the date of our 2020 Annual Meeting on May 12, 2020. Mr. Colella, our former Chief Executive Officer and current member of our Board of Directors, will assume the role as Chairman at that time.

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 Chairman 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 currently obligated under our Corporate Governance Guidelines to have a Lead Director, as our Chairman of the Board of Directors is independent, we will be required to have currently elected to continue to do so.a Lead Director in May 2020 when Mr. Colella, our former Chief Executive Officer and anon-independent member of our Board of Directors, assumes the role of Chairman. Mr. Beecher, who has served asbeen our Lead Director since 2012.2012, will not be standing forre-election to the Board and, accordingly, his tenure as a director and Lead Director will end as of the date of our 2020 Annual Meeting on May 12, 2020. The Board will appoint a new Lead Director at that time.

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 interests of the independent directors, as appropriate. Pursuant to our Corporate Governance Guidelines, which are posted on our website atinvestor.mksinst.com in the Corporate Governance tab, the Lead Director shall, among other matters:

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.planning. 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, corporate governance and corporate governance.social responsibility. 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 chair of the relevant committee reports on the discussion to the full Board of Directors.

Board of Director Meetings and Committees of the Board of Directors

The Board of Directors held sixfour meetings in 2018.2019. During 2018,2019, 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 Meetingannual meeting of Shareholders.shareholders. All of the directors then serving on the Board of Directors, other than Messrs. Chute and Hanley, who were not standing forre-election at the 2019 Annual Meeting, attended the 20182019 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 on our website atinvestor.mksinst.com in the Corporate Governance tab.

Compensation Committee

The Compensation Committee consists of Ms. Mora (Chair), Mr. Batra Dr. Hanley and Mr. Hess. Dr. Peter R. Hanley also served on the Compensation Committee until May 2019 when his tenure as a director ended. Each member of the Compensation Committee meets the requirements for independence under applicable Nasdaq and SEC rules. The Compensation Committee’s responsibilities include:

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee consists of Ms. Moloney (Chair), Mr. Chute (Chair),Batra and Ms. Warner. Mr. Batra and Ms. Warner replaced Dr. Hanley and Ms. Moloney.Richard S. Chute, each of whom stepped down in May 2019 when his tenure as a director ended. 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:

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. The Nominating and Corporate Governance Committee also assesses the candidate’s professional background and skills against those of the existing Board members to ensure a breadth and diversity of expertise that suits the Company’s current and future business risks, industries and challenges. See “Directors — Board Skills Matrix.” 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 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 and Secretary, 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.

In October 2017,February 2020, the Board of Directors, upon the recommendation of the Compensation Committee, increased,approved several changes to ournon-employee director cash compensation program. The Compensation Committee recommended these changes after reviewing a competitive analysis of director compensation programs of our peer group prepared by the Committee’s independent compensation consultant, Pearl Meyer, and finding that certain components of board compensation fell below the median of our peer group. The table below sets forth the cash compensation payable by usto non-employee directors under the new cash compensation program effective Aprilas of January 1, 2018, the base retainer from $60,000 to $70,000 and the Chairman retainer from $45,000 to $60,000.2020:

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 2018,2019, under our director compensation program,non-employee directors received automatic grants of restricted stock units, or RSUs, on the date of the 20182019 Annual Meeting of Shareholders, with a grant date value of $170,000, which RSUs shall vest in full on the day prior to the first2020 Annual Meeting. In February 2020, the Board of Directors, upon the recommendation of the Compensation Committee, increased the value of the annual meeting of shareholders followingRSU grant to $200,000 foreach non-employee director, effective on the date of grant (or if no such meeting is held within 13 monthsthe 2020 Annual Meeting. Our Compensation Committee recommended this increase after reviewing the dateboard compensation analysis discussed above under Director Compensation — Cash Compensation and finding that the equity compensation paid tonon-employee members of grant, onour Board fell below the 13 month anniversarymedian of the date of grant).our peer group.

If a newnon-employee director joins our Board of Directors after our annual meeting of shareholders but before January 1^st1st 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 $276,201$326,082 as of December 31, 2018. The agreement requires that he make an annual contribution towards the retiree benefits of $1,500.2019. Mr. Bertucci also receives a car allowance for life, which had a net present value of $174,018$169,444 as of December 31, 2018.2019. Mr. Bertucci receives no other retirement benefits.

The following table summarizes compensation paid tonon-employee directors in 2018.2019. Mr. Colella is excluded from the table because he iswas an executive officer in 2019, and his compensation is set forth in the Executive Compensation section below, under the heading “Executive Compensation Tables — Summary Compensation Table for 2018.2019.”

Director Compensation Table for 20182019

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 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, 2018.2019.

Respectfully submitted,

Gregory R. Beecher, Chair

Jacqueline F. Moloney

Elizabeth A. Mora

Principal Accountant Fees and Services

For the years ended December 31, 20182019 and 2017,2018, aggregate fees for professional services rendered by 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 (v) the audit of our internal controls over financial reporting as required by the rules and regulations promulgated under Section 404 of the Sarbanes-Oxley Act of 2002.

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 foregoing, 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 independent registered public accounting firm during the next 12 months. Any suchpre-approval of types of services is detailed as to the particular service or type of service to be provided and is also generally subject to a maximum dollar amount.

The Audit Committee has also delegated to the Chair of the Audit Committee the authority to approve any audit ornon-audit services to be provided to us by our independent registered public accounting firm. Any approval of services by the Chair of the Audit Committee pursuant to this 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 the beneficial ownership of our Common Stock by (i) each shareholder known to us to be the beneficial owner of more than 5% 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 director nominee;nominees; and (iv) all of our directors, director nominees 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, 2019;2020; 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.

EXECUTIVE OFFICERS

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

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.

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.

In May 2019, we announced our Chief Executive Officer succession plan. Pursuant to that plan, on January 1, 2020, our then Chief Executive Officer, Gerald G. Colella, retired and our then President, John T.C. Lee, succeeded Mr. Colella as Chief Executive Officer and continued to serve as President. Mr. Colella continues to serve on our Board of Directors and, as previously announced, will assume the role of Chairman of our Board in May 2020.

Throughout this proxy statement, we refer to the following “Named“2019 Named Executive Officers:”Officers” listed below.

Following this Compensation Discussion and Analysis, you will find a series of tables containing specific information about the compensation earned or paid in 20182019 to our 2019 Named Executive Officers. When we announced Mr. Abrams’ retirement in May of 2018, we entered into a Transition and Retirement Agreement with Mr. Abrams, which set forth, among other things, Mr. Abrams’ compensation upon his retirement. As a result, we did not make any compensation decisions with respect to Mr. Abrams during 2019 and he was not eligible for a salary adjustment or a 2019 cash bonus, and he did not receive any equity awards. For this reason, Mr. Abrams is not included in the discussion that follows. We refer to our 2019 Named Executive Officers who did serve through December 31, 2019 as the “Named Executive Officers” throughout the discussion below. References to “2019 Named Executive Officers” include Mr. Abrams. For a detailed discussion of the material terms of Mr. Abrams’ Transition and Retirement Agreement, see “Executive Compensation Tables — Potential Payments Upon Termination orChange-in-Control.”

Executive Summary

Our Business

We are a global provider of instruments, systems, subsystems and process control solutions that measure, monitor, deliver, analyze, power and control critical parameters of advanced manufacturing processes to improve process performance and productivity for our customers. Our products are derived from our core competencies in pressure measurement and control, flow measurement and control, gas and vapor delivery, gas composition analysis, residual gas analysis, leak detection,electronic control technology, ozonereactive gas generation and delivery, power reactive gas generation and delivery, vacuum technology, lasers, photonics,sub-micron positioning, optics, precision motion control, vibration control optics and laser-based manufacturing systems solutions. We also provide services relating to the maintenance and repair of our products, installation services and training. Our primary served markets include semiconductor, industrial technologies, life and health sciences, research and defense.

Company Performance in 2018 and Financial Highlights2019

2018The first half of 2019 was another outstanding yearchallenging for MKS as revenuedue to the continued downturn in our Semiconductor Market, where our customers continued to experience excess production capacity, which drove lower capital expenditures negatively impacting our business. In our Advanced Markets, heightened geopolitical and earnings per share both set new Company records. Five years ago, we settrade headwinds led to more cautious spending. In addition, the consumer electronics market also underwent a strategyprolonged period of delivering sustainable and profitable growth. Onedigestion of excess capacity. However, in the second half of the focus areas has beenyear, we saw improved fundamentals within the Semiconductor Market and stabilization in our Advanced Markets, as trade tensions started to enhance our strong semiconductor market portfolio while broadening our reach into advanced markets, which include industrial technologies, life and health sciences, research and defense. We have executed on this strategy with a combinationease. In the fourth quarter of successfully integrating key acquisitions, strengthening our product portfolio and enhancing ourgo-to-market strategies for these new markets.

On February 1, 2019, we delivered strong net revenues of $500 million and experienced strong sequential growth in our Semiconductor Market net revenues, which increased 22% in the quarter. This growth was driven by strong foundry and logic spending, as well as early signs of recovery in memory.

In February 2019, MKS completed ourthe acquisition of Electro Scientific Industries, Inc., or ESI, an innovatora worldwide leader in laser-basedadvanced manufacturing solutions forprocesses within the micro-machining industry.printed circuit board, electronic thin film and electronic component markets. Our acquisition of ESI is anotherrepresents a significant step in executing our “broadeningbroadening our market reach” strategy,reach and expanding our addressable market by approximately $2.2 billion. The acquisition also provides MKS with a verymore balanced portfolio, with approximately 51% of our combined revenue in 20182019 coming from advanced markets,Advanced Markets, and 49% from the semiconductor market, on a pro forma basis, reflecting the full year results of ESI.Semiconductor Market. We expect the addition of ESI to further strengthen our expertise in the lasers, photonics and optics markets, enabling us to develop systems that provide unique and cost-effective solutions to meet the challenges of our customers’ evolving technology needs.

below target. In 2018,2019, the variable cash compensation for all of our executive officers other than Mr. Werth, was tied to the financial performance of our Company, as a whole. The variable cash compensation for Mr. Werth, who headed up our Light and Motion Division, was tied toexcluding the financial performance of our Lightthe Company’s Equipment and Motion Division.Solutions Division, which division was formed as a result of the Company’s acquisition of Electro Scientific Industries, Inc., or ESI, in 2019.

When our Compensation Committee set 20182019 executive compensation in early 2018,2019, long-term equity incentive compensation comprised 64.5%65% of total target compensation for our Chief Executive Officer and 53.8%59.2% 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. Also, at least 50% of each Named Executive Officer’s target long-term equity incentive compensation is based on a measure of Company 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 bynon-GAAP operating income. In 2018,2019, our target annual cash incentive compensation comprised 19.4%19.1% of total target compensation for our Chief Executive Officer and 20.7%17.7% of total target compensation, on average, for our other Named Executive Officers.

In 2018,2019, base salary accounted for 16.1%15.9% of total target compensation for our Chief Executive Officer and 25.5%23.1% of total target compensation, on average, for our other Named Executive Officers. In 2018,2019, our Chief Executive Officer had 83.9%84.1% of his total target compensation opportunity tied to annual and long-term incentive compensation and our other Named Executive Officers, on average, had 74.5%76.9% of their total target compensation opportunity tied to annual and long-term incentive compensation.

Consideration of 20182019 Advisory Vote on Executive Compensation

At our 20182019 Annual Meeting of Shareholders, held on May 9, 2018,8, 2019, 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 outcome of this vote each year when

Officers relative to the market, we also look qualitatively at the individual’s overall performance, tenure and potential with MKS.contributions to MKS’ ongoing growth. Currently, all of our Named Executive Officers are paid within the competitive range of our peer group.

Base salaries are designed to provide executives with a level of predictability and stability with respect to a portion of their total compensation package. Base salaries are a relatively small component in the overall pay packages of our Named Executive Officers because we believe the significant majority of executive compensation should be variable and based on performance.

Our annual cash incentive compensation program provides a short-term incentiveis designed to reward management for reaching our annualthe attainment of short-term earnings goals and to reinforce ourpay-for-performance philosophy.that drive the long-term growth of MKS. We believe that our program providesgoals are aligned with significant value creation, and that our plan creates a strong link between pay and performance while providing meaningful incentive for our Named Executive Officers to exceed our financial goals.

We provide our Named 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:

In order to further underscore our compensation values, and enhance the efficacy of our pay programs, we have also implemented the following practices:

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 2018.2019.

When the Compensation Committee met in July 20172018 to review peer companies to be used to determine 20182019 executive compensation, the Committee elected to increase the size ofmake no changes to the peer group from 14 peer companies to 19 peer companies. Since threewith the exception of the 14 original peer companies had been acquired in the prior year (FEI Company, Linear Technology Corp. and Mentor Graphics Corporation), the following eight peer companies were added to the peer group: Advanced Energy Industries, Inc., AMETEK, Inc., Keysight Technologies, Inc.,KLA-Tencor Corporation, Kulicke and Soffa Industries, Inc., Lumentum Holdings Inc., Microsemi Corporation, and Sensata Technologies Holding.which was removed because it was acquired by Microchip Technology, Inc. in 2018. The 1918 peer companies were selected based on similar industry, market capitalization and revenue, with a revenue and market capitalization range relative to our trailing 12 month12-month revenue as of June 30, 20172018 of between .3 to 2.53 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 revenue and market capitalization of the company as of June 30, 2017 of $1.5 billion and $3.6 billion, respectively. Publicly available compensation data from the following comparable peer companies was used in determining executive compensation for 2018:2019:

Our Compensation Committee also considered size and industry-appropriate broad survey data from the 20182019 Radford Global Technology Survey.

Our executive compensation program is guided by the following principles:

earnings received during the 20182019 calendar year (i.e., base salary, including regular, holiday, vacation and sick pay, but excluding bonus payments). Bonus payouts in 2018, except for Mr. Werth,2019 were based entirely onnon-GAAP operating income after bonus and excluding any charges or income not related to the operating performance of the Company. Mr. Werth’s bonus payout in 2018 was based entirely onnon-GAAP operating income after bonus and excluding any charges or income not related to the operating performance of the Company’s Light and Motion Division.

In 2018,2019, payouts under the annual cash incentive plan were determined by multiplying a Named Executive Officer’s “Target Bonus Amount” by the Company’s percentage achievement of the financial performance objective, each as discussed below. Target Bonus Amount is the amount determined by multiplying each Named Executive Officer’s eligible earnings in 20182019 by the Target Bonus percentagesPercentages determined by our Compensation Committee each year. When our Compensation Committee set 20182019 annual executive compensation in early 2018,2019, it did not approve any increaseschanges to Target Bonus percentagesPercentages for our Named Executive Officers except for Mr. Colella. The Compensation Committee increased Mr. Colella’s Target Bonus percentage by 15 percentage points after reviewing the compensation data collected from our peer group and considering the strong financial performance of the Company under Mr. Colella’s leadership, including the integration of the Newport acquisition as well as the Company’s achievement of other strategic initiatives.

Dr. Lee received a Target Bonus percentage increase of five percentage points in May 2018 when he was promoted from Senior Vice President and Chief Operating Officercompared to President and Chief Operating Officer of the Company. This increase took effect on May 9, 2018 resulting in the blended rate listed below for 2018.

Listed below is the 20182019 Target Bonus Percentage for each Named Executive Officer.

In 2018,2019, our Compensation Committee approved goals and associated incentive payout opportunities related to our 2019non-GAAP operating income performance. As we operate in the highly cyclical semiconductor market, our Compensation Committee views it of paramount importance to set performance goals that are rigorous but attainable given the outlook for the semiconductor market and the other markets in which we serve for the coming year. The rigor of our performance goals for 2019 is evidenced by the fact that our funding for the 2019 annual incentive plan was below target despite the fact we had a strong performance year.

In 2019, participants other than Mr. Werth,in the annual cash compensation plan would not receive any portion of their Target Bonus Amount ifnon-GAAP operating income (before the calculation of bonus) was less than $272.3$195.9 million. Participants would receive 50% of their Target Bonus Amount if suchnon-GAAP operating income was $272.3$195.9 million, would

OurExcept as noted below, our Compensation Committee did not make any design changes to our 20192020 annual cash incentive program. For all Named Executive Officerseligible participants, Company performance will be measured using the same financial metric as in previous years –non-GAAP operating income after bonus and excluding any charges or income not related to the operating performance of the Company.

In 2018,2019, our Named Executive Officers would have forfeited all of their performance-based RSUs if our adjustednon-GAAP cash flow from operations was less than $334.1$264.9 million at a revenue level of $1.85$1.5 billion, or if such cash flow was less than $482.5$448.8 million at a revenue level of $2.3 billion (with intermediate adjustednon-GAAP cash flow minimum thresholds at different revenue levels in between). However, if we did achieve these adjustednon-GAAP 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 adjustednon-GAAP cash flow from operations was at or above $451.0$357.5 million at a revenue level of $1.85$1.5 billion, or was at or above $651.5$605.7 million at a revenue level of $2.3 billion (with proportional thresholds in between), then our Named Executive Officers would receive the maximum of 150% of their target performance-based RSUs. Proportional paymentsachievement levels would be made for adjustednon-GAAP cash flow achievements between the minimum and maximum levels. In 2018,2019, because our revenue was $2.1$1.73 billion, after excluding revenue from our Equipment and Solutions Division, which was formed as a result of our acquisition of ESI in 2019, and including revenue amounts unrecorded due to trade restrictions, and our adjustednon-GAAP cash flow was $509.1$343.4 million, after excluding restructuring charges, executive retirement costs, costs related to tariff and trade restrictions, a legal settlement, acquisition-relatedacquisition costs and related term loan fees and costs, integration costs, impairment of investment charges, a gain on the sale of property, and the tax effect of each of these excluded costs, in addition to amortization of intangible assets, depreciation of fixed assets, and stock-based compensation expense and tax adjustments resulting from additional guidance from the IRS regarding 2017 tax reform, our Named Executive Officers received 102%82% 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.

Dr. Lee received an additional award of 771 time-based RSUs and 771 performance-based RSUs (at target achievement and capped at 1,157 RSUs at maximum achievement of 150% of target) in May 2018 when he was promoted from Senior Vice President and Chief Operating Officer to President and Chief Operating Officer of

Compensation Tables — Retirement and Post-Employment Tables — Pension Benefits” below for a description of the supplemental retirement benefits we provide to Mr. Colella. Since 2011, it has been our policy not to offer these types of retirement benefits to other Named Executive Officers.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.

Perquisites

We offer certain perquisites to our executive officers, including our 2019 Named Executive Officers, to allow executives to focus on corporate strategy and enhancing shareholder value and to provide competitive pay packages. These perquisites include car payments, company paid health and life insurance, reimbursement of certainout-of-pocket healthcare costs, golf club 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 other than Mr. Abrams who entered into a Transition and Retirement Agreement with the Company on May 9, 2018 as described below, is entitled to certain payments and benefits in the event his or her employment terminates under specified 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 his or her termination of employment for a 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 or her 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 orChange-in-Control” for more information about these agreements.

Compensation Consultant

We 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:

SinceFrom October 2014 through May 2019, the Compensation Committee has engaged Meridian as its compensation consultant. The Compensation Committee determined that the engagement of Meridian as a compensation consultant did not raise any conflicts of interest with MKS. In May 2019, the Compensation Committee elected to engage a new compensation consultant, Pearl Meyer. The Compensation Committee has determined that the engagement of Pearl Meyer as a compensation consultant does not raise any conflicts of interest with MKS.

Role of our Chief Executive Officer

Our Chief Executive Officer reviews with the Compensation Committee the performance of all other Named Executive Officers and makes recommendations relating to compensation of such executive officers. Management develops proposed company 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.

In October 2019, our Board of Directors, upon the recommendation of our Compensation Committee, made the following changes to increaseour Stock Ownership Guidelines, which changes are effective as of January 1, 2020:

The purpose of these changes was to: (i) facilitate self-monitoring by adding a fixed goal to the holding requirements that was not dependent on variable stock price calculations and (ii) increase our Chief Executive Officer’s ownership goal from three times his annual base salary to five times his annual base salary to align with shareholder interests. All Named Executive Officers and directors were in 2018.compliance with the Stock Ownership Guidelines as of the end of December 2019.

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 Named Executive Officers,our current and former 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 Named Executive Officersexecutive officers (or such former Named Executive Officers)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)

Section 162(m) of the Internal Revenue Code of 1986, as amended, or the Code, generally disallows a tax deduction to public companies for compensation in excess of $1 million paid in any one year to each of the company’s chief executive officercertain current and the next three most highly compensatedformer executive officers (other thanof the chief financial officer). Pursuant to tax legislation signed into law on December 22, 2017, or the Tax Act, for taxable years beginning after December 31, 2017, the Section 162(m) deduction limitation is expanded so that it also applies to compensation in excess of $1 million paid to a public company’s chief financial officer.company. Historically, compensation that qualified under Section 162(m) as performance-based compensation was exempt from the deduction limitation. However, subject to certain transition rules, the Tax Acttax legislation signed into law on December 31, 2017 eliminated the qualified performance-based compensation exception.exemption. As a result, for taxable years beginning after December 31, 2017, all compensation in excess of $1 million paid in any one year to each of the Named Executive Officers described abovespecified officers that is not covered by the transition rules will not be deductible by us. The Compensation Committee reviews the potential effect of Section 162(m) periodically and uses its judgment to authorize compensation payments that may be subject to the limit when the Compensation Committee believes such payments are appropriate and in the best interests of the Company and its stockholders.

Impact of ASC 718

We account for stock-based compensation in accordance with the requirements of ASC 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,incentives, 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,

Elizabeth A. Mora, Chair

Rajeev Batra

Peter R. Hanley

Rick D. Hess

EXECUTIVE COMPENSATION TABLES

Summary Compensation Table for 20182019

The following table sets forth the aggregate amounts of compensation earned by our Named Executive Officers in the years ended December 31, 2019, 2018 2017 and 2016:2017. The titles for Mr. Colella and Dr. Lee in the table below are as of December 31, 2019. Pursuant to our previously announced Chief Executive Officer succession plan, on January 1, 2020, Mr. Colella retired as our Chief Executive Officer, and Dr. Lee succeeded him as Chief Executive Officer while continuing to serve as our President.