NOTICE OF 20232024 ANNUAL MEETING

AND

PROXY STATEMENT

		Corporate Office		U.S. Mail		Toll-Free: 1 800 9Adtran
		901 Explorer Blvd.		P.O. Box 140000		Telephone: 256 963 8000
		Huntsville, AL 35806		Huntsville, AL 35814-4000		http://www.adtran.com

March 28, 202327, 2024

Dear Stockholder:

You are cordially invited to attend the 20232024 Annual Meeting of Stockholders of ADTRAN Holdings, Inc. to be held on Wednesday, May 10, 2023,8, 2024, at 10:30 a.m., Central Time. We are pleased to announce that this year’s Annual Meeting will be a virtual meeting conducted by live webcast on the Internet. You will be able to attend and participate in the meeting by visiting www.virtualshareholdermeeting.com/ADTN2023ADTN2024 and entering the 16-digit control number included on your Notice of Internet Availability of Proxy Materials (the “Notice”) or on your proxy card if you receive the proxy materials by mail. You will not be able to attend the Annual Meeting in person.

The attached Notice of Annual Meeting of Stockholders and Proxy Statement describe the formal business to be transacted at the meeting. During the meeting, we also will report on Adtran’s operations during the past year and our plans for the future.

We have elected to take advantage of Securities and Exchange Commission rules that allow issuers to furnish proxy materials to their stockholders on the Internet. We believe that the rules will allow us to provide our stockholders with the information they need, while lowering the costs of delivery and reducing the environmental impact of the annual meeting.

Your vote, whether during the virtual meeting on May 10, 20238, 2024 or by proxy, is important. Please review the instructions on each of your voting options described in the accompanying proxy materials and the Notice you received in the mail. If you are unable to participate in the virtual meeting, I urge you to vote as soon as possible.

Sincerely,

THOMAS R. STANTON

Chairman of the Board

ADTRAN HOLDINGS, INC.

901 EXPLORER BOULEVARD

HUNTSVILLE, ALABAMA 35806

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD WEDNESDAY, MAY 10, 20238, 2024

NOTICE HEREBY IS GIVEN that the 20232024 Annual Meeting of Stockholders (the “Annual Meeting”) of ADTRAN Holdings, Inc. (the “Company”) will be held on Wednesday, May 10, 2023,8, 2024, at 10:30 a.m., Central Time, via live webcast. You can participate in the meeting by visiting www.virtualshareholdermeeting.com/ADTN2023ADTN2024 and entering the 16-digit control number included on your Notice or proxy card. If you hold your shares through an intermediary, such as a bank or broker, and do not have a control number, please contact the bank or broker. Please log in to the website by 10:15 a.m., Central Time, on the day of the meeting. There is no physical location for the Annual Meeting.

The Annual Meeting is being held for the purposes of considering and voting upon:

The Board of Directors recommends that you vote FOR each of the nineeight director nominees; FOR the adoption of the ADTRAN Holdings, Inc. 2024 Employee Stock Incentive Plan; FOR the adoption of the ADTRAN Holdings, Inc. 2024 Directors Stock Plan; FOR the approval on an advisory basis of the compensation of the Company’s NEOs; FOR the option of “EVERY YEAR” as the preferred frequency for future advisory votes on the compensation of the Company’s NEOs; and FOR the ratification of the appointment of PricewaterhouseCoopers LLP as the Company’s independent registered public accounting firm for the fiscal year ending December 31, 2023.2024. The Annual Meeting may be adjourned from time to time without notice other than announcement at the meeting or at adjournments thereof, and any business for which notice is hereby given may be transacted at any such adjournment.

Information relating to the above matters is set forth in the attached Proxy Statement. Stockholders of record at the close of business on March 13, 2023,11, 2024, are entitled to receive notice of and to vote during the Annual Meeting and any adjournments thereof.

Whether or not you plan to participate in the Annual Meeting, we urge you to review these materials carefully, which are available at https://materials.proxyvote.com/00738A.00486H. We also encourage you to vote by (i) following the instructions on the notice that you received from your broker, bank or other nominee if your shares are held beneficially in “street name” or (ii) one of the following means if your shares are registered directly in your name with the Company’s transfer agent:

You can submit questions in advance of the Annual Meeting by visiting www.proxyvote.com, entering your 16-digit control number, and using the “Questions for Management” feature. You can submit questions during the Annual Meeting by following the instructions on the meeting website. Management will answer pertinent questions in the “Investor Resources” section of our website at https://investors.adtran.com. The questions and answers will be available as soon as practicable after the Annual Meeting and will remain available for thirty (30) days after posting.

By order of the Board of Directors,

ULRICH DOPFER

MICHAEL K. FOLIANO

Senior Vice President of Finance, Chief Financial Officer, and Corporate Secretary and Treasurer

Huntsville, Alabama

March 28, 2023

27, 2024

TABLE OF CONTENTS

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PROXY STATEMENT FOR THE ANNUAL MEETING OF STOCKHOLDERS

TO BE HELD WEDNESDAY, MAY 10, 20238, 2024

This Proxy Statement, along with the accompanying Notice of Annual Meeting of Stockholders, contains information about the 20232024 Annual Meeting of Stockholders (the “Annual Meeting”) of ADTRAN Holdings, Inc. (the “Company”), including any adjournments or postponements of the Annual Meeting. The Annual Meeting will be held on Wednesday, May 10, 20238, 2024 at 10:30 a.m., Central Time. We are pleased to announce that this year’s Annual Meeting will be a virtual meeting conducted by live webcast on the Internet. You will be able to attend and participate in the meeting by visiting www.virtualshareholdermeeting.com/ADTN2023ADTN2024 and entering the 16-digit control number included on your Notice of Internet Availability of Proxy Materials (the “Notice”) or on your proxy card if you receive the proxy materials by mail. If you hold your shares through an intermediary, such as a bank or broker, and do not have a control number, please contact the bank or broker. Please log in to the website by 10:15 a.m., Central Time, on the day of the meeting. You may vote during the Annual Meeting by following the instructions available on the meeting website. There is no physical location for the Annual Meeting.

You can submit questions in advance of the Annual Meeting by visiting www.proxyvote.com, entering your 16-digit control number, and using the “Questions for Management” feature. You can submit questions during the Annual Meeting by following the instructions on the meeting website. Management will answer pertinent questions in the “Investor Resources” section of our website at https://investors.adtran.com. The questions and answers will be available as soon as practicable after the Annual Meeting and will remain available for thirty (30) days after posting.

We are providing this Proxy Statement to the stockholders of the Company in connection with the solicitation of proxies by our Board of Directors to be voted during the Annual Meeting and at any adjournments of that meeting.

On or about March 28, 2023,27, 2024, we began sending the Notice to all stockholders entitled to vote in advance of or during the virtual Annual Meeting. We encourage all of our stockholders to vote on the proposals presented, and we hope the information contained in this document will help you decide how you wish to vote.

Important Notice Regarding the Availability of Proxy Materials for the

Annual Meeting of Stockholders to be held on May 10, 2023:8, 2024:

This Notice, the Proxy Statement and the 20222023 Annual Report to Stockholders of ADTRAN Holdings, Inc. are available free of charge to view, print and download at https://materials.proxyvote.com/00738A.00486H.

Additionally, you can find a copy of our Annual Report on Form 10-K for the fiscal year ended December 31, 2022,2023, including financial statements and schedules thereto, on the website of the Securities and Exchange Commission (the “SEC”) at www.sec.gov, or in the “SEC Filings” section of our website at

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GENERAL INFORMATION ABOUT THE ANNUAL MEETING

Why is the Company soliciting my proxy?

The Board of Directors of the Company (the “Board”) is soliciting your proxy to vote at the 20232024 Annual Meeting of Stockholders to be held on Wednesday, May 10, 20238, 2024 at 10:30 a.m., Central Time, via live webcast and any adjournments of the meeting, which we refer to as the “virtual Annual Meeting” or the “Annual Meeting.” This Proxy Statement along with the accompanying Notice of Annual Meeting of Stockholders summarizes the purposes of the meeting and the information you need to know to vote during the Annual Meeting.

How can I participate in the virtual Annual Meeting?

You will be able to attend and participate in the Annual Meeting by visiting www.virtualshareholdermeeting.com/ADTN2023ADTN2024 and entering the 16-digit control number included on your Notice or proxy card. If you hold your shares through an intermediary, such as a bank or broker, and do not have a control number, please contact the bank or broker. Please log in to the website by 10:15 a.m., Central Time, on the day of the meeting. You may vote during the Annual Meeting by following the instructions available on the meeting website.

You can submit questions in advance of the Annual Meeting by visiting www.proxyvote.com, entering your 16-digit control number, and using the “Questions for Management” feature. You can submit questions during the Annual Meeting by following the instructions on the meeting website. Management will answer pertinent questions in the “Investor Resources” section of our website at https://investors.adtran.com. The questions and answers will be available as soon as practicable after the Annual Meeting and will remain available for thirty (30) days after posting.

Why did I receive a one-page notice in the mail regarding the Internet availability of proxy materials instead of a full set of proxy materials?

In accordance with rules and regulations adopted by the SEC, instead of mailing a printed copy of our proxy materials to each stockholder of record, we are furnishing proxy materials, including this Proxy Statement and our 20222023 Annual Report to Stockholders, by providing access to such documents on the Internet. Stockholders will not receive printed copies of the proxy materials unless they request them. Instead, commencing on or about March 28, 2023,27, 2024, a Notice was sent to our stockholders which instructs you on how to access and review the proxy materials on the Internet. The Notice also instructs you on how to submit your proxy via the Internet or by telephone. If you would like to receive a paper or email copy of our proxy materials, please follow the instructions for requesting such materials in the Notice.

Why am I receiving these materials?

Our Board is providing these proxy materials to you on the Internet or, upon your request, will deliver printed versions of these materials to you by mail, in connection with the Annual Meeting, which will take place on May 10, 2023.8, 2024. Stockholders are invited to participate in the virtual Annual Meeting and are requested to vote on the proposals described in this Proxy Statement.

What is included in these materials?

These proxy materials include:

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What proposals will be voted on during the Annual Meeting?

You will be voting on the matters listed below (with the Board’s recommendation on each matter):

What shares owned by me can be voted?

All shares owned by you as of the close of business on March 13, 202311, 2024 (the “Record Date”) may be voted. You may cast one vote per share of common stock that you held on the Record Date. These include shares that are: (1) held directly in your name as the stockholder of record, and (2) held for you as the beneficial owner through a stock broker, bank or other nominee. At the close of business on the Record Date, there were 78,634,18679,115,792 shares of our common stock outstanding. Each stockholder is entitled to one vote in person or by proxy for each share of common stock held on all matters properly to come before the Annual Meeting.

What is the difference between holding shares as a stockholder of record and as a beneficial owner?

Most of the Company’s stockholders hold their shares through a stock broker, bank or other nominee rather than directly in their own name. As summarized below, there are some differences between shares held of record and those owned beneficially through a nominee.

Stockholder of Record

If your shares are registered directly in your name with the Company’s transfer agent, American Stock Transfer & Trust Company, LLC, you are considered the stockholder of record with respect to those shares, and the Notice is being sent directly to you. As the stockholder of record, you have the right to grant your voting proxy directly to the persons named as proxy holders, Thomas R. Stanton, the Company’s Chief Executive Officer and Chairman of the Board, and Michael K. Foliano,Ulrich Dopfer, the Company’s Senior Vice President of Finance, Chief Financial Officer, and Corporate Secretary and Treasurer, or to vote prior to or during the virtual Annual Meeting. If you request printed copies of the proxy materials, the Company will provide a proxy card for you to use. You may also vote by Internet or by telephone, as described below under the heading “How can I vote my shares without participating in the Annual Meeting in real time?”

Beneficial Owner

If your shares are held in a stock brokerage account or by a bank or other nominee, you are considered the beneficial owner of shares held in “street name,” and a notice is being sent to you by your broker or nominee who is considered the stockholder of record with respect to those shares. As the beneficial owner, you are invited to participate in the virtual Annual Meeting. You also have the right to direct your broker on how to vote these shares. The notice that you receive from your broker or nominee should include instructions for you to direct your broker or nominee how to vote your shares. You may also vote prior to the Annual Meeting by Internet or by telephone, as described below under “How can I vote my shares without participating in the Annual Meeting in real time?” However, shares held in “street name” may be voted during the Annual Meeting by you only if you obtain a signed proxy from the record holder (broker, bank or other nominee) giving you the right to vote the shares.

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How can I vote my shares during the virtual Annual Meeting?

Shares held directly in your name as the stockholder of record or shares held beneficially in “street name” may be voted during the virtual Annual Meeting. If you choose to vote your shares during the virtual Annual Meeting and you are the stockholder of record, you will need the control number included on your Notice or proxy card. If you hold your shares in “street name” and do not have a control number, please contact the bank or broker.

How can I vote my shares without participating in the Annual Meeting in real time?

Whether you hold your shares directly as the stockholder of record or beneficially in “street name,” you may direct your vote by proxy without participating in the virtual Annual Meeting in real time. If you are the stockholder of record, you can vote by proxy by one of the following means:

If you hold your shares beneficially in “street name,” please follow the instructions provided in the notice from your broker, or, if you request printed copies of proxy materials, on the proxy card or voting instruction form. We urge you to review the proxy materials carefully before you vote. These materials are available at https://materials.proxyvote.com/00738A.00486H.

Can I revoke my proxy or change my vote?

You may revoke your proxy or change your voting instructions prior to the vote during the virtual Annual Meeting. You may enter a new vote by using the Internet or the telephone or by mailing a new proxy card or new voting instruction form bearing a later date (which will automatically revoke your earlier voting instructions), which new vote must be received by 11:59 p.m., Central Time, on May 9, 2023.7, 2024. You may also enter a new vote by participating in and voting during the virtual Annual Meeting. Your participation in the Annual Meeting will not cause your previously granted proxy to be revoked unless you specifically so request.

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What is the voting requirement to approve each of the proposals?

What does it mean if I receive more than one Notice, proxy card or voting instruction form?

It means your shares are registered differently or are held in more than one account. For each Notice you receive, please submit your vote for each control number you have been assigned. If you request and receive paper copies of proxy materials, please provide voting instructions for all proxy cards and voting instruction forms you receive.

Where can I find the voting results of the Annual Meeting?

We will announce preliminary voting results during the Annual Meeting and publish preliminary results, or final results if available, in a Current Report on Form 8-K within four business days of the Annual Meeting. If final results are unavailable at the time we file the Form 8-K, then we will file an amended report on Form 8-K to disclose the final voting results within four business days after the final voting results are known.

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What happens if additional proposals are presented during the Annual Meeting?

Other than the fourfive proposals described in this Proxy Statement, we do not expect any matters to be presented for a vote during the Annual Meeting. If you grant a proxy, the persons named as proxy holders, Thomas R. Stanton, the Company’s Chief Executive Officer and Chairman of the Board, and Michael K. Foliano,Ulrich Dopfer, the Company’s Senior Vice President of Finance, Chief Financial Officer, and Corporate Secretary and Treasurer, will have the discretion to vote your shares on any additional matters properly presented for a vote during the Annual Meeting. If for any unforeseen reason, any one or more of the Company’s nominees for director is not available as a candidate for director, the persons named as proxy holders will vote your proxy for such other candidate or candidates as may be nominated by the Board of Directors.

What is the quorum requirement for the Annual Meeting?

The quorum requirement for holding the Annual Meeting and transacting business is a majority of the outstanding shares entitled to vote or act at the meeting. The shares may be present by participating in the Annual Meeting or represented by proxy at the Annual Meeting. Both abstentions and broker non-votes are counted as present for the purpose of determining the presence of a quorum. If a quorum is not present or if we decide that more time is necessary for the solicitation of proxies, we may adjourn the Annual Meeting. We may do this with or without a stockholder vote. Alternatively, if the stockholders vote to adjourn the Annual Meeting in accordance with the Company’s Bylaws, the named proxies will vote all shares of common stock for which they have voting authority in favor of adjournment.

Who will bear the cost of soliciting proxies for the Annual Meeting?

The Company will pay the entire cost of soliciting proxies for the Annual Meeting, including the distribution of proxy materials. We have hired Georgeson Inc. to assist in the solicitation of proxies from stockholders at a fee of approximately $8,000$9,000 plus reasonable out-of-pocket expenses. We will request brokers or nominees to forward this Proxy Statement to their customers and principals and will reimburse them for expenses so incurred. If deemed necessary, we may also use our officers and regular employees, without additional compensation, to solicit proxies personally or by telephone.

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SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth information regarding the beneficial ownership of our common stock as of March 13, 2023,11, 2024, by (1) each of our directors, (2) each of our executive officers named in the Summary Compensation Table in this Proxy Statement and (3) all of our current directors and executive officers as a group, based in each case on information furnished to us by these persons. We believe that each of the named individuals and each director and executive officer included in the group has sole voting and investment power with regard to the shares shown except as otherwise noted.

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The following table sets forth information regarding the beneficial ownership of our common stock as of the date indicated for each person, other than the officers or directors of Adtran, known to us to be the beneficial owner of more than 5% of our outstanding common stock.

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PROPOSAL 1

ELECTION OF DIRECTORS

Our Board of Directors

Our Board of Directors currently consists of nineeight members. The Board has nominated Thomas R. Stanton, Johanna Hey, H. Fenwick Huss, Gregory J. McCray, Balan Nair, Brian Protiva, Jacqueline H. Rice, Nikos Theodosopoulos and Kathryn A. Walker for election as directors at the 20232024 Annual Meeting. Each of these individuals currently serves as a director.

In July 2022, the Company completed a business combination pursuant to which ADTRAN, Inc., through a merger that closed on July 8, 2022 (the “Merger”), became a wholly-owned subsidiary of the Company, and through an exchange offer that settled on July 15, 2022 (the “Exchange Offer”), the Company acquired approximately 65% of the outstanding shares of ADVA Optical NetworkingAdtran Networks SE, a company organized and existing under the laws of Germany (“ADVA”Adtran Networks,” formerly ADVA Optical Networking SE), became subsidiaries of the Company (the “Business Combination”). Each of Messrs. Stanton, Huss, McCray and Nair and Mses. Rice and Walker, the directors of ADTRAN, Inc., was elected to the Board of the Company, as the successor issuer to ADTRAN, Inc., upon In connection with the closing of the Merger. Upon consummation of the Exchange Offer,Business Combination, each of Johanna Hey, Brian Protiva and Nikos Theodosopoulos was elected to the Company’s Board, and Mr. Protiva was named Vice Chairman of the Board. The skills that these new directors bring to the Board are instrumental to our achievement of synergies and global strategy going forward. The term “Business Combination” refers to both ADTRAN, Inc. and ADVA becoming subsidiaries of the Company through the Merger and the Exchange Offer, respectively, and the “closing of the Business Combination” refers to July 15, 2022. References in this Proxy Statement to “Adtran,” the “Company,” “we,” “our” and “us” refer to ADTRAN, Inc. prior to the MergerBusiness Combination and to ADTRAN Holdings, Inc. following the Merger.Business Combination.

If elected as a director at the Annual Meeting, each of the nominees would serve a one-year term expiring at the 20242025 Annual Meeting of Stockholders and until his or her successor has been duly elected and qualified. There are no family relationships among the directors, director nominees or the executive officers. Pursuant to the Company’s Director Resignation Policy, each of the director nominees is deemed to have agreed to promptly tender to the Chairman of the Board of Directors an irrevocable contingent resignation in the event that such director fails to receive a sufficient number of votes for re-election (a “majority against vote”). If any director nominee receives a majority against vote at the Annual Meeting, the Nominating and Corporate Governance Committee of the Board of Directors will recommend to the Board, and the Board will determine, whether to accept or reject the resignation tendered by such individual. Following the Board’s decision, the Company will file a Current Report on Form 8-K with the SEC in order to disclose the decision and, if applicable, the Board’s reasoning for rejecting the tendered resignation.

Our Bylaws provide that our Board consists of a single class of directors and that the terms of office of the directors is one year from the time of their election until the next annual meeting of stockholders and until their successors are duly elected and qualified. In addition, our Bylaws provide that, in general, vacancies on our Board may be filled by a majority of directors in office, even if less than a quorum, or by a sole remaining director (and not by the stockholders). Our Bylaws provide that the exact number of directors will be fixed from time to time by our Board pursuant to a resolution adopted by a majority of the whole Board.

Our Board of Directors seeks to ensure that the Board is composed of members whose experience, qualifications, attributes and skills, when taken together, will allow the Board to satisfy its oversight responsibilities effectively in light of the Company’s business and the laws and stock exchange rules that govern its affairs. We have no minimum qualifications for director candidates. In general, however, our Board will review and evaluate both incumbent and potential new directors in an effort to achieve diversity of skills and experience among our directors so that our Board has an effective mix of technical, financial, operating and management experience. Our Board has adopted corporate governance principles to guide the Company and the Board on various governance matters, and these principles task the Nominating and Corporate Governance

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We believe that our Board should be comprised predominantly of independent directors from diverse backgrounds external to the Company, but should nevertheless include the insight and judgment of our senior management. Our Board has no specific requirements regarding diversity but believes that its membership should reflect a diversity of experience, gender, race, ethnicity and age. Our Board is currently 33%25% female, 33%38% ethnically diverse, and 66%63% female or ethnically diverse. The following diversity statistics are reported in the standardized disclosure matrix that is required by the listing rules of the Nasdaq Stock Market (“Nasdaq”):

In assessing the experience, qualifications, attributes and skills that led our Nominating and Corporate Governance Committee and Board to conclude that each director has the appropriate qualifications to serve as a director of the Company, the Board focused on the information discussed in each of the director nominees’ individual biographies set forth on pages 1210 to 1613 of this Proxy Statement. In evaluating the suitability of the director nominees for re-election, our Nominating and Corporate Governance Committee also considered the director’s past performance, including attendance at meetings and participation in and contributions to the activities of the Board and its committees, as applicable.

Information Regarding the Nominees for Director

Set forth below is certain information regarding the nineeight nominees for director, including their ages, principal occupations or employment for at least the past five years, the length of their tenure as directors, and the names of other public companies in which such persons hold or have held directorships during the past five years. Additionally, information about the specific experience, qualifications, attributes or skills that led to our Board’s conclusion at the time of filing of this Proxy Statement that each person listed below should serve as a director is set forth below. The stock ownership with respect to each director nominee is set forth in the Security Ownership of Certain Beneficial Owners and Management table on page 8.6.

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Johnson Company. Mr. Stanton has served on the board of directors of a number of technology companies and is a past chairman of the board for both the Federal Reserve Bank of Atlanta’s Birmingham Branch and the Telecommunications Industry Association. He currently serveshas also served on the board of Cadence Bank (NYSE: CADE), formerly BancorpSouth Bank, since October 2015, and he is a director of the Economic Development Partnership of Alabama andAlabama. In addition, Mr. Stanton previously served as a director of the Huntsville Chamber of Commerce and has served on the board of BancorpSouth Bank (NYSE: BXS) since October 2015.Telecommunications Industry Association. Mr. Stanton holds a Bachelor of Science degree in Computer Engineering from Auburn University.

Mr. Stanton has been a member of our Board since September 2005. Mr. Stanton has been selected as a nominee for director because he is our Chief Executive Officer and has extensive knowledge of all facets of our Company and extensive experience in all aspects of our industry.

JOHANNA HEY, age 52, has served on the supervisory board of ADVA since June 2013 and became its chair in August 2022. She also currently serves on the supervisory board of the Gothaer Versicherungsbank VVaG and the Gothaer Finanzholding AG, as well as the supervisory boards of the University of Cologne Executive School GmbH and Flossbach von Storch AG.

Ms. Hey is a professor on tax law in Germany. Since 2006, she has been the director of the Institute for Tax Law at the University of Cologne and has served on the Scientific Advisory Board of the Federal Ministry of Finance of Germany. Since the winter term of 2002/2003, Ms. Hey has been the chair of corporate law at the Heinrich Heine University in Düsseldorf, Germany. From 2004 to 2012, Ms. Hey was a member of the committee and first Vice President of the German Association of University Professors. In 2010, she was announced as the head of science of the Berlin Finance and Taxation Institute and, in the same year, was elected to the Permanent Deputation of the Association of German Jurists. From 2011 to 2016, she was head of the Scientific Advisory Board of German Tax Lawyers. Since 2011, Ms. Hey has been a member of the Scientific Advisory Board of the Centre for European Economic Research.

Ms. Hey has been a member of our Board since the closing of the Business Combination in July 2022. Ms. Hey has been selected as a nominee for director because of her long-time service on the supervisory board of ADVA and her expertise in accounting and European and international tax law. She also has experience as a board member for various companies and organizations.

H. FENWICK HUSS, age 72,73, served as the Willem Kooyker Dean of the Zicklin School of Business at Baruch College, a senior college of The City University of New York, from July 2014 to December 2022. He also served as a tenured Professor in Baruch’s Stan Ross Department of Accountancy. He previously served as Dean of the J. Mack Robinson College of Business at Georgia State University from 2004 to 2014. Prior to his appointment as Dean, Dr. Huss was Associate Dean from 1998 to 2004 and Director of the School of Accountancy at Georgia State from 1996 to 1998, and on the faculty since 1989. He also served on the faculty of the University of Maryland as an assistant professor from 1983 to 1989 and is a visiting professor at the Université Paris 1 Pantheon-Sorbonne.

Dr. Huss has been a member of our Board since October 2002 and has served as our Lead Director since May 2015. Dr. Huss has been selected as a nominee for director because he brings the point of view of academia and, in particular, the information and new concepts that develop in the business school environment. Dr. Huss also has extensive experience and knowledge of financial accounting and corporate finance and management experience in the academic environment.

GREGORY MCCRAY, age 59,60, is an experienced executive with more than 30 years of business, marketing, sales, engineering, operations, mergers and acquisitions, management and international experience in

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years in the telecommunications industry. He has been a part of the Liberty family of companies since 2007, when he joined Liberty Global plc (NASDAQ: LBTYA) as its Senior Vice President and Chief Technology Officer. He most recently served as Executive Vice President and Chief Technology and Innovation Officer from 2007 to 2017. In this role, he was responsible for overseeing Liberty Global’s worldwide network, as well as Technology and Innovation operations, including Product Development, IT, Network Operations, Mobile Operations and Global Supply Chain functions. He was also responsible for Corporate Strategy and Venture Investments. Mr. Nair was an executive officer of Liberty Global and sat on Liberty Global’s Executive Leadership Team and the Investment Committee. Before joining Liberty Global, Mr. Nair served as Chief Technology Officer and Executive Vice President of AOL LLC, a global web services company. Prior to his role at AOL LLC, he spent more than 12 years at Qwest Communications International Inc., most recently as Chief Information Officer and Chief Technology Officer. Mr. Nair has a long history of working in the telephone, web world, and cable and media industries. He has served on the board of directors of Charter Communications, Inc. (NASDAQ: CHTR), a leading cable operator in the United States, since 2013, and on the board of Liberty Latin America since December 2017. He graduated from Iowa State University with a Bachelor of Science degree in Electrical Engineering and a Master of Business Administration degree. Mr. Nair holds a patent in systems development and is a Licensed Professional Engineer in Colorado.

Mr. Nair has been a member of our Board since February 2007. Mr. Nair has been selected as a nominee for director because he has extensive experience with the technologies that influence our industry and our markets and because he has management experience, particularly managing technical personnel, as well as his experience as a director of a publicly-held company.

BRIAN PROTIVA, age 58,59, has served as an executive of Egora Ventures AG, an investment company in Munich, Germany, since October 2023. Additionally, he led ADVA Optical Networking SEAdtran Networks as Chief Executive Officer since co-founding the company in 1994 through August 31, 2022. As the CEO, he was responsible for ADVA’sAdtran Networks’ overall strategy, M&A and human resources and he led every department at some point during his tenure. He fully

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NIKOS THEODOSOPOULOS, age 60,61, served as chairman of the supervisory board of ADVAAdtran Networks from January 2015 until August 2022. He also currently serves on the board of directors of Hercules Capital, Inc. and previously served on the boards of Arista Networks from March 2014 to June 2023 and Harmonic Inc.

In September from March 2015 to August 2022. Since August 2012, he foundedMr. Theodosopoulos has served as an independent director, advisor and currently serves asconsultant in the managing member oftechnology and financial services industries through his advisory firm, NT Advisors LLC, a technology consulting firm. Prior to founding NT Advisors, LLC,LLC. From 1994 through 2022, he was an equity research analyst, for 18 years primarily at UBS Group AG, covering the technology sector, where he eventually served as theManaging Director, Global Technology Strategist and Technology Sector Head of U.S. Equity Research. Prior to his career in investment banking, he spent 10 years at AT&T Network Systems and Bell Laboratories. He holds a Master in Business Administration from New York University, a Master of Science from Stanford University, and a Bachelor of Science from Columbia University.

Mr. Theodosopoulos has been a member of our Board since the closing of the Business Combination in July 2022. Mr. Theodosopoulos has been selected as a nominee for director because of his experience in the technology industry and his vast public board experience, in the technology industry including Chairman, Audit Committee Chair, and Compensation Committee Chair roles.

KATHRYN A. WALKER, age 63,64, has more than 30 years of experience in the communications industry. Since 2009, she has served as a managing director for OpenAir Equity Partners, a venture capital firm focusing on the wireless, communications and mobile Internet sectors. In addition, Ms. Walker is serving concurrently as Chief Technology Officer at Main Street Data, an agriculture data science company founded by OpenAir Equity Partners. Prior to joining OpenAir Equity Partners, Ms. Walker worked in a variety of roles at various subsidiaries of Sprint Corporation from 1985 to 2009, culminating in the position of Chief Information and Chief Network Officer at Sprint Nextel Corporation. She currently serves on the board of directors for SmartHome Ventures, on the Council of Trustees at South Dakota State University and as the Presidenta director of the

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CORPORATE GOVERNANCE

Governance Highlights

Our Board of Directors is committed to having sound corporate governance principles. Such principles are essential to running our business efficiently and to maintaining our integrity in the marketplace. The “Corporate Governance” section of this Proxy Statement describes our governance framework, which includes the following features:

Composition of the Board

Our Board seeks to ensure that the Board, as a whole, is strong in its collective knowledge of, and has a diversity of skills and experience with respect to, accounting and finance, management and leadership, vision and strategy, business operations, business judgment, crisis management, risk assessment, industry knowledge, corporate governance and global markets. As part of our annual Board self-evaluation process, the Board evaluates whether or not the Board as a whole has the appropriate mix of skills, experience, backgrounds and diversity in relation to the needs of the Company for the current issues facing the Company.

Directors to be nominated by the Company for election at the annual stockholders’ meeting are approved by the Board upon recommendation by the Nominating and Corporate Governance Committee. The Nominating and Corporate Governance Committee considers candidates for Board membership from recommendations by third-party executive search firms and candidates recommended by stockholders and by management, as well as recommendations from its committee members and other members of the Board. When the Nominating and Corporate Governance Committee reviews a potential new candidate, the Committee looks specifically at the candidate’s qualifications in light of the needs of the Board and the Company at that time given the then current mix of director attributes.

Process for Stockholders to Recommend Director Nominees

As provided in its charter, the Nominating and Corporate Governance Committee will consider potential director candidates submitted by stockholders. To recommend a nominee, a stockholder should write to the Nominating and Corporate Governance Committee at ADTRAN Holdings, Inc., Attn: Corporate Secretary,

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The Corporate Secretary will promptly forward these materials to the Chair of the Nominating and Corporate Governance Committee and the Chairman of the Board. The Nominating and Corporate Governance Committee may contact a recommended candidate to request additional information about the candidate’s independence, qualifications and other information that would assist the Committee in evaluating the candidate. The Charter of the Nominating and Corporate Governance Committee and the Company’s Corporate Governance Principles set forth factors that the Board and the Nominating and Corporate Governance Committee may consider in evaluating a director nominee, regardless of the recommending party.

In addition to submitting nominations in advance to the Nominating and Corporate Governance Committee for consideration, a stockholder also may nominate persons for election to the Board of Directors in person at a stockholders meeting. Section 3.4 of the Company’s Bylaws provides for procedures pursuant to which stockholders may nominate a candidate for election as a director of the Company. Furthermore, stockholders who intend to solicit proxies in support of director nominees other than the Company’s nominees must provide notice to the Company that complies with the informational and timing requirements of Rule 14a-19 under the Exchange Act to comply with the SEC’s universal proxy rules, in addition to satisfying the requirements under our Bylaws. The chairperson of the meeting shall have the power to determine and declare to the meeting whether or not a nomination was made in accordance with the procedures set forth in our Bylaws and, if the chairperson determines that a nomination is not in accordance with the procedures set forth in the Bylaws, to declare that the defective nomination will be disregarded. A copy of our Bylaws is available in the “Corporate Governance” section of our website at https://investors.adtran.com. Printed copies of the Bylaws may also be obtained at no charge by writing to the Corporate Secretary at ADTRAN Holdings, Inc., Attn: Corporate Secretary, 901 Explorer Boulevard, Huntsville, Alabama 35806.

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Board, Committee and Individual Director Evaluation Program

Pursuant to the Corporate Governance Principles, the Board and each of its committees conduct an annual evaluation of its performance, led by the Nominating and Corporate Governance Committee. The evaluation is intended to determine whether the Board and its committees are functioning effectively and fulfilling the requirements set forth in the Corporate Governance Principles or the committee’s charter, as applicable. Beginning in 2018, the evaluations also included self-evaluations pursuant to which the directors were asked to examine their own contributions to the Board or committee, as appropriate, and potential areas of improvement. The Nominating and Corporate Governance Committee formalized the following self-evaluation program, with the goal of placing additional emphasis on improvements to processes and effectiveness:

				Board and Committee members complete self-evaluations: These questionnaires are completed individually in order to encourage honest feedback from the directors.

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responsibilities as a director. Members of the Audit, Compensation and Nominating and Corporate Governance Committees must also meet applicable independence tests of Nasdaq and the SEC. Additionally, the charter of the Environmental, Social and Governance (“ESG”) Committee requires that its members also be independent under Nasdaq’s listing standards.

The Board has reviewed a summary of directors’ responses to a questionnaire asking about their relationships with the Company, as well as material provided by management related to transactions, relationships or arrangements between the Company and the directors and parties related to the directors. Following this review, the Board determined that sevensix of the nineeight directors (Ms. Hey, Dr.(Dr. Huss, Mr. McCray, Mr. Nair, Ms. Rice, Mr. Theodosopoulos and Ms. Walker) are independent. Additionally, the Board determined that each current member of the Audit, Compensation, Nominating and Corporate Governance, and ESG Committees, as well as each director who served on any of the committees during 2022,2023, also satisfies the independence tests referenced above. In determining the independence of Mr. Nair, who serves as President and Chief Executive Officer of Liberty Latin America Ltd., the Board considered that we have maintained customer relationships with several Liberty Latin America affiliates for some time. Our sales to the Liberty Latin America affiliates are in the ordinary course of business and relate to arms’ length purchase orders submitted by Liberty Latin America affiliates. The amounts received by us from Liberty Latin America affiliates in each of the past three years were less than 1.0% of our consolidated gross revenues in each such year and less than 0.1% of Liberty Latin America’s operating costs and expenses. Liberty Latin America is not considered one of our significant customers. Accordingly, it was determined that Mr. Nair does not have a direct or indirect material interest in the Company’s relationship with Liberty Latin America.

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Each committee operates under a written charter adopted by the Board, which are available in the “Corporate Governance” section of our website at https://investors.adtran.com. The Nominating and Corporate Governance Committee is responsible for evaluating the membership of the committees and making recommendations to the Board regarding the same, which it does annually following a review of the Board’s current competencies. This periodic review of each director’s specific skills and experience allows the Nominating and Corporate Governance Committee to ensure that the committees are organized for optimal effectiveness.

The Board met six15 times in 2022.2023. None of the incumbent directors attended less than 75% of the aggregate of (a) the total number of meetings held in 20222023 of the Board while he or she was a director and (b) the total number of meetings held in 20222023 of all committees of the Board on which he or she served. Absent extenuating circumstances, directors are expected to participate in annual meetings of the Company’s stockholders, and all of our directors serving at that time attended the 20222023 Annual Meeting of Stockholders, except Mr. Nair.Stockholders.

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Risk Management and Cybersecurity Oversight

Enterprise Risk Management

Our management continually monitors the material risks facing the Company, including financial risk, strategic risk, operational risk, and legal and compliance risk. The Board of Directors is responsible for overseeing management’s identification and management of, and planning for, those risks. The Board has delegated to certain committees oversight responsibility for those risks that are directly related to their areas of focus. The Audit Committee is responsible for coordinating the Board’s oversight of the Company’s risk management program, including the process by which management assesses, prioritizes and manages the Company’s material risks. The Audit Committee also oversees the major financial, data security and enterprise

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Corporate Social Responsibility and Sustainability

As we follow our vision to “enable a fully connected world,” corporate social responsibility (CSR) and environmental, social and governance (ESG) matters are important to us. As more people are connected, work and life can be accomplished using fewer resources. On the journey to our vision, we must continue to be a responsible corporate citizen of the world. We have established ESG and sustainability programs and policies that encompass the elements of Environmental, Health & Safety, Ethics, Labor, and Management Systems in alignment with the ISO 26000 Guidelines. We are committed to operating in full compliance with the laws, rules and regulations of all the countries in which we operate. Adtran recognizes the Responsible Business Alliance (RBA) Code of Conduct (the “Code”) and actively pursues conformance to it and its standards in accordance with our management systems. Adtran further recognizes the Code as a total supply chain initiative.

We have an established Sustainability Working Group Committee comprised of members of senior management in the areas of engineering, sales, research and development, strategic planning, software and solutions quality, corporate compliance, and supplier quality engineering and environmental, among others. This working group meets monthly in order to establish our sustainability strategy and monitor progress toward these goals. Additionally, the newly-formed ESG Committee of the Board has been formally tasked with overseeing management’s efforts related to the long-term sustainable growth of the Company, including considering the social and environmental goals of the Company. We use the GRI standards frameworkEuropean Sustainability Reporting Standards (ESRS) for our ESG reporting, and these standards support our ESG risk, materiality and context assessments. Highlights of our current practices in these areas are described below.

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Equity Ownership Requirement for Non-Employee Directors

In March 2020, the Board of Directors adopted stock ownership guidelines for non-employee directors effective January 1, 2020. The Outside Director Stock Ownership Guidelines require each director to hold shares of the Company’s common stock with a value equal to at least three times the director’s regular annual cash retainer. Directors have until the later of January 1, 2025 and five years from the date of such director’s election to meet the ownership requirement. The minimum number of shares to be held by a director will be calculated during the first calendar quarter of each fiscal year based on the director’s annual cash retainer in effect as of December 31^st of the preceding year. The value of shares held by a director will be deemed to be the greater of (i) fair market value on the last trading day of the immediately preceding calendar year and (ii) fair market value

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EXECUTIVE COMPENSATION

Compensation Discussion and Analysis

Executive Summary

This Compensation Discussion and Analysis is designed to provide our stockholders with an explanation of our executive compensation philosophy and objectives, our 20222023 executive compensation program and the compensation paid by us to the following named executive officers (or “NEOs”): Thomas R. Stanton, Chief Executive Officer (“CEO”), Michael K. Foliano,; Ulrich Dopfer, Senior Vice President, of Finance, Chief Financial Officer, and Corporate Secretary Ronald D. Centis, Senior Vice President of Global Operations, Raymond Harris, Senior Vice President and Chief Information Officer, Treasurer;James D. Wilson, Jr., Chief Revenue Officer, andOfficer; Christoph Glingener, Chief Technology Officer of the Company and former CEO of Adtran Networks; and Michael K. Foliano, Former Senior Vice President of Finance, Chief ExecutiveFinancial Officer, of ADVA.Treasurer and Secretary (who retired from the Company effective June 28, 2023).

Compensation Philosophy

The guiding principles of our executive compensation program are to:

We design our executive compensation packages in a manner that incorporates these principles. We also evaluate the compensation packages to ensure they will help us encourage executive management to deliver strong performance results in the compensation year under consideration and motivate management to realize our strategic initiatives within the immediate, near and long-term time frames our directors and management have developed. Additionally, we consider various market performance metrics in order to put the executive compensation program in context, including the performance of the Company in prior periods, the performance of the industry and our competitors in those periods, and total stockholder return (“TSR”), particularly as relative to our peer companies over those periods.

We also maintain a positive working environment that provides intangible benefits to our executives and encourages longevity. Combining compensation with a desirable working environment allows us to maintain a compensation program that generally provides overall compensation to our executive officers that is approximately at the median when compared to companies with which we compete for talent.

We consider the feedback that we receive from stockholders regarding our compensation packages, principles and process, including the results of the annual vote on the compensation of our NEOs (often referred to as the “say-on-pay” vote). Although the “say-on-pay” vote is advisory and non-binding, the Compensation Committee considers the outcome of the vote as part of its executive compensation planning process. At the 2022 Annual Meeting of Stockholders, 98.41% of the votes cast on the “say-on-pay” proposal voted to approve the Company’s compensation of our NEOs. Since 2011, all of the Company’s “say-on-pay” votes have been favorable, by percentages ranging from 96.28% to 99.49%. We believe that this high level of stockholder support indicates that stockholders believe the compensation program should continue to emphasize the performance, alignment and retention objectives established by the Compensation Committee and described herein.

Compensation in Context: Discussion of 20222023 Financial Results and Operating Activities

Aligning executive compensation with stockholder interests is a primary consideration in determining our executive compensation program. Accordingly, we believe that Company performance and stockholder

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Financial Results:

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Financial Results:

All of this was accomplished while adaptingdespite customer spending continuing to be negatively impacted by excess inventory and the weakened macroeconomic environment related to continued elevated interest rates and ongoing global pandemic and historic supply chain constraints.inflationary pressures. Despite these challenges, we continue to see increasing investment from both public and private sectors in fiber-based broadband connectivity and capacity upgrades in the network infrastructure in our primary growth markets in the U.S. and Europe. The growth in fiber broadband is further increasing the demand for cloud-managed mesh Wi-Fi solutions and software solutions to improve in-home wireless connectivity while

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The compensation of our NEOs is comprised of the following elements:

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Role of the Compensation Committee and Management

Under our Compensation Committee’s Charter, the Compensation Committee has the power and duty to discharge our Board’s responsibilities related to compensation of our executive officers, within guidelines established by the Board. The Compensation Committee reviews and approves compensation, including base salary, annual incentive awards and equity awards, for the Chief Executive Officer and our other executive officers. The Compensation Committee also makes recommendations to the Board regarding our incentive compensation plans and equity plans and approves equity grants. The Committee has the authority to review and approve annual performance goals and objectives for our Chief Executive Officer and to set his compensation based on an evaluation of his performance conducted by the Board under the direction of the Lead Director. The Committee is also responsible for reviewing and approving executive officers’ compensation and establishing performance goals related to their compensation.

At the beginning of each calendar year, our Compensation Committee establishes the structure of the Company’s incentive compensation programs for the current year, including setting the performance goals for the Variable Incentive Cash Compensation Plan (the “VICC”) programs and the standards for measuring achievement of those goals, approves any increases in executive salaries or other compensation, approves the annual equity grants, and recommends plan changes, if any, for submission to our stockholders at the annual meeting. Mid-year, the Compensation Committee generally reviews our compensation programs and makes recommendations to the Board regarding outside director compensation and, as necessary throughout the year, approves any equity awards and/or compensation for newly hired or promoted executives. Our Compensation Committee historically has met in the latter part of each calendar year to determine and approve annual equity awards. However, following the Business Combination, the Compensation Committee determined it was appropriate to transition to making annual equity grants in the first quarter of each calendar year, such that the Committee did not make its annual equity grants in 2022 but instead granted such awards in early 2023. This change is to better align the combined companies, provide grants to a broader base, align long-term incentive performance periods with Adtran’s fiscal year, and time the equity and cash compensation with the annual review by our compensation consultants.

In fulfilling its fiduciary duties pertaining to the Company’s employee retirement benefit plans, our Compensation Committee considers the information and advice it receives from a committee of Company personnel it established, chaired by the Chief Financial Officer, which reviews and monitors the performance of retirement plan investments and assets, the performance and fees of the Company’s retirement plan custodians and administrators, and the recommendations of third-party registered fiduciary advisors of our benefits plans, a process which includes periodicquarterly meetings with these third parties. ADVAAdtran Networks has a similar committee with employee representation responsible for overseeing ADVA’ssuch entity’s benefit and retirement plans.

Our Chief Executive Officer works closely with the Compensation Committee to maintain an open dialogue regarding the Compensation Committee’s goals, progress towards achievement of those goals and expectations for future performance. The Chief Executive Officer updates the Compensation Committee regularly on results and various compensation issues. Our Chief Executive Officer also provides the Committee, and in particular, the Committee Chair, with recommendations regarding compensation for our executive officers other than himself. The Compensation Committee considers the recommendations from the Chief Executive Officer when approving pay changes for the executives other than the Chief Executive Officer. The Compensation Committee has delegated to the Chief Executive Officer the authority to approve the base salaries and incentive compensation of non-executive employees, as well as equity grants to such individuals, subject to pre-approved limits and terms and conditions. In part because the Chief Executive Officer works closely with the Committee throughout the year, the Committee is in a position to evaluate his performance and make its own determinations regarding appropriate levels of compensation for the Chief Executive Officer.

Role of the Compensation Consultant

Our Compensation Committee has the authority to retain and terminate any outside advisors, such as compensation consultants. From 2016 through 2021,Starting in 2022, the Committee engaged Willis Towers Watson,Pay Governance LLC, an

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The Compensation Committee believes comparison to these companies is appropriate, given the limited number of comparable companies and direct competition with these peers for executive talent. The Compensation Committee also references various peer, industry and market compensation data when evaluating the appropriateness of the Company’s compensation program, including the compensation arrangements of our NEOs.

The Compensation Committee reviews the types of services provided by Pay Governance and all fees paid for those services on a regular basis. Neither Pay Governance nor any of its affiliates provided additional services to the Company or any of its affiliates in 2022,2023, other than the advice provided by Pay Governance to the Compensation Committee on director compensation and the advice provided to the Company on pension plan management, company insurance and employee health insurance. As required by rules adopted by the SEC under the Dodd-Frank Act, the Compensation Committee assessed all relevant factors and determined that the work of Pay Governance did not raise any conflict of interest in 2022.2023. In making this determination, the Compensation Committee considered all relevant factors, including those set forth in Rule 10C-1(b)(4)(i) through (vi) under the Exchange Act.

Benchmarking and Individual Considerations

The Company reviews compensation data for similar positions from Proxy peers, as well as from the telecom and networking industry and the broader general industry. We generally seek to provide our executives with base salaries and target bonus and long-term incentive opportunities that are positioned around the median of competitive practice in order to assist in attracting and retaining talented executives and to further motivate and reward our NEOs for sustained, long-term improvements in the Company’s financial results and the achievement of long-term business objectives. We recognize, however, that benchmarking may be subject to variation from one year to the next. As a result, we also use Company and individual performance in determining the appropriate compensation opportunities for our NEOs.

Our Compensation Committee also focuses on establishing and maintaining a compensation structure that is internally consistent and provides appropriate compensation for our executives in relation to one another. Consequently, the Compensation Committee does not focus on any particular benchmark to set executive compensation. Instead, we believe that a successful compensation program requires the application of judgment

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The Compensation Committee does not assign relative weights or rankings to these factors. Our allocation of compensation between cash and equity awards, our two principal forms of compensation, is based upon our historical practice and our evaluation of the cost of equity awards, as discussed in more detail below. An important part of this evaluation is the Committee’s consideration of the goals of the several initiatives undertaken in the execution of the Company’s business plan and each executive’s past and expected future contributions toward those goals at the time of setting executive compensation packages.

Risk Assessment

The Compensation Committee has evaluated the Company’s compensation program, plans and practices for all of its employees as they relate to risk management and risk-taking initiatives to ascertain if they serve to incent risks which are “reasonably likely to have a material adverse effect” on the Company. As a result of this process, the Compensation Committee concluded and informed the Board of Directors that any risks arising from these programs, plans and practices are not reasonably likely to have a material adverse effect on the Company.

The Compensation Committee has attempted to establish compensation programs that value current goals along with long-term growth. While the use of short-term cash incentive opportunities creates the potential for short-term risk-taking, the Committee believes that this risk is more than offset by the fact that a short-term cash incentive is only one of three primary elements of the overall compensation program and has governance features that are aligned with market best practice (e.g., maximum payout opportunity of 200% of target). Additionally, the Committee has the ability to utilize discretion to reduce the amount of a cash incentive award if an executive officer takes unnecessary risks. The Committee has concluded that the two other primary elements of our total compensation program – base salaries and long-term equity awards – are either risk neutral or help lower risk. Annual salaries are based on a number of factors, including the individual’s position and responsibility within our Company and performance in that position. The longer-term equity awards incentivize executives to focus on improving the Company and its operations rather than taking risks for short-term gain.

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Our “Say-on-Pay” Results from Last Year and Our Response

Stockholder Letter from the Compensation Committee

Dear Stockholders,

I hope this letter finds you well. I am writing to address the outcome of the stockholder vote on the Company’s executive compensation plan taken at the 2023 Annual Meeting of Stockholders, commonly referred to as “Say-on-Pay.” The Compensation Committee is committed to maintaining a strong and transparent dialogue with our stockholders, and we take all concerns and feedback seriously.

First and foremost, we would like to express our gratitude for your active participation and engagement in this critical aspect of our corporate governance. Your votes and opinions play a vital role in shaping our compensation policies, and your involvement underscores the importance of responsible stewardship.

It is with regret that we acknowledge the outcome of the Say-on-Pay vote in 2023, which indicated that a majority of our stockholders (53%) did not support our executive compensation plan. We understand that this result reflects concerns about various aspects of our compensation program, including its alignment with performance, competitive benchmarks, and stockholder interests.

The Compensation Committee and the Board of Directors are deeply committed to addressing these concerns and ensuring that our executive compensation practices are both competitive and aligned with the long-term interests of our stockholders. To address these concerns, we are taking the following steps:

We want to assure you that our commitment to responsible corporate governance remains unwavering. We understand that our compensation programs must be designed to attract, retain, and motivate talented executives while also being accountable to our stockholders. We believe that, by addressing the concerns raised by this vote, we can enhance the alignment of our executive compensation practices with the long-term success of the Company.

Your trust in our Company is invaluable, and we remain dedicated to earning and preserving that trust. We are committed to working diligently to address the issues raised by the failed Say-on-Pay vote and to ensuring that our compensation practices are consistent with the best interests of our stockholders. You will see our progress in this Compensation Discussion and Analysis section.

Thank you for your continued support and engagement. We look forward to ongoing dialogue and collaboration as we strive to improve our executive compensation practices.

Sincerely,

Nikos Theodosopoulos

Chair of the Compensation Committee, on behalf of the Compensation Committee

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Stockholder Outreach and Response

Considering the Say-on-Pay vote result from the 2023 Annual Meeting of Stockholders, the Compensation Committee commissioned an outreach program to identify and assess the items of concern for our stockholders. This process included meetings with interested stockholders to identify and catalog their concerns, followed by an assessment of the most prevalent issues to determine what actions may be required. The program was broad-based, focusing on institutional investors and supplemented with feedback from shareholder advisory services. We contacted 30 investors holding 73.6% of our outstanding shares and received feedback from 20 investors holding 64.0% of our outstanding shares, as illustrated below:

The stockholder outreach meetings were attended at various times by the Chair of our Compensation Committee, our Chief Financial Officer, and our Vice President, Investor Relations, and from the investor side, the meetings were attended by Managing Directors, Fund Managers, Corporate Governance Teams, Stewardship Teams, and Proxy Review Teams.

The investors provided feedback on the following items, in order of most cited to least cited, and here is what we have done in response:

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The Committee also extended the measurement period for the short-term cash incentive program from quarterly performance periods to a half-year performance period in the second half of 2023, and currently intends to use a one-year measurement period going forward.

We also engaged with and received feedback from two of the largest and most reputable shareholder advisory services. Their feedback was closely aligned with what we heard from our shareholders during the outreach process.

In light of the slowing of customer demand during 2023 and the effect on revenues, on December 1, 2023, the Committee approved reductions to the base salaries of certain officers and other highly-compensated employees that are expected to extend until July 31, 2024. The CEO’s base salary was reduced by 50%, other NEO salaries were reduced by 25%, and other highly-compensated individuals were reduced between 5% and 15% depending on their current base salary. These reductions to the NEO salaries are reflected in the Summary Compensation Table on page 47.

In summary, the Compensation Committee is committed to maintaining a strong and transparent dialogue with our stockholders, and the Committee takes concerns and feedback seriously. The Committee has developed and implemented a process to collect and assess stockholder feedback and has addressed this feedback through changes to the compensation system where it makes sense. The Committee will continue to review feedback and best practices in the future to ensure alignment.

Elements of 20222023 Executive Compensation

Our executive compensation program consists of base salary; short-term cash incentives, including those under our VICC program, a sales incentive arrangement for our Chief Revenue Officer, and occasional one-time performance bonuses for certain executives; and long-term equity incentives in the form of time-based and performance-based equity. Historically, the Compensation Committee has granted time-based RSUs that vest ratably over four years and market-based PSUs that the NEOs are eligible to earn based on Company

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base salary compensation, and adjusts it when warranted, based on the Company’s financial performance, the individual’s position and responsibility within our Company and performance in that position, the importance of the executive’s position to our business, and the compensation of other executive officers of the Company with comparable qualifications, experience and responsibilities. The Committee also generally takes into account the range of salaries of executive officers with comparable qualifications, experience and responsibilities at other companies with which we compete for executive talent.

At a meeting of the Compensation Committee held on January 21, 2022,20, 2023, the Compensation Committee reviewed the base salaries of our executive officers, taking into account the considerations described above. The Committee approved the following base salaries for the NEOs:

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The Compensation Committee established a target for theeach Company Performance Measure for the first quarter of 20222023 at its meeting on January 21, 202220, 2023 and then established a target for each subsequentthe second quarter withinof 2023 at the first two weeks of each quarter. At each quarterlyCommittee’s meeting theon April 14, 2023. The Compensation Committee certified the level of achievement for each of these two quarters at the prior quarter and approvedCommittee’s subsequent quarterly meeting. At the payoutCompensation Committee’s meeting on July 14, 2023, the Committee determined it was appropriate to establish a target for each Company Performance Measure for the second half of the corresponding cash award amount.2023. In order to be eligible to receive any bonus amount for a fiscal quarter,each of the first two quarters or the second half of 2023, the Company must have achieved in such quarter both (i)time period a prescribed minimum threshold level for theeach Company Performance Measure and (ii) a threshold level of revenue.Measure.

Each NEO was granted a target bonus amount (in dollars and as a percentage of base salary), with the actual incentive earned to be based on the two Company Performance Measure.Measures. In determining the target bonus amount for each NEO, the Compensation Committee considered, among other things, the executive’s responsibilities and opportunity to influence the achievement of the Company Performance Measure,Measures, as well as the executive’s prior contributions to the Company’s performance. The Compensation Committee set theEach NEO’s target goal forbonus amount (in dollars and as a percentage of base salary) was as follows: Mr. Stanton – $1,400,000 (140%), Mr. Dopfer – $246,000 (60%), Mr. Wilson – $162,029 (40%), Dr. Glingener – $210,000 (60%), and Mr. Foliano – $360,110 (80%). Mr. Foliano forfeited his 2023 cash incentive award in connection with his retirement from the Company effective June 28, 2023.

The bonus awards for 2023 were based on the two Company Performance Measure for each quarter at a level that would require strong performance and execution.Measures described above:

Payouts for performance between the threshold and maximum levels were subject to non-linearinterpolation. Failure to meet the minimum performance threshold corresponding to a specific performance measure in a fiscal quarter (or half year) would have resulted in the participant not receiving any portion of the payout award related to such quarter.performance measure for the quarter (or half year). In no event could a participant receive more than 100% of the target bonus related to each Company Performance Measure and, therefore, not more than 200% of the target bonus.bonus award. The Compensation Committee believes that it is appropriate to establish a maximum payout that any participant could receive under the bonus programprograms in order to avoid an excessive payout should Company results or individual performance significantly exceed expectations.

2023 Actual Bonus Program Results

As the performance thresholds for the 2023 bonus program were not achieved during either of the first two quarters of 2023 or the second half of 2023, none of the NEOs received a payout under the 2023 bonus program.

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2022 Actual Bonus Program Results

The individual target bonus awards, including as a percentage of salary, for the NEOs and the amounts earned and paid each quarter based on the level of achievement of the Company Performance Measure were as follows:

20222023 Sales Incentive Arrangement for Chief Revenue Officer

The Company has in place a sales incentive program for certain of its employees whose focus is on sales. Mr. Wilson, our Chief Revenue Officer, began participating in this program in 2020. The Compensation Committee believes that sales incentives should be an important element of Mr. Wilson’s cash compensation, as they tie a portion of his pay directly to his success in his area of responsibility. As such, he receives a portion of his cash compensation in sales incentives, which is consistent with our historical practice and our understanding of the standard practice in the market for sales-oriented executives. The Compensation Committee approved a target sales incentive for Mr. Wilson in 20222023 of $75,013$81,014 based on input from the CEO, which target is a percentage of direct gross shipments to customerssales revenue in 2022.2023. The Compensation Committee and CEO set the gross shipment performance target at a level that it believes was reasonably difficult to achieve given the business environment at the time the target was established. The sales incentive arrangement further allows Mr. Wilson to earn up to 180% of his target amount if certain gross direct shipments exceed the defined performance target. If Mr. Wilson’s achievement exceeds 180% of the performance target amount for the year, these payments are withheld until the next year and paid out in equal quarterly installments. Mr. Wilson must be an active employee or contractor of the Company at the time of payment in order to receive such amounts. If his employment by or service to the Company is terminated for any reason prior to payment, certain unpaid amounts will be forfeited. The Company’s CEO has discretion to determine that a “windfall” has occurred and decrease the amount paid to Mr. Wilson, and incentive compensation may be reduced or eliminated in order to reflect a number of actions that may be taken by a customer, including canceling or reducing an order or not paying an invoice. Based on this arrangement, Mr. Wilson earned a sales incentive of $68,436$59,228 in 2022.

2022 One-Time Retention Bonus

Additionally, the Committee decided at its meeting on October 14, 2022 that it was in the best interests of the Company and its stockholders to grant a one-time bonus to Mr. Foliano in order to reward and recognize his significant efforts toward completing the Company’s acquisition and integration of ADVA during 2022 and encourage his retention. Based on these considerations, Mr. Foliano was awarded a cash bonus of $500,000, payable following December 31, 2022 assuming his continued employment on such date, and is reflected in the “Bonus” column of the Summary Compensation Table on page 48. The bonus was paid to Mr. Foliano in January 2023. Due to the aforementioned one-time award and an accompanying increase in his VICC target for 2023 (from 60% to 80%), Mr. Foliano did not receive equity awards, like the rest of the NEOs, in the first quarter of 2023.

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The Compensation Committee’s process for determining the amounts of the incentive equity awards begins with a consideration of the overall dollar level of value that the Committee determines is appropriate, taking into account the estimated expense to the Company of the awards and the earnings per share impact of that expense. WeThe Committee typically establishestablishes an internal target for the aggregate expense from Company-wide equity awards, which, based on our review of industry data as discussed above, we believe is at the low end of the expense levels incurred by our competitors. This dollar value is then translated into a number of shares of ourthe Company’s common stock based on the current range of the stock’s market price. Based on this process, the Committee established a pool of up to 583,310 RSUs and PSUs to be granted to all participants in the 2020 Employee Plan for the 2023 Annual Equity Awards. The 218,810 RSUs and PSUs granted to the NEOs in 2023 are included in this total. The Compensation Committee allocated the pool of RSUs and PSUs among the different functions throughout the Company based on the importance and performance of the function and considerations such as retention and competitive compensation levels. The Committee also considered the recommendations of our CEO with respect to the awards to other executives and employees, as well as individual and Company performance during 2021 and 2022.

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Pursuant to earned market-based PSUs, a corresponding number of shares is issued at the end of the three-year performance period, and after that time there is no additional holding period for the shares that are issued. Under the award agreements and Mr. Stanton’s Employment Agreement, a portion of the granted market-based PSUs also vest and become issuable upon the termination of a recipient’s employment or upon a change inof control of the Company, as discussed in more detail below under the heading “Potential Payments Upon Termination or Change inof Control.” ThePrior to the suspension of the Company’s dividend, the recipients of the market-based PSUs under the award agreements receivereceived dividend credits based on the shares of common stock underlying the market-based PSUs. The dividend credits are vested, earned and distributed in cash upon issuance of the shares pursuant to the earned market-based PSUs. Recipients may choose to defer shares issued pursuant to earned PSUs under the Deferred Compensation Plan instead of receiving the shares at the time they are entitled to distribution of the shares.

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Integration Awards

On March 1, 2023, the Compensation Committee established an “Integration Bonus Plan” consisting of a combination of performance-based PSUs and cash bonus award amounts (together with the PSUs, the “Integration Awards”). Under the Integration Bonus Plan, certain key employees of the Company, including the NEOs (other than Mr. Foliano as described below), are eligible to earn the Integration Awards over a performance period beginning on the grant date (for Messrs. Stanton and Wilson, March 1, 2023, and for Mr. Dopfer and Dr. Glingener, May 24, 2023) and ending on December 31, 2024, based on the achievement of cost savings targets related to the Business Combination during such period. The Compensation Committee chose the performance measure of “Company Synergy Achievement” in order to incentivize the participants to drive cost savings and expected synergies following the closing of the Business Combination, and it approved a target level of synergies against which the Company’s non-GAAP expenses will be measured. For purposes of measuring performance, the Company’s GAAP expenses will be adjusted for restructuring expenses; acquisition-related expenses, amortizations and adjustments; stock-based compensation expense; amortization of actuarial pension losses and the impact of equity market changes on deferred compensation expenses; non-operating income; and any other exclusions adopted by the Company. The Compensation Committee set the synergies performance target at a level that it believes was reasonably difficult to achieve given the business environment at the time the target was established.

If the Company Synergy Achievement over the performance period reaches the performance levels noted below, the participants will be entitled to a corresponding number of shares of the Company’s common stock under the PSUs:

If the threshold level of Company Synergy Achievement is reached, the participants are also eligible to receive a cash award up to 66% of their base salary (as of the grant date) based on the percentage of individual objectives related to cost savings achieved by each participant, as determined by the Compensation Committee. If the target level of Company Synergy Achievement is achieved and all of the individual objectives are achieved, the participants will earn a maximum amount under the Integration Bonus Plan equal to 132% of their base salary, as reflected below:

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