UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

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REGENXBIO Inc.

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REGENXBIO Inc.
9804 Medical Center Drive
Rockville, MD 20850

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

Dear Stockholder:

You are cordially invited to attend the Annual Meeting of Stockholders (the “Annual Meeting”) of REGENXBIO Inc., a Delaware corporation (the “Company”). The Annual Meeting will be held on May 31, 2024, at 9:00 a.m. local time at the Company’s offices located at 9804 Medical Center Drive, Rockville, Maryland 20850 for the following purposes:

Only stockholders of record at the close of business on April 1, 2024 are entitled to notice of, and to vote at, the Annual Meeting or any adjournment or postponement thereof. A complete list of such stockholders will be available for inspection at the Company’s offices in Rockville, Maryland at the Annual Meeting and during normal business hours for a period of 10 days prior to the Annual Meeting.

Your vote is important. Whether or not you plan to attend the Annual Meeting in person, please submit your proxy by telephone or over the internet, or by completing, signing, dating and returning your proxy card or voting instruction form so that your shares will be represented at the Annual Meeting. Instructions for voting are described in the Company’s proxy statement for the Annual Meeting, Notice of Internet Availability of Proxy Materials and proxy card.

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting of Stockholders to be held on May 31, 2024:

The Company’s Notice of Annual Meeting, Proxy Statement and Annual Report on Form 10‑K for the fiscal year ended December 31, 2023 are available at www.proxyvote.com.

This Proxy Statement is first being mailed to the stockholders of the Company on or about April 4, 2024.

TABLE OF CONTENTS

REGENXBIO Inc.

9804 Medical Center Drive

Rockville, MD 20850

PROXY STATEMENT

This Proxy Statement is furnished in connection with the solicitation of proxies to be voted at the 2024 Annual Meeting of Stockholders (the “Annual Meeting”) of REGENXBIO Inc., which will be held on May 31, 2024, at 9:00 a.m. local time at the Company’s offices located at 9804 Medical Center Drive, Rockville, Maryland 20850.

When this Proxy Statement refers to “REGENXBIO,” the “Company,” “we,” “us” or “our,” it is referring to REGENXBIO Inc.

We are making this Proxy Statement and our Annual Report on Form 10‑K for the fiscal year ended December 31, 2023 (the “Annual Report”) available to stockholders at www.proxyvote.com. On or about April 4, 2024, we will begin mailing to our stockholders a Notice of Internet Availability of Proxy Materials (the “Notice”) containing instructions on how to access and review this Proxy Statement and the Annual Report. The Notice also instructs you how you may submit your proxy over the internet or via telephone. If you would like to receive a printed copy of our proxy materials, you should follow the instructions for requesting those materials included in the Notice.

PROXY STATEMENT EXECUTIVE SUMMARY

This summary highlights information contained elsewhere in this Proxy Statement. This summary does not contain all of the information you should consider. Please read the entire Proxy Statement carefully before voting.

Voting Overview and Vote Recommendations of the Board - Items of Business

Election of Directors: Please vote “For” each nominee (page 6)

Ratification of Appointment of Independent Registered Public Accounting Firm: Please vote “For” (page 21)

Advisory Vote on Executive Compensation: Please vote “For” (page 24)

About REGENXBIO

We are a leading clinical-stage biotechnology company seeking to improve lives through the curative potential of gene therapy. Our investigational gene therapies are designed to deliver functional genes to address genetic defects in cells, enabling the production of therapeutic proteins or antibodies that are intended to impact disease. Through a single administration, gene therapy could potentially alter the course of disease significantly and deliver improved patient outcomes with long-lasting effects.

Our investigational gene therapies use adeno-associated virus ("AAV") vectors from our proprietary gene delivery platform, which we call our NAV® Technology Platform. AAV vectors are non-replicating viral delivery vehicles that are not known to cause disease. Our NAV Technology Platform consists of exclusive rights to a large portfolio of AAV ("NAV Vectors") vectors, including commonly used AAV8, and AAV9 vectors. We believe this platform forms a strong foundation for our current clinical-stage programs and with our ongoing research and development, we expect to continue to expand our platform and pipeline of potential AAV vector-based gene therapies. We refer to commercial and investigational AAV vector-based gene therapies as AAV Therapeutics.

Business Highlights

In 2023, we made significant progress toward our clinical development and business objectives, including the following achievements:

Corporate Governance Highlights

Our commitment to effective corporate governance is illustrated by the following practices:

Sustainability Highlights

Investor Engagement in 2023

Following our 2023 annual meeting, as part of our off-season stockholder engagement efforts, our leadership team reached out to engage with 18 stockholders representing approximately 74% of our outstanding common stock to discuss the progress of our clinical trials, our business strategy, our financial performance and strategic initiatives and our corporate governance. We also provided these stockholders with an overview of the overall state of the AAV gene therapy industry.

PROPOSAL 1:

ELECTION OF DIRECTORS

Under our Restated Certificate of Incorporation (the “Certificate of Incorporation”) and Amended and Restated Bylaws ("the Bylaws"), the Board is divided into three classes of roughly equal size. The members of each class are elected to serve a three-year term with the term of office of each of the three classes ending in successive years. Pursuant to our Bylaws, the Board has fixed the current number of directors at nine. George Migausky, Kenneth T. Mills and David C. Stump, M.D., are the three Class III directors whose terms expire at this Annual Meeting. The Board has nominated Messrs. Migausky, Mills and Dr. Stump (collectively, the “nominees” and each, a “nominee”) to serve until the 2027 annual meeting of stockholders or until their successors are duly elected and qualified, or until their earlier death, resignation, retirement, disqualification or other removal. Each of the nominees was recommended for election by the Nominating and Corporate Governance Committee, and each such recommendation was approved unanimously by the Board.

Shares represented by signed proxy cards will be voted on Proposal 1 “For” the election of Messrs. Migausky, Mills and Dr. Stump to the Board at the Annual Meeting, unless otherwise marked on the card. If any of the nominees becomes unavailable for election as a result of an unexpected occurrence, shares represented by proxy will be voted for the election of a substitute nominee designated by the current Board, unless otherwise marked on the card. Messrs. Migausky, Mills and Dr. Stump have each agreed to serve as a director if elected. We have no reason to believe that any of the nominees will be unable to serve if elected.

Certain information about each of the nominees is furnished below, including their business experience, public company director positions held currently or at any time during the last five years and the experience, qualifications, attributes or skills that caused the Nominating and Corporate Governance Committee and the Board to determine that the nominees should continue to serve as directors.

Our directors have a diverse set of skills and experience on the board, including:

George Migausky has been a Director since September 2021. Mr. Migausky has more than 30 years of experience in the life sciences industry, having served as Chief Financial Officer for several public biopharmaceutical and clinical diagnostic companies. From April 2017 to September 2017, Mr. Migausky served as interim Chief Financial Officer for Ocular Therapeutix, Inc., a biopharmaceutical company. Prior to that, he served as Chief Financial Officer of Dyax Corp., a biopharmaceutical company, from August 2008 through the company’s acquisition by Shire plc in January 2016. Prior to that, Mr. Migausky served as Chief Financial Officer of Wellstat Management Company, a biotechnology company, from 2007 to 2008, and Chief Financial Officer of IGEN International, Inc., a biotechnology company, and BioVeris Corporation, a diagnostics company, from 1986 through their acquisitions by F. Hoffman LaRoche in 2004 and 2007, respectively. Mr. Migausky has served as a director at Immunovant, Inc., a publicly held biopharmaceutical company, since December 2019. He has also served as a trustee at the Massachusetts Eye and Ear Institute since 2015. Mr. Migausky previously served as a director at Dimension Therapeutics, Inc. from June 2015 through the company’s acquisition by Ultragenyx Pharmaceutical Inc. in November 2017, and at Abeona Therapeutics Inc. from June 2020 to September 2020 and at Hyperion Catalysis International, a privately held electrical manufacturing company, from 2008 to August 2022. He received a B.S. from Boston College and an M.B.A. from Babson College. Mr. Migausky has specific attributes that qualify him to continue to serve as a member of the Board, including his significant experience in executive leadership positions in the life sciences industry and serving on the boards of directors and audit committees of publicly traded biopharmaceutical companies.

Kenneth T. Mills has been our President, Chief Executive Officer and Director since March 2009. Mr. Mills was with FOXKISER, most recently as a Partner, from January 2007 to January 2015. Mr. Mills was previously the Chief Financial Officer and

Vice President of Business Development at Meso Scale Diagnostics, a life sciences company, from January 2004 to December 2006 and was part of the original management team that established the company’s operations and financing strategy. From March 1997 to December 2003, Mr. Mills was employed at IGEN International, Inc., a biotechnology company, where he served as Director of Business Development up through the company’s acquisition by Roche. Mr. Mills received an S.B. in Chemistry from the Massachusetts Institute of Technology. Mr. Mills’ qualifications to continue to serve as a member of the Board include his extensive experience as an executive in the gene therapy and biotechnology industries, including as President and Chief Executive Officer of our Company, his prior service as a senior-level executive in both early stage and mature biotechnology companies and his demonstrated business judgment.

David C. Stump, M.D., has been a Director since October 2015. From November 1999 to December 2012, Dr. Stump was with Human Genome Sciences, Inc., a biopharmaceutical company, as Executive Vice President, Research and Development from May 2007 to December 2012, Executive Vice President, Drug Development from December 2003 to May 2007 and Senior Vice President, Drug Development from November 1999 to December 2003. Prior to joining Human Genome Sciences, Dr. Stump held roles of increasing responsibility at Genentech, Inc., a biopharmaceutical company, from 1989 to 1999, including Vice President, Clinical Research and Genentech Fellow. Prior to joining Genentech, Dr. Stump was an Associate Professor of Medicine and Biochemistry at the University of Vermont. Dr. Stump has served as a director at MacroGenics, Inc., a publicly held biopharmaceutical company, since September 2013. He also currently serves on the board of trustees of Earlham College. Dr. Stump previously served as a director at Sunesis Pharmaceuticals, Inc. from June 2006 to February 2021, Portola Pharmaceuticals, Inc. from September 2015 to July 2020 and Dendreon Corporation, a biotechnology company, from June 2010 to June 2015. Dr. Stump holds an A.B. from Earlham College and an M.D. from Indiana University and completed his residency and fellowship training in internal medicine, hematology, oncology and biochemistry at the University of Iowa. Dr. Stump has specific attributes that qualify him to continue to serve as a member of the Board, including his substantial medical and scientific background and expertise, his extensive experience in research and development and operations in the biotechnology industry and his prior service on public company boards.

Vote Required

Directors are elected by a plurality of the votes cast at the Annual Meeting. The three nominees receiving the highest number of “For” votes will be elected. Abstentions and broker non-votes will have no effect on the outcome of the election of directors at the Annual Meeting.

Recommendation of the Board

The Board unanimously recommends a vote “For” each director nominee.

Continuing Directors Not Standing for Election

Certain information about those directors whose terms do not expire at the Annual Meeting is furnished below, including their business experience, public company director positions held currently or at any time during the last five years and the experiences, qualifications, attributes or skills that caused the Nominating and Corporate Governance Committee and the Board to determine that the directors should serve as one of our directors. The term of the Class I directors will expire at the 2025 annual meeting of stockholders, and the term of the Class II directors will expire at the 2026 annual meeting of stockholders.

Class I Directors (Terms Expire in 2025)

Allan M. Fox has been the Chairman of the Board since July 2020 and a Director since February 2009. Mr. Fox is the founding partner of FOXKISER, a firm committed to the strategic development of transformative innovations from biomedical research, which was formed in September 1986. Mr. Fox specializes in identifying business opportunities and improving competitive market positions. Through FOXKISER, he has participated in the formation and development of numerous ventures in the public and private sectors, including the founding of REGENXBIO and Dimension Therapeutics, Inc. Before forming FOXKISER, Mr. Fox co-led the establishment of the Washington office of the law firm of Kaye Scholer. While in the public sector, Mr. Fox served as Chief of

Staff and Chief Legislative Assistant to U.S. Senator Jacob K. Javits of New York. He also served as Chief Counsel to the United States Senate Health and Scientific Research Subcommittee, chaired by Senator Edward M. Kennedy. Mr. Fox was a Fellow in Law, Science and Medicine at Yale Law School where he received an LL.M. degree. Mr. Fox also holds a J.D. and B.A. from Temple University. Mr. Fox has specific attributes that qualify him to continue to serve as a member of the Board, including his broad experience in providing strategic advice to and investing in biotechnology companies throughout their life cycles, his expertise in identifying business opportunities, his deep experience with REGENXBIO since the time of its founding and his current and prior service on boards of directors.

Alexandra Glucksmann, Ph.D., has been a Director since May 2018. Dr. Glucksmann has served as CEO and President of Sensorium Therapeutics, a privately held biotechnology company, since December 2023 and has served as a director at Scenic Biotech BV, a privately held biotechnology company, since September 2017. From April 2018 to November 2022, Dr. Glucksmann served as the President and Chief Executive Officer and a director at Cedilla Therapeutics, Inc., a privately held biotechnology company, and from October 2017 to March 2018, Dr. Glucksmann was an Entrepreneur-in-Residence at Third Rock Ventures, LLC, a privately held healthcare venture firm, where she focused on company formation. She was also a founding employee of Editas Medicine, Inc., a publicly held biotechnology company, and served as its Chief Operating Officer from October 2013 to March 2017. Prior to that, Dr. Glucksmann was a founding employee of Cerulean Pharma Inc., a publicly held biotechnology company, and served as its Senior Vice President of research and business operations from September 2006 to June 2013. From August 2006 to May 2015, she served as a director at Taconic Biosciences, Inc. Dr. Glucksmann received a B.S. in Bacteriology from the University of Wisconsin-Madison and a Ph.D. in Molecular Genetics and Cell Biology from the University of Chicago, and she completed her postdoctoral fellowship at the Massachusetts Institute of Technology. Dr. Glucksmann’s qualifications to continue to serve as a member of the Board include her extensive experience in senior management positions at biotechnology companies, particularly her experience in the formation and development of biotechnology companies.

Jennifer Zachary has been a Director since June 2022. Ms. Zachary currently serves as the Executive Vice President and General Counsel of Merck & Co., Inc. In this role, she serves as a legal advisor to Merck’s directors and executives, leads the company’s office of general counsel and sets the company’s global legal strategy. She is also responsible for the company’s compliance, global safety and environment, and global security functions. Prior to joining Merck, Ms. Zachary was a partner at the international law firm Covington & Burling, LLP. She practiced in the area of pharmaceutical and medical device regulatory law and advised a wide range of manufacturers and trade associations on compliance with government requirements for the development, manufacture and sale of their products. Prior to that, Ms. Zachary served as an Associate Chief Counsel for enforcement at the FDA and as a Special Assistant U.S. Attorney in the Civil Division of the U.S. Attorney’s Office for the District of Columbia. Ms. Zachary holds a B.S./B.A. in biology and chemistry from Arizona State University and a J.D. from Harvard Law School. Ms. Zachary has specific attributes that qualify her to continue to serve as a member of the Board, including her government service related to health care and regulatory compliance, experience in senior management positions at a large biopharmaceutical company and a global law firm, and her strong knowledge of strategic, legal and regulatory issues.

Class II Directors (Terms Expire in 2026)

Jean Bennett, M.D., Ph.D., has been a Director since September 2021. Dr. Bennett has been the F.M. Kirby Emeritus Professor of Ophthalmology at the Perelman School of Medicine at the University of Pennsylvania since July 2021, where she was previously a professor for 17 years. She also served as director of the Center for Advanced Retinal and Ocular Therapeutics at the University of Pennsylvania from July 2014 to June 2023. In addition to Dr. Bennett’s positions at the University of Pennsylvania, she has been an Investigator at the Center for Cellular and Molecular Therapeutics at The Children’s Hospital of Philadelphia for more than a decade. She also co-founded life science companies Spark Therapeutics (acquired by Roche), GenSight Biologics, Limelight Bio and Opus Genetics. Dr. Bennett has published or contributed to more than 120 peer-reviewed publications on gene therapy, including her pioneering work on gene therapy delivery of RPE65, which was foundational to the approval of Luxturna, the first gene therapy product approved by the U.S. Food and Drug Administration (the “FDA”). Dr. Bennett received a B.S. in Biology from Yale University, a Ph.D. in Zoology and Cell Biology from the University of California, Berkeley and an M.D. from Harvard University. She also completed postdoctoral fellowships in Radiobiology and Environmental Health at the University of California, San Francisco, Human Genetics at Yale School of Medicine and Development Genetics at The Johns Hopkins University School of Medicine. Dr. Bennett’s work as a leading molecular genetics researcher and her past experience in drug development, provides her with deep medical and scientific experience and with life sciences expertise, particularly in the field of retinal gene therapy.

A.N. “Jerry” Karabelas, Ph.D., has been the Lead Independent Director since July 2020 and a Director since May 2015. Dr. Karabelas has been a Venture Partner at Apple Tree Partners, a life sciences venture capital firm, since January 2021, prior to which he was a Partner at Care Capital, LLC (“Care Capital”), a life sciences venture capital firm, from December 2001 to December 2020. Before joining Care Capital, Dr. Karabelas was Chairman at Novartis BioVentures Fund, which is owned by Novartis AG (“Novartis”), a provider of capital for life sciences companies across the biotech, medical devices and diagnostics industries, prior to which he was the Chief Executive Officer of Novartis Pharma AG, which is also owned by Novartis. Before joining Novartis, Dr. Karabelas was Executive Vice President, Worldwide Pharmaceuticals of SmithKline Beecham, where he was responsible for U.S. and European operations, regulatory and strategic marketing. Dr. Karabelas also serves as a director at Braeburn Pharmaceuticals, Inc., a

privately held pharmaceutical company, since September 2015. He previously served as director at Bausch Health Companies from 2016 until 2023, Chairman at Polyphor AG, a pharmaceutical company, from June 2013 to November 2019 and Inotek Pharmaceuticals Corporation from July 2012 to June 2016. In connection with his work at Care Capital, Dr. Karabelas previously served on numerous boards of directors of pharmaceutical and therapeutics companies, including Renovo, plc, Vanda Pharmaceuticals, Inc. and NitroMed, Inc. Dr. Karabelas also previously served as Chairman at SkyePharma, plc and Human Genome Sciences. Dr. Karabelas received a B.S. from the University of New Hampshire and a Ph.D. from the Massachusetts College of Pharmacy. Dr. Karabelas's senior management positions at commercial and development-stage biopharmaceutical companies, strong knowledge of strategic and regulatory issues, his insight into international operations and his international perspective on the life sciences industry and healthcare related issues provides him with deep executive leadership, medical, life sciences, regulatory, international and commercial expertise.

Daniel Tassé has been a Director since August 2016. Mr. Tassé has served as the Chief Executive Officer and a director of DBV Technologies SA, a publicly held biopharmaceutical company, since November 2018. From March 2016 to March 2019, he was the Chairman of Alcresta Therapeutics, Inc. (“Alcresta”), a privately held biopharmaceutical company, and from March 2016 to November 2018, he was the Chairman and Chief Executive Officer of Alcresta. Mr. Tassé previously served as a director at Indivior PLC, from August 2014 to May 2021, Bellerophon Therapeutics, Inc. from December 2013 to May 2019 and HLS Therapeutics Inc. from March 2018 to March 2019. Prior to the acquisition of Ikaria Inc. (“Ikaria”) by Mallinckrodt Pharmaceuticals in April 2015, Mr. Tassé was President, Chief Executive Officer and Chairman of Ikaria and served as the Interim Chief Executive Officer and President of Bellerophon from February 2014 to June 2014. Previously, Mr. Tassé was the General Manager of the Pharmaceuticals and Technologies Business Unit of Baxter International, Inc. and Vice President and Regional Director for Australasia at GlaxoSmithKline plc. Mr. Tassé was a member of the Health Section Governing Board of the Biotechnology Industry Organization, where he participated on the bioethics, regulatory environment and reimbursement committees. Additionally, Mr. Tassé was a member of the board of directors of the Pharmaceutical Research and Manufacturers of America, where he participated on the FDA and biomedical research committee. Mr. Tassé received a B.Sc. in Biochemistry from the University of Montreal. Mr. Tassé has an extensive track record of business building in the healthcare industry, a strong background in commercial operations, global management experience and a detailed knowledge of the life sciences industry, which provides him with a breadth of executive leadership, life sciences and international experience.

CORPORATE GOVERNANCE

Our Board is responsible for oversight of the management of the Company. In carrying out its responsibilities, the Board selects and monitors our management team, provides oversight of our financial reporting processes and determines and implements our corporate governance policies.

Corporate Responsibility

The Company seeks to enhance stockholder value while embodying its core values of Trust, Accountability, Perseverance and Innovation (our “Core Values”). As part of our Core Values the Company engages in the following areas to further our environmental, social and governance strategy:

Environmental Footprint

The Company is cognizant of its impact on the wider environment. In recognition of that impact, the Company's Rockville, Maryland headquarters is Leadership in Energy and Environmental Design Gold certified. Furthermore the Company is engaging in multiple initiatives that are designed to improve manufacturing yields and is measuring its baseline emissions to reduce waste. In recognition of those efforts, in June of 2023 the Company received the Outstanding Efforts in Waste Reduction and Recycling Award highlighting the Company’s waste reduction efforts. The award is given to businesses that have undertaken exemplary efforts to develop, expand, or enhance their waste reduction and recycling programs to reduce waste and recycle more.

Diversity, Equity and Inclusion

The Company strongly supports efforts to promote diversity, equity and inclusion (“DEI”), as we believe that a diverse, equitable and inclusive culture fosters innovation, which is integral to our mission. We are firmly committed to providing equal opportunity in all aspects of employment and have established a DEI Champion Group to further our DEI initiatives. The DEI Champion Group is supported by an executive sponsor and through activities and programs facilitates employee engagement to increase understanding and celebration of the Company's diverse workforce. Our commitment to DEI is also reflected in our workforce population that includes 57% identifying as female and 44% from historically underrepresented minority populations. We have also emphasized DEI as part of our company culture, as set out in our Code of Business Conduct and Ethics, and we are determined to support further progress in this area.

Corporate Governance Guidelines

The Board has adopted corporate governance guidelines, which, along with our Certificate of Incorporation and Bylaws, and the charters of the committees of the Board, provide the framework for our corporate governance. Our current corporate governance guidelines can be found, together with other corporate governance information, in the corporate governance section of our website at www.regenxbio.com. The Board also evaluates the charters of its committees from time to time, as appropriate.

Code of Business Conduct and Ethics

We maintain a code of business conduct and ethics that qualifies as a “code of ethics” under Item 406 of the Securities and Exchange Commission’s (the “SEC”) Regulation S-K and applies to each of our directors, officers and employees, including our principal executive officer, principal financial officer, principal accounting officer and controller, or persons performing similar functions. The code of business conduct and ethics addresses various topics, including: (1) compliance with applicable laws, rules and regulations; (2) conflicts of interest; (3) public disclosure of information; (4) insider trading; (5) corporate opportunities; (6) competition and fair dealing; (7) gifts; (8) discrimination, harassment and retaliation; (9) health and safety; (10) record keeping; (11) confidentiality; (12) protection and proper use of company assets; (13) prevention of corruption; and (14) the reporting of illegal and unethical behavior.

The code of business conduct and ethics is available in the corporate governance section of our website at www.regenxbio.com. Any amendment or waiver of the “code of ethics” provisions of the code of business conduct and ethics for an executive officer or director may be granted only by the Board or a committee thereof and must be timely disclosed as required by applicable law. We intend to satisfy the disclosure requirements regarding any such amendment or waiver applicable to any principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions, in a current report filed with the SEC on Form 8-K or on our website at www.regenxbio.com.

Director Independence

As required under Nasdaq listing standards, a majority of the members of a listed company’s board of directors must qualify as “independent,” as affirmatively determined by the board of directors. Consistent with these regulations, after review of all relevant transactions or relationships between each director, or any of such director’s family members, and the Company, its senior management and its independent registered public accounting firm, the Board has determined that all of our current directors are independent directors within the meaning of applicable Nasdaq listing standards, except for Kenneth T. Mills, our President and CEO, and Allan M. Fox.

Information Regarding the Board of Directors and its Committees

As required under Nasdaq listing standards, our independent directors meet in regularly scheduled executive sessions at which only independent directors are present.

The Board has an Audit Committee, a Compensation Committee and a Nominating and Corporate Governance Committee. The following table provides membership and meeting information for each of the Board committees during 2023:

Below is a description of each committee of the Board. The Board has determined that each member of the Audit, Compensation and Nominating and Corporate Governance Committees meets applicable rules and regulations regarding “independence” and that each such member is free of any relationship that would interfere with his or her individual exercise of independent judgment with regard to the Company.

Audit Committee

The Audit Committee of the Board oversees the quality and integrity of the Company’s financial statements and other financial information provided to the Company’s stockholders, the retention and performance of the Company’s independent accountants, the effectiveness of the Company’s internal controls and disclosure controls, and the Company’s compliance with ethics policies and SEC and related regulatory requirements. Pursuant to the Audit Committee charter, the functions of the Audit Committee include, among other things:

Our Audit Committee charter can be found in the corporate governance section of our website at www.regenxbio.com.

Three directors currently comprise the Audit Committee: Mr. Migausky (the Chair of the Audit Committee), Ms. Zachary and Dr. Stump. The Audit Committee met six times during 2023.

All members of our Audit Committee meet the requirements for financial literacy under the applicable rules and regulations of the SEC and Nasdaq. The Board has determined that Mr. Migausky is an “audit committee financial expert,” as defined by applicable SEC rules, and has the requisite financial sophistication as defined under the applicable Nasdaq listing standards.

The Board annually reviews the Nasdaq listing standards definition of independence for Audit Committee members and has determined that all members of our Audit Committee are independent (as independence is currently defined in applicable Nasdaq listing standards and Rule 10A-3 promulgated under the Securities Exchange Act of 1934, as amended (the “Exchange Act")).

Compensation Committee

The Compensation Committee of the Board reviews and approves the design and philosophy of, assesses the effectiveness of, and administers executive compensation programs for officers and employees, including our equity incentive plans. Pursuant to the Compensation Committee charter, the functions of the Compensation Committee include, among other things:

In accordance with Nasdaq listing standards and our Compensation Committee charter, the Board has granted our Compensation Committee the authority and responsibility to retain or obtain the advice of compensation consultants, legal counsel and other compensation advisers, the authority to fund such advisers, and the responsibility to consider the independence factors specified under applicable law and any additional factors the Compensation Committee deems relevant. Our Compensation Committee charter can be found in the corporate governance section of our website at www.regenxbio.com.

Three directors currently comprise the Compensation Committee: Mr. Tassé (the Chair of the Compensation Committee) and Drs. Glucksmann and Karabelas. The Compensation Committee met seven times during 2023.

The Board has determined that all members of the Compensation Committee are independent (as independence is currently defined in the Nasdaq listing standards). In addition, each of our directors serving on our Compensation Committee satisfies the heightened independence standards for members of a compensation committee under Nasdaq listing standards, and is a non-employee director, as defined pursuant to Rule 16b-3 promulgated under the Exchange Act.

Our President and CEO often participates in the Compensation Committee’s meetings. He does not participate in the determination of his own compensation or the compensation of directors. Our President and CEO makes recommendations to the Compensation Committee regarding the amount and form of the compensation of the other executive officers and key employees, and he often participates in the Compensation Committee’s deliberations about the compensation of such individuals. Our Executive Vice President ("EVP"), Chief People Officer and our EVP, Chief Legal Officer also regularly participate in the Compensation Committee’s meetings, but they do not participate in the determination of the amount or form of the compensation of executive officers or directors.

The Compensation Committee has retained Willis Towers Watson as its independent compensation consultant since April 2019. In connection with the 2023 compensation paid by the Company, Willis Towers Watson provided the Compensation Committee with data about the compensation paid by our peer group of companies, as described below, and other employers who compete with the Company for executives, updated the Compensation Committee on new developments in areas that fall within the Compensation Committee’s remit and was available to advise the Compensation Committee regarding its responsibilities. The compensation consultant serves at the pleasure of the Compensation Committee rather than the Company, and the consultant’s fees are approved by the Compensation Committee. The Compensation Committee assessed the independence of Willis Towers Watson pursuant to applicable SEC rules and Nasdaq listing standards and concluded that Willis Towers Watson was independent under such standards and that their work did not raise any conflict of interest.

Nominating and Corporate Governance Committee

The Nominating and Corporate Governance Committee of the Board identifies, evaluates and recommends nominees to the Board and committees of the Board, conducts searches for appropriate directors, and evaluates the performance of the Board, its committees and management against their duties and responsibilities relating to corporate governance. Pursuant to the Nominating and Corporate Governance Committee charter, the functions of the Nominating and Corporate Governance Committee include, among other things:

Our Nominating and Corporate Governance Committee charter can be found in the corporate governance section of our website at www.regenxbio.com.

Two directors currently comprise the Nominating and Corporate Governance Committee: Dr. Stump (the Chair of the Nominating and Corporate Governance Committee) and Dr. Bennett. The Nominating and Corporate Governance Committee met four times during 2023.

The Nominating and Corporate Governance Committee believes that candidates for director should have certain minimum qualifications, including being able to read and understand basic financial statements and having a general understanding of the Company’s industry. The Nominating and Corporate Governance Committee also considers other factors it deems appropriate, including, but not limited to:

In conducting this assessment, the Nominating and Corporate Governance Committee also considers diversity, age, skills, and such other factors as it deems appropriate given the then-current needs of the Board and the Company, to maintain a balance of knowledge, experience and capability.

In the case of incumbent directors whose terms of office are set to expire, the Nominating and Corporate Governance Committee reviews such directors’ overall service to the Company during their term, including the number of meetings attended, level of participation, quality of performance, and any other relationships and transactions that might impair such directors’ independence.

We believe that each of our directors brings a strong background and set of skills to our Board, giving the Board, as a whole, an appropriate balance of diversity, knowledge, experience, attributes, skills and expertise. In addition, seven of our nine directors are independent under Nasdaq standards (Mr. Mills, our President and CEO, and Mr. Fox being the exceptions) and our Nominating and Corporate Governance Committee believes that all nine directors are independent of the influence of any particular stockholder or group of stockholders whose interests may diverge from the interests of our stockholders as a whole. We believe that our directors have a broad range of personal characteristics including leadership, management, pharmaceutical, gene therapy business, marketing and financial experience and abilities to act with ethics and integrity, with sound judgment and collegially, to consider strategic proposals, to assist with the development of our strategic plan and oversee its implementation, to oversee our risk management efforts and executive compensation and to provide leadership, to commit the requisite time for preparation and attendance at Board and committee meetings and to provide required expertise on Board committees.

In evaluating director candidates, our Nominating and Corporate Governance Committee has reviewed the experience, qualifications, attributes and skills of our directors and nominees, including those identified in the biographical information set forth above in the section entitled “Election of Directors.” The Nominating and Corporate Governance Committee believes that the members of the Board offer insightful and creative views and solutions with respect to issues facing the Company. In addition, the Nominating and Corporate Governance Committee also believes that the members of the Board function well together as a group. The Nominating and Corporate Governance Committee believes that the above-mentioned attributes and qualifications, along with the leadership skills and other experiences of the members of the Board described in further detail above under the section entitled “Election of Directors,” provide the Company with the perspectives and judgment necessary to guide the Company’s strategies and monitor their execution.

When there is a vacancy on the Board, the Nominating and Corporate Governance Committee uses its network of contacts to compile a list of potential candidates, but may also engage, if it deems it appropriate, a professional search firm. The Nominating and Corporate Governance Committee conducts any appropriate and necessary inquiries into the backgrounds and qualifications of possible candidates after considering the function and needs of the Board. The Nominating and Corporate Governance Committee

meets to discuss and consider such candidates’ qualifications and then selects a nominee for recommendation to the Board by majority vote.

Director Qualifications and Diversity

The Board believes that it is important that its members represent diverse viewpoints, with a broad array of experiences, professions, skills and backgrounds that, when considered as a group, provide a sufficient mix of perspectives to allow the Board to best fulfill its responsibilities to the long-term interests of our stockholders. The attributes required of Board members, as a whole, may include (i) various and relevant career experience, (ii) relevant skills, such as an understanding of our business and industry, (iii) financial expertise, including the ability to read and understand basic financial statements, (iv) diversity (including, but not limited to, race, ethnicity, national origin, gender, and LGBTQ+ status) and (v) local and community ties.

The Board believes that gender diversity and racial and ethnic diversity are important in providing diverse viewpoints. Our commitment to that belief is reflected in the composition of our Board, with three of the past four new members elected by the Board, being women and we anticipate that generally before the 2025 annual meeting or as soon as reasonably practicable to seek to further increase the Board’s diversity through the appointment of an additional member of our Board. The Company considers diversity more broadly than is defined in Nasdaq standards. The Company and the Board are committed to continue seeking director candidates who would further increase the Board’s diversity. That commitment is reflected in the Director Nomination Policy included in our Nominating and Corporate Governance Committee's charter. For further details regarding our current Board diversity, please refer to the Board diversity matrix set forth below. In addition, our Board diversity matrix for 2023 is available in our proxy statement for the 2023 annual meeting, which is available on our website and at www.sec.gov:

Board Renewal

The Board believes it is important to have experienced directors with a deep understanding of the Company’s business as well as newer directors who bring fresh perspectives to the Board. In its efforts to identify potential director candidates, the Board and the Nominating and Corporate Governance Committee consider the input from the directors’ self-evaluation process to identify the backgrounds and expertise that are desired and the future needs of the Board in light of anticipated director retirements or

resignations. The Board’s ongoing assessment of its collective skills, experience and expertise resulted in the recruitment of four new independent directors within the past six years.

Our recruiting process typically involves either engaging a search firm or having a member of the Board or the Nominating and Corporate Governance Committee contact a prospect to gauge the prospect’s interest and availability. A candidate will then meet with several members of the Board and then meet with members of the Company’s management as appropriate. At the same time, the Board or the Nominating and Corporate Governance Committee and the search firm will contact references for the prospect. A background check is completed before a final recommendation is made to the Board to appoint a candidate to the Board.

Meetings of the Board

The Board met six times during 2023. Each director attended 75% or more of the aggregate of the meetings of the Board and of the committees on which he or she served, held during the period for which he or she was a director or committee member.

Directors are encouraged, but not required, to attend our annual meetings of stockholders. All of the then-continuing directors attended our 2023 annual meeting of stockholders.

Compensation Committee Interlocks and Insider Participation

None of the members of the Compensation Committee is or has ever been an officer or employee of the Company. No executive officer of the Company serves as a member of the board of directors or compensation committee of any other entity that has one or more executive officers serving as a member of our Board or our Compensation Committee.

Performance Evaluations of the Board of Directors and its Committees

In accordance with our corporate governance guidelines and the Nominating and Corporate Governance Committee charter, the Board, with the assistance of the Nominating and Corporate Governance Committee, evaluates the performance of the Board, its committees and each individual director on an annual basis. Each member of the Board conducts an annual self-evaluation for the purpose of determining whether the Board and its committees are functioning optimally. As part of this process, each director considers the effectiveness of the Board and each committee on which the director serves. The results of the evaluations are discussed at subsequent meetings of the Board and its committees.

Director Nominations

The Nominating and Corporate Governance Committee will consider director candidates recommended by stockholders and evaluate them using the same criteria as candidates identified by the Board or the Nominating and Corporate Governance Committee. The Nominating and Corporate Governance Committee may also take into consideration the number of shares of the Company’s common stock held by the recommending stockholder and the length of time that those shares have been held. To recommend a director candidate for consideration by the Nominating and Corporate Governance Committee, a stockholder must submit the recommendation in writing to the Company, including the following information:

Recommendations and the information described above should be sent to our Corporate Secretary at REGENXBIO Inc., 9804 Medical Center Drive, Rockville, Maryland 20850, Attention: Corporate Secretary.

Once a person has been identified by the Nominating and Corporate Governance Committee as a potential director candidate, the Nominating and Corporate Governance Committee may: collect and review publicly available information regarding the person to assess whether the person should be considered further; request additional information from the candidate and the proposing stockholder; contact references or other persons to assess the candidate; and conduct one or more interviews with the candidate. The Nominating and Corporate Governance Committee may consider that candidate in light of information regarding any other candidates that the Nominating and Corporate Governance Committee may be evaluating at that time, as well as any relevant director search criteria. The evaluation process generally does not vary based on whether or not a candidate is recommended by a

stockholder; however, as stated above, the Nominating and Corporate Governance Committee may take into consideration the number of shares held by the recommending stockholder and the length of time that those shares have been held.

In addition to recommending director candidates to the Nominating and Corporate Governance Committee, stockholders may also nominate candidates for election to the Board at an annual meeting of stockholders. For more information, see “Questions and Answers About the Proxy Materials and Voting—May I propose actions for consideration at next year’s annual meeting of stockholders or nominate individuals to serve as directors?”

Separation of Chairman of the Board and Chief Executive Officer Roles

The Board separates the positions of Chairman of the Board and CEO. Separating these positions allows our CEO to focus on our day-to-day business, while allowing the Chairman of the Board to lead the Board in its fundamental role of providing advice to and independent oversight of management. The Board recognizes the time, effort, and energy that the CEO is required to devote to his position in the current business environment, as well as the commitment required to serve as our Chairman of the Board, particularly as the Board’s oversight responsibilities continue to grow. We believe that having separate positions and having an outside director serve as Chairman of the Board is the appropriate leadership structure for the Company at this time.

Lead Independent Director

As the Chairman of the Board is not an independent director, the Board has appointed a Lead Independent Director to provide leadership for our independent directors. The Lead Independent Director has a clearly defined set of responsibilities and provides significant independent Board leadership. Dr. Karabelas has served as our Lead Independent Director since July 1, 2020. During Dr. Karabelas’s nearly nine years of service on our Board, he has consistently demonstrated strong leadership skills in addition to his strong knowledge of strategic and regulatory issues. The independent directors of the Board are confident in Dr. Karabelas’s ability to continue to serve as Lead Independent Director.

The position of Lead Independent Director has a clear mandate, significant authority and well-defined responsibilities under our corporate governance guidelines. These responsibilities include:

Risk Oversight

The Board has responsibility for the oversight of the Company’s risk management processes and, either as a whole or through its committees, regularly discusses with management our major risk exposures, their potential impact on our business and the steps we take to manage them. The risk oversight process includes the Board receiving regular reports from Board committees and members of senior management to enable the Board to understand and evaluate the Company’s risk identification, risk management and risk mitigation strategies with respect to areas of potential material risk, including operations, finance, legal, regulatory, strategic, reputational, information and cyber security, human capital, environmental and social risk. The oversight of risk within the Company is an evolving process requiring the Company to continually look for opportunities to further embed systematic enterprise risk management into ongoing business processes within the Company.

The Board is responsible for overseeing information security risk, and management reports to the Board regarding our assessment of information security risk, among other risks we face, on a periodic basis. Management monitors our information security systems to identify and mitigate any related risks, and we do not believe we have experienced any material cyber breaches. We maintain cybersecurity insurance coverage and we continue to invest in data protection and information technology, including providing an information security training and compliance program to our employees. Periodically, the Audit Committee reviews our

policies with respect to risk assessment, risk management, loss prevention and regulatory compliance. The Audit Committee reviews information regarding liquidity and operations, and oversees our management of financial risks. Oversight by the Audit Committee includes direct communication with our external auditor, and discussions with management regarding significant risk exposures and the actions management has taken to limit, monitor or control such exposures. The Compensation Committee is responsible for assessing whether any of our compensation policies or programs has the potential to encourage excessive risk-taking and conducts a compensation risk assessment on an annual basis. The Nominating and Corporate Governance Committee manages risks associated with the independence of the Board, corporate governance practices, and potential conflicts of interest. While each committee is responsible for evaluating certain risks and overseeing the management of such risks, the entire Board is regularly informed through committee reports about such risks. Matters of significant strategic risk are considered by the Board as a whole.

Communications with the Board

The Board is interested in receiving communications from stockholders and other interested parties. These parties may contact any member of the Board or any committee of the Board, the non-employee directors as a group or the chairperson of any committee. In addition, the Audit Committee is interested in receiving communications from employees and other interested parties regarding accounting, internal controls or auditing matters. Any such correspondence should be addressed to the appropriate person or persons, either by name or title, and sent to our Corporate Secretary at REGENXBIO Inc., 9804 Medical Center Drive, Rockville, Maryland 20850, Attention: Corporate Secretary. The Corporate Secretary will review all such communications, but may, in his or her sole discretion, disregard any communication that he or she believes is not related to the duties and responsibilities of the Board. If deemed an appropriate communication, the Corporate Secretary will share the communication with the applicable director or directors.

Following our 2023 annual meeting, as part of our off-season stockholder engagement efforts, our leadership team reached out to engage with 18 stockholders representing approximately 74% of our outstanding common stock to discuss the progress of our clinical trials, our business strategy, our financial performance and strategic initiatives and our corporate governance. We also provided these stockholders with an overview of the overall state of the AAV gene therapy industry.

DIRECTOR COMPENSATION

Our Board determines the compensation of our non-employee directors in conjunction with recommendations made by the Compensation Committee. We use a combination of cash and share-based compensation to attract and retain qualified candidates to serve on the Board. Kenneth T. Mills, our President and CEO and a member of the Board, did not receive any compensation from us during our fiscal year ended December 31, 2023 for his service as a director and is not included in the 2023 Director Compensation Table below.

Fees Earned or Paid in Cash

In 2023, pursuant to our compensation program for non-employee directors, each member of the Board who was not an employee received the following annual cash compensation for Board services, as applicable, paid in quarterly installments in arrears:

In addition to the cash compensation described above, each member of the Board who served on the Audit Committee, Compensation Committee or Nominating and Corporate Governance Committee received additional cash compensation as follows, paid in quarterly installments in arrears:

The annual cash compensation to our directors is pro-rated for any partial year of service on our Board or as a committee chair or committee member.

Equity Awards

The Company seeks to maintain competitive executive compensation in order to attract the most qualified candidates. The Company's non-employee director compensation program includes equity awards granted to directors annually and upon appointment to the Board as follows:

Non-employee directors receive an annual equity award grant with an aggregate value of $275,000. Of this amount, 75% is in the form of non-statutory stock options and 25% of the value is in the form of restricted stock units ("RSUs"), in each case rounded down to the nearest whole share. The exercise price per share price for each option is equal to the fair market value of our common stock on the grant date. The options vest in equal monthly installments over the 12 months following the grant date, with immediate full vesting in the event of a change in control. The RSUs vest in full on the first anniversary of the first day of the month in which the RSUs were granted, with immediate full vesting in the event of a change in control.

Each newly appointed non-employee director receives an initial equity award grant with an aggregate value of $550,000, of which 75% of the value is in the form of non-statutory stock options and 25% of the value is in the form of RSUs, in each case rounded down to the nearest whole share. The exercise price per share for each option is equal to the fair market value of our common stock on the grant date. The options vest in equal monthly installments over the 36 months following the grant date, with immediate full vesting in the event of a change in control. The RSUs vest over a three-year period, with one-third of the aggregate number of shares subject to the RSU award vesting on each of the first, second and third anniversaries of the first day of the month in which the RSUs were granted, with immediate full vesting in the event of a change in control.

Other Compensation

We reimburse our non-employee directors for their reasonable out-of-pocket expenses incurred in attending Board and committee meetings. We also provide customary director and officer insurance for all directors.

2023 Director Compensation Table

The following table sets forth a summary of the compensation we paid to our non-employee directors in 2023:

As of December 31, 2023, our non-employee directors held the following unvested RSUs and outstanding options to purchase shares of our common stock:

PROPOSAL 2:

RATIFICATION OF APPOINTMENT OF

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

The Audit Committee of the Board has selected PwC as our independent registered public accounting firm to perform the audit of our financial statements for the year ending December 31, 2024, and has further directed that management submit this selection for ratification by our stockholders at the Annual Meeting. PwC has served as our independent registered public accounting firm since 2015. Representatives of PwC are expected to be present at the Annual Meeting. They will have an opportunity to make a statement if they so desire and will be available to respond to appropriate questions.

The Audit Committee believes that the continued retention of PwC is in the best interests of the Company and our stockholders. As provided in the Audit Committee charter, the Audit Committee is directly responsible for the appointment, retention, compensation and oversight of the independent registered public accounting firm retained to audit the Company’s financial statements. The Audit Committee annually reviews the independent registered public accounting firm’s independence, including reviewing all relationships between the independent registered public accounting firm and us and any disclosed relationships or services that may impact the performance, objectivity or independence of the independent registered public accounting firm.

In determining whether to reappoint PwC as the Company’s independent registered public accounting firm, the Audit Committee took into consideration a number of factors, including the length of time the firm has been engaged, the quality of the Audit Committee’s ongoing discussions with PwC, an assessment of the professional qualifications and past performance of PwC and the potential impact of changing independent registered public accounting firms. Through its experience with the Company, PwC has gained institutional knowledge and expertise regarding the Company’s operations, accounting policies and practices and internal control over financial reporting. The Audit Committee believes that appointing a new independent registered accounting firm would require a significant time commitment that could interfere with management’s focus on financial reporting and internal controls.

Neither our Bylaws nor other governing documents or laws require stockholder ratification of the selection of PwC as our independent registered public accounting firm. However, the Audit Committee is submitting the selection of PwC to the stockholders for ratification as a matter of good corporate practice. If the stockholders fail to ratify the selection, the Audit Committee will reconsider whether or not to retain PwC. Even if the selection is ratified, the Audit Committee in its discretion may direct the appointment of a different independent registered public accounting firm at any time if it determines that such a change would be in the best interests of the Company and our stockholders.

Vote Required

In order for Proposal 2 to pass, the number of votes cast “For” Proposal 2 must exceed the number of votes cast against Proposal 2. Abstentions and broker non-votes will not be counted either “For” or “Against” the proposal and will have no effect on the proposal. We do not expect to receive broker non-votes on this proposal because the ratification of the appointment of the independent registered public accounting firm is considered a "routine" matter for which banks, brokers or other nominees are generally empowered to vote any shares for which a beneficial owner does not provide voting instructions.

Independent Registered Public Accounting Firm’s Fees

The following table represents aggregate fees billed to the Company for the years ended December 31, 2023 and 2022, by PwC, our independent registered public accounting firm:

Audit Fees

Audit fees consist of aggregate fees billed or incurred by PwC for professional services rendered in connection with the integrated audit of the consolidated annual financial statements and internal control over financial reporting, the review of financial statements included in the Company's quarterly reports on Form 10-Q and the review of registration statements filed with the SEC.

All Other Fees

All other fees consist of license fees billed for an annual subscription to accounting literature and tools offered by PwC.

All audit fees and other fees described above were pre-approved by the Audit Committee in accordance with applicable SEC requirements.

Pre-Approval Policies and Procedures

The Audit Committee’s policy is to pre-approve all audit and permissible non-audit services rendered by PwC, our independent registered public accounting firm. The Audit Committee can pre-approve specified services in defined categories of audit services, audit-related services, tax services and all other services up to specified amounts, as part of the Audit Committee’s approval of the scope of the engagement of PwC or on an individual case-by-case basis before PwC is engaged to provide a service.

Recommendation of the Board

The Board unanimously recommends a vote “For” the ratification of the appointment of PwC as our independent registered public accounting firm for the year ending December 31, 2024.

AUDIT COMMITTEE REPORT

The Audit Committee of the Board is composed entirely of independent directors. The Board annually reviews the Nasdaq listing standards’ definition of independence for Audit Committee members (including the requirements of Rule 10A-3 promulgated under the Exchange Act) and has determined that each member of the Audit Committee meets that standard. George Migausky serves as an audit committee financial expert in accordance with applicable SEC regulations.

The Board is responsible for the Company’s corporate governance. The purpose of the Audit Committee is to assist the Board in fulfilling its oversight responsibilities relating to the Company’s financial accounting, internal controls, reporting and compliance. The Audit Committee is responsible for selecting and engaging the Company’s independent auditor and approving the audit and non-audit services to be provided by the independent auditor. The Audit Committee’s function is more fully described in its charter, which the Board has adopted. The Audit Committee reviews its charter on an annual basis and makes recommendations to the Board with respect to potential amendments.

The Audit Committee relies on the expertise and knowledge of management, the Company’s internal audit function and the Company’s independent registered public accounting firm, PwC, in carrying out its responsibilities. The Company’s management is responsible for preparing the Company’s financial statements and for the Company’s financial reporting process, including the Company’s internal control over financial reporting and disclosure controls and procedures. PwC is responsible for performing an independent audit of the Company’s financial statements and expressing an opinion on the conformity of those financial statements with accounting principles generally accepted in the United States and for auditing the effectiveness of the Company’s internal control over financial reporting based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

The Audit Committee has reviewed and discussed with the Company’s management and PwC the audited financial statements for the fiscal year ended December 31, 2023 that were included in the Annual Report, as well as the effectiveness of the Company’s internal control over financial reporting as described in the Annual Report. The Audit Committee also reviewed and discussed with the Company’s management and PwC the unaudited interim financial statements that appeared in the Company’s Quarterly Reports on Form 10-Q that were filed with the SEC in 2023. In addition, the Audit Committee discussed with PwC those matters required to be discussed by the applicable requirements of the Public Company Accounting Oversight Board (“PCAOB”) and the SEC, including the scope and results of PwC’s audits, the Company’s critical accounting policies and estimates, new accounting guidance and the critical audit matter identified during the audit. PwC provided the Audit Committee with the written disclosures and the letter required by applicable requirements of the PCAOB regarding PwC’s communications with the Audit Committee regarding PwC’s independence and the Audit Committee and PwC discussed PwC’s independence from the Company. The Audit Committee and PwC had full access to each other and met in periodic executive sessions without management present.

Based upon the review and discussions described above, the Audit Committee recommended to the Board that the audited financial statements be included in the Annual Report for filing with the SEC. The Audit Committee has reviewed the performance of PwC and selected PwC as the Company’s independent registered public accounting firm for the year ending December 31, 2024. The Audit Committee has also recommended to the Board that its appointment of PwC be submitted to the Company’s stockholders for ratification.

PROPOSAL 3:

ADVISORY VOTE ON EXECUTIVE COMPENSATION

In accordance with Section 14A of the Exchange Act, we are holding a stockholder advisory vote on the compensation of our named executive officers, or a “say-on-pay vote,” as described in the “Executive Compensation” section, the tabular disclosure regarding such compensation and the accompanying narrative disclosure set forth in this Proxy Statement. At the Annual Meeting, stockholders will be asked to approve the following resolution:

RESOLVED, that the stockholders of REGENXBIO Inc. (the “Company”) hereby approve, on a non-binding advisory basis, the compensation of the Company’s named executive officers, as disclosed in the Compensation Discussion and Analysis and compensation tables thereto pursuant to the compensation disclosure rules of the Securities and Exchange Commission.

The Compensation Committee oversees and administers our executive compensation program, including the evaluation and approval of compensation plans, policies and programs offered to our named executive officers. Our executive compensation program is designed to meet the following objectives:

Please see the “Executive Compensation” section of this Proxy Statement for a detailed discussion about our executive compensation program, including information about the 2023 compensation of our named executive officers.

While this vote is being conducted on an advisory basis, and is therefore not binding on us, the vote will be carefully considered by the Compensation Committee and the Board. Both the Compensation Committee and the Board value the opinions of our stockholders and, to the extent there is any meaningful vote against the compensation of our named executive officers as disclosed in this Proxy Statement, we will consider our stockholders’ concerns and evaluate what actions, if any, may be appropriate to address those concerns. The outcome of the vote, however, will not be construed as overruling any prior decision by the Company, the Compensation Committee or the Board. The current frequency of non-binding advisory votes on executive compensation is an annual vote.

Vote Required

In order for Proposal 3 to pass, the number of votes cast “For” Proposal 3 must exceed the number of votes cast “Against” Proposal 3. Abstentions and broker non-votes will not be counted either “For” or “Against” the proposal and will have no effect on the proposal.

Recommendation of the Board

The Board unanimously recommends a vote “For” thE approval, on an advisory basis, of the 2023 compensation of our Named Executive Officers.

INFORMATION ABOUT OUR EXECUTIVE OFFICERS

The names of the current executive officers of the Company and certain information about each of them are set forth below:

Kenneth T. Mills. For information regarding Mr. Mills, our President and CEO and a member of our Board, see “Proposal 1: Election of Directors.”

Vit Vasista, age 56, is currently our EVP, Chief Financial Officer and has been our Chief Financial Officer since August 2009. Prior to joining us, Mr. Vasista served as Principal at PRTM Management Consultants from October 2006 to July 2009, where he developed operational strategies for both private and public organizations, including the development of market entry strategies, innovative business models, and operational improvements. Mr. Vasista received an M.B.A. from The Wharton School at the University of Pennsylvania, an M.S. in Mechanical Engineering from Stanford University, and an S.B. in Mechanical Engineering from the Massachusetts Institute of Technology.

Curran Simpson, age 62, is currently our EVP, Chief Operating Officer and has been on our senior management team since August 2015. Prior to joining us, Mr. Simpson was the Regional Supply Chain Head for North America at GlaxoSmithKline plc (“GSK”), a pharmaceutical company, from December 2012 until August 2015. Mr. Simpson was the Senior Vice President, Operations at the Human Genome Sciences division of GSK (“HGS”) from July 2006 to December 2012, as well as the Vice President, Manufacturing Operations at HGS from January 2003 to June 2006. Prior to HGS, Mr. Simpson held various positions with Biogen, Inc., Covance Biotechnology Services Inc., Novo-Nordisk Biochem Inc., Genentech, Inc. and Genencor, Inc. Mr. Simpson received an M.S. in Surface and Colloid Science (Physical Chemistry) from Clarkson University and a B.S. in Chemistry/Chemical Engineering from Clarkson College of Technology.

Steve Pakola, M.D., age 55, is currently our EVP, Chief Medical Officer and has been our Chief Medical Officer since April 2019. Prior to joining us, Dr. Pakola served as Chief Medical Officer of Aerpio Pharmaceuticals, Inc. from October 2015 until April 2019. From April 2012 until October 2015, Dr. Pakola was the Chief Medical Officer of Amakem NV, a biopharmaceutical company. Prior to Amakem, from May 2000 until April 2012, Dr. Pakola was the Chief Medical Officer of ThromboGenics NV, a biopharmaceutical company, where he was the lead inventor and program lead for the Jetrea (ocriplasmin) program. Dr. Pakola received an M.D. and a B.A. in Biology, each from the University of Pennsylvania.

Olivier Danos, Ph.D., age 66, is currently our EVP, Chief Scientific Officer and has been our Chief Scientific Officer since March 2017. Prior to joining us, Dr. Danos was the Senior Vice President, Cell and Gene Therapy at Biogen Inc., a biotechnology company, from September 2014 until March 2017, where he led its gene therapy research and development activities. From September 2011 to September 2014, Dr. Danos was the Senior Vice President, Molecular Medicine, Synthetic Biology and Gene Regulation at Kadmon Pharmaceuticals. Prior to Kadmon, Dr. Danos served as the Director of the Gene Therapy Consortium of the University College of London and led a gene therapy research team at the Necker Hospital—Enfants Malades in Paris. He also served as the Chief Scientific Officer at Genethon and Senior Director of Research at Somatix Therapy Corporation, and held senior roles at the French National Centre for Scientific Research and the Pasteur Institute in Paris. Dr. Danos is the former President and founding member of the European Society of Gene and Cell Therapy. Dr. Danos received a Ph.D. in Biology from the Pasteur Institute and University of Paris Diderot and a Master in Science in Genetics and Molecular Biology at the University of Paris Orsay.

Patrick J. Christmas, age 53, is currently our EVP, Chief Legal Officer and has been on our senior management team since August 2016. Prior to joining us, Mr. Christmas served as Interim General Counsel at Tolero Pharmaceuticals, Inc. from April 2015 until August 2016. From May 2011 until November 2014, Mr. Christmas was the Vice President, General Counsel of Lumara Health, a specialty pharmaceutical company, until the company's acquisition. Prior to Lumara Health, Mr. Christmas was General Counsel at the Wellstat Companies, a group of biotechnology companies, from July 2007 until May 2011 and General Counsel at BioVeris Corporation, a publicly held diagnostics company, from April 2005 to July 2007, until the company's acquisition by F. Hoffman LaRoche Ltd.. Mr. Christmas began his career as an Associate at the law firm of Akin Gump Strauss Hauer & Feld LLP. Mr. Christmas received a J.D. from the University of Notre Dame and a B.A. in Economics from Boston College.

EXECUTIVE COMPENSATION

Compensation Discussion and Analysis

This Compensation Discussion and Analysis (“CD&A”) explains our compensation philosophy, policies and decisions for 2023 for the following executives, whom we refer to in this CD&A and in the related tables as our named executive officers (“NEOs”):

Executive Summary of Our 2023 Achievements

We are a leading clinical-stage biotechnology company seeking to improve lives through the curative potential of gene therapy. Our investigational gene therapies are designed to deliver functional genes to address genetic defects in cells, enabling the production of therapeutic proteins or antibodies that are intended to impact disease. Our investigational gene therapies use adeno-associated virus (“AAV”) vectors from our proprietary gene delivery platform, which we call our NAV Technology Platform. Our NAV Technology Platform consists of exclusive rights to a large portfolio of AAV vectors, including commonly used AAV8, and AAV9 vectors. We and our third-party NAV Technology Platform Licensees are applying the NAV Technology Platform to a number of investigational gene therapies and one FDA-approved product over a broad range of therapeutic areas and disease indications.

In 2023, we made significant progress toward our clinical development and business objectives, including the following achievements, which impacted executive compensation:

Compensation Philosophy and Objectives

The rapidly growing gene therapy industry has created a competitive recruitment and retention market for strong talent. It is our goal to ensure that we have the most skilled, innovative and resourceful executives on our leadership team. We foster an environment at REGENXBIO that will attract and retain top talent, and our executive compensation program is designed to support those objectives. Our program is structured around the following philosophy and objectives:

2021 CEO Compensation Cash Incentive Awards 5% All Other Compensation 1% Salary 7% Special Bonus 7% RSU Awards 21% Option Awards 59% 2021 Variable Performance-Based vs Guaranteed CEO Compensation Guaranteed Compensation (Salary and All Other Compensation) 8% Variable Performance-Based Compensation (Option Awards RSU Awards Special One Time Bonus and Cash Incentive Awards) 92% 2021 All Other NEO Compensation Cash Incentive Awards7% All Other Compensation Salary1% Salary 14% Special Bonus 10% RSU Awards 18% Option Awards 50% 2021 Variable Performance-Based vs Guaranteed All Other NEO Compensation Guaranteed Compensation (Salary and All Other Compensation) 15% Variable Performance Based Compensation (Option Awards RSU Awards Special One Time Bonus and Cash Incentive Awards) 85%

Oversight and Operation of our Executive Compensation Program

Our executive compensation program demonstrates a commitment to a robust process and strong corporate governance practices, as evidenced by the following:

Process of Determining Executive Compensation

Role of the Compensation Committee. Our Compensation Committee has been delegated the authority by the Board to make determinations regarding all elements of compensation for our executives. The Compensation Committee engages an independent compensation consultant to advise it on the competitiveness of the executive compensation program, including an annual peer group review and annual analysis of all elements of executive compensation for each executive. Compensation packages for each executive are typically finalized and approved at the first Compensation Committee meeting each year.

Role of Management. In making executive compensation decisions, our Compensation Committee may solicit input from management as appropriate with respect to individual and Company performance and results. The Compensation Committee receives recommendations and evaluations with respect to the compensation and performance of our executives from our President and CEO (except for his own compensation and performance). The EVP, Chief People Officer works with our compensation consultant to provide any external market data it requires. The Compensation Committee considered assessments from management when making 2023 compensation decisions.

Role of the Compensation Consultant. Our Compensation Committee is authorized to select and retain its own independent compensation consultant. The Compensation Committee has retained Willis Towers Watson in this role since April 2019. The compensation consultant has annually conducted a comprehensive assessment of our executive compensation program and pay levels, advised the Compensation Committee on evolving best practices in executive compensation and provided benchmarking data and recommendations. The Compensation Committee conducted an evaluation of Willis Towers Watson and concluded that the engagement did not raise any conflict of interest.

Peer Group Data. Our Compensation Committee reviews our peer group annually to ensure it remains relevant and current. Our Compensation Committee, upon advice received from its independent compensation consultant, selected the 14 companies that comprised our peer group for determining 2023 compensation through a screening process that considered publicly traded biopharmaceutical companies similar to us in headcount and market capitalization.

Our 2023 peer group companies were as follows:

Survey Data. In addition to using peer group data, the Compensation Committee references survey data for comparable companies from the Radford Global Life Sciences Survey to inform compensation decisions.

Elements of Compensation

Compensation packages for our NEOs in 2023 included the following elements:

The elements of our 2023 executive compensation program and compensation decisions for NEOs are described in further detail below.

Base Salary

Our Compensation Committee reviews and sets base salaries for NEOs, other than the President and CEO, on an annual basis in January of each year. Our Board determines the base salary for our President and CEO based on the recommendation of the Compensation Committee.

Our Compensation Committee and Board seek to establish and maintain base salaries for each position and level of responsibility that are competitive with those of executives at our peer group companies. In determining the base salary for each executive, the Compensation Committee takes many factors into account, including but not limited to:

Our NEOs were given merit increases to their base salaries in 2023 as a result of their respective performances in 2022. In consideration of the factors described above, the base salaries for our NEOs were adjusted as follows in 2023:

Annual Short-Term Cash Incentive

We have an annual cash incentive program for all employees, which is intended to align corporate, departmental, and individual goals throughout the Company and to provide an incentive that further ties compensation to achievement of those goals. In establishing targets for the cash incentive awards for our NEOs, the Compensation Committee (and the Board, in the case of our President and CEO) considers cash incentive awards paid to executives in similar positions at our peer group companies.

For 2023, target cash incentive award percentages remained the same from the prior year, as reflected in the table below:

For 2023, our Compensation Committee determined that the cash incentive awards for our NEOs, except for our President and CEO, Mr. Mills, would be determined based on corporate and individual objectives. Given Mr. Mills’ more substantial influence on the overall performance of the Company, the Compensation Committee believed it was appropriate and in the best interests of the Company to have Mr. Mills’ cash incentive award be based solely upon the achievement of corporate objectives, and the independent Board members concurred. The Compensation Committee believes that including the achievement of individual goals as a component of our cash incentive award payouts is important to motivate our NEOs other than Mr. Mills, as we continue to progress toward the commercial phase of our Company. For 2023, weightings allocated to corporate and individual objectives were as follows:

The Company’s annual cash incentive program, which is approved by the Compensation Committee and applicable to all employees, utilizes both a corporate performance multiplier and an individual performance multiplier. The corporate performance multiplier is based on the degree to which the Company’s objectives have been achieved during the relevant year; this multiplier is determined by the Compensation Committee and may range from 0 to 200% of target, provided that, if it is determined to be less than 50% of target, there will be no payout for the portion of our annual incentive program that is attributable to corporate performance. The individual performance modifier is based on the degree to which each employee’s individual objectives have been achieved during the relevant year; this multiplier is approved by the Compensation Committee for each of our NEOs and may range from 0 to 200% of target.

Corporate Objectives

Near the beginning of each year, our management recommends annual corporate objectives to our Compensation Committee and Board for approval. These objectives serve as the basis for determining our performance against key strategic and operating parameters for the year.

The Compensation Committee and the Board approved the corporate objectives and weightings for 2023 as reflected in the table below. At the time of approval, the Compensation Committee believed that these objectives were challenging, but attainable, and that attainment was uncertain.

Individual Objectives

Our President and CEO, in consultation with our other NEOs, identified individual objectives for each of our other NEOs near the beginning of 2023 that were specific to each of their respective areas of responsibility and supported meeting our corporate objectives. These individual objectives were then recommended to and approved by our Compensation Committee. At the time of approval, the Compensation Committee believed these objectives were challenging, but attainable, and that attainment was uncertain.

Our Compensation Committee, with input from our President and CEO, made a determination following the end of the year as to the level of achievement of the respective individual objectives by each of our NEOs, other than our President and CEO.

Determining Payouts of Annual Cash Incentives

With respect to our 2023 corporate objectives, our Board and Compensation Committee determined that we achieved a payout percentage of 75% of target based on our corporate performance. When assessing the payouts, the Board and Compensation Committee took into account our overall financial condition at the time and our performance relative to our annual corporate objectives. The Compensation Committee determined that all NEOs were instrumental in meeting our corporate objectives.

The determination of the Board and Compensation Committee regarding our performance relative to each corporate objective is shown in the following table:

Based on the Company’s level of performance in 2023 relative to our corporate goals, and based on the level of performance of each NEO other than our President and CEO in 2023 relative to individual goals, our NEOs earned the cash incentive awards shown in the following table for 2023:

Long-term Equity Incentives

Equity awards are crucial to a competitive compensation program for executives because they act as a powerful retention incentive. Equity ownership in our Company by our NEOs also aligns the interests of our NEOs with those of our stockholders and rewards our NEOs for their contributions to our long-term success.

In determining the equity incentive awards for our NEOs in 2023, our Board, with respect to our President and CEO, and our Compensation Committee, with respect to our other NEOs, considered the roles and performance of each NEO as well as the benchmarking data and recommendations of the Compensation Committee’s independent compensation consultant, which included information regarding equity compensation received by executives at peer group companies, as well as broader survey data. In 2023, our NEOs were given the option to receive their annual equity awards allocated as follows, with the total estimated grant date fair value of the equity awards being equal in each case: (i) 50% stock options and 50% RSUs, (ii) 75% stock options and 25% RSUs, or (iii) 100% stock options. We believe this optionality allows our NEOs to maximize the potential value of their equity awards based on individual circumstances and maintains alignment of the interests of our NEOs with those of our stockholders. Based on the considerations above and elections by each officer, our NEOs received the following stock option and RSU awards in 2023:

Shares of our common stock underlying the options in the above table will vest over a four-year period, with 25% of the shares vesting after 12 months from the date of grant and the balance vesting in equal monthly installments over the 36 months thereafter, provided that the optionee provides continuous service to the Company. Shares of our common stock underlying the RSUs in the above table will vest over a four-year period, with 25% of the shares vesting on each of the first, second, third and fourth anniversaries of the first day of the month in which the RSU was granted, provided that the recipient provides continuous service to the Company.

The Board, with respect to our President and CEO, and the Compensation Committee, with respect to our other NEOs, has also granted stock options and RSUs from time to time outside of our annual equity incentive awards and one-time awards upon joining the Company, in recognition of an NEO’s expanded role or continuing contributions to the Company’s performance. No such grants were made in 2023.

Health, Welfare and Retirement Benefits

Our NEOs are eligible to participate in our health and welfare plans to the same extent as all full-time employees are eligible, including reimbursement of certain medical expenses of the NEO or employee and, if applicable, his or her eligible dependents. We pay a portion of the premium cost for our group health plan for all participants, including our NEOs. Other health and welfare benefits include medical, dental, vision and life insurance, flexible spending accounts and short- and long-term disability.

We have established a 401(k) tax-deferred savings plan, which permits all participants, including our NEOs, to make contributions by salary deduction pursuant to Section 401(k) of the Internal Revenue Code (the “Code”). We are responsible for administrative costs of the 401(k) plan. We may, at our discretion, make matching contributions to the 401(k) plan. We do not generally provide our NEOs with any other perquisites or personal benefits. In 2023, the Compensation Committee approved the payment of corporate housing costs and a related tax gross-up for Dr. Danos in order to maximize the amount of time that Dr. Danos can devote to Company business by minimizing his commuting time to our headquarters from his personal residence in another state. The Compensation Committee believes such benefits to the Company significantly outweighed the incremental expense to the Company.

Our employee stock purchase plan permits participants, including our NEOs, to purchase our common stock at a discount on a tax-qualified basis through payroll deductions. The employee stock purchase plan is designed to qualify as an “employee stock purchase plan” under Section 423 of the Code. The purpose of the employee stock purchase plan is to encourage our employees, including our NEOs, to become our stockholders and better align their interests with those of our other stockholders.

Severance and Change in Control Benefits

We have entered into employment agreements with each of our NEOs which, among other things, provide for certain severance and change in control payments under certain circumstances. We believe these potential benefits discourage turnover and allow our NEOs to respond to the possibility of a change in control without being influenced by the potential effects of a change in control on their job security. These potential benefits and our employment agreements with our NEOs are described in further detail under “—Employment Agreements and Potential Payments Upon Termination or Change in Control.”

Anti-Hedging and Pledging Policy

As part of our policy against insider trading, our directors, officers, employees and certain other individuals are prohibited from purchasing financial instruments that are designed to hedge or offset any decrease in the market value of the Company’s securities. Additionally, such individuals are prohibited from engaging in transactions involving options on the Company’s securities, such as puts, calls and other derivative securities, except when receiving or exercising options granted by the Company. “Short sales” of the Company’s securities (sales of securities not already owned) are also prohibited. Furthermore, pledging of any Company securities is not permitted without the prior approval of the Company.

Clawback Policy

The Company has adopted a comprehensive Compensation Clawback Policy, which provides for the recoupment of any executive officer compensation that is granted, earned or vested based wholly or in part based on stock price, total shareholder return, and/or the attainment of (i) any financial reporting measure(s) that are determined and presented in accordance with the accounting principles used in preparing the Company’s financial statements and/or (ii) any other measures that are derived in whole or in part from such measures (“Incentive-Based Compensation”) in the event of an accounting restatement due to our material noncompliance with any financial reporting requirement under the securities laws, including any required accounting restatement to correct an error in previously issued financial statements that is material to the previously issued financial statements, or that corrects an error that is not material to previously issued financial statements but would result in a material misstatement if the error were corrected in the current period or left uncorrected in the current period (“Accounting Restatement”). In the event of an Accounting Restatement the executive officer must return the Incentive-Based Compensation to the extent it would not have been paid or awarded had the Accounting Restatement not occurred. This applies during a lookback period of the three completed fiscal years preceding the date we are required to prepare an Accounting Restatement, and the amounts to be reclaimed are as determined by the Board in its sole discretion. All executive officers are required to agree to this policy in writing.

Compensation Committee Report

The Compensation Committee has reviewed and discussed the foregoing Compensation Discussion and Analysis with management. Based on this review and discussion, the Compensation Committee recommended to the Board that the Compensation Discussion and Analysis be included in this Proxy Statement and incorporated by reference into the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023.

The Compensation Committee

Daniel Tassé, Chair

Alexandra Glucksmann, Ph.D.

A.N. “Jerry” Karabelas, Ph.D.

Summary Compensation Table

The following table provides information concerning the compensation earned by our NEOs during the years ended December 31, 2023, 2022 and 2021:

2023 Grants of Plan-Based Awards

The following table sets forth certain information regarding grants of plan-based awards to our NEOs during the year ended December 31, 2023. No other plan-based awards were granted to any of our current or former NEOs during 2023.

Outstanding Equity Awards at 2023 Fiscal Year-End

The following table sets forth information regarding outstanding and unexercised options and unvested RSUs held by each of our NEOs as of December 31, 2023. The number of shares subject to each award and, where applicable, the exercise price per share, reflects all changes as a result of our capitalization adjustments. The vesting schedule applicable to each outstanding award is described in the footnotes to the table below.