UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

(Rule 14a-101)

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934

(Amendment No.    )

Filed by the Registrant  x☒                             Filed by a party other than the Registrant  ¨☐

Check the appropriate box:

REGENXBIO Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

REGENXBIO Inc.

9712 Medical Center Drive,9600 Blackwell Road, Suite 100210

Rockville, MD 20850

NOTICE OF ANNUAL MEETING OF STOCKHOLDERS

To Be Held On June 1, 2016

Dear Stockholder:

You are cordially invited to attend the Annual Meeting of Stockholders (the Annual Meeting)“Annual Meeting”) of REGENXBIO Inc., a Delaware corporation (the Company)“Company”). The Annual Meeting will be held on June 1, 2016,May 25, 2018, at 9:00 a.m. local time at the Company’s offices located at 97129714 Medical Center Drive, Suite 100, Rockville, Maryland 20850 for the following purposes:

The record date for the Annual Meeting is April 7, 2016. Only stockholders of record at the close of business on that date mayMarch 26, 2018 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 examinationinspection at ourthe Company’s offices in Rockville, Maryland during normal business hours for a period of ten10 days prior to the Annual Meeting.

YOUR VOTE IS IMPORTANT!

Your vote is important. Please voteWhether or not you plan to attend the Annual Meeting in person, please submit your proxy by usingtelephone or over the internet, or by telephone or, if you received a paper copy of thecompleting, signing, dating and returning your proxy card by mail, by signing and returningor voting instruction form so that your shares will be represented at the enclosed proxy card.Annual Meeting. Instructions for your voting options are described onin the Company’s proxy statement for the Annual Meeting, Notice of Internet Availability of Proxy Materials or proxy card.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR THE ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON MAY 25, 2018:

ImportantThe Company’s Notice Regarding the Availability of Proxy Materials for the StockholdersAnnual Meeting, to be held on June 1, 2016. The Proxy Statement and Annual Report onForm 10-K for the fiscal year ended December 31, 2017 are available atwww.proxyvote.com.www.proxyvote.com.

Your Board of Directors unanimously recommends you vote the proxy card “FOR” the Company’s two director nominees, Allan M. Fox and Camille Samuels and “FOR” Proposal 2.

This Proxy Statement is first being mailed to the stockholders of the Board of Directors,

Kenneth T. Mills

President and Chief Executive Officer

Rockville, Maryland

April 18, 2016

This notice of Annual Meeting and accompanying proxy statement are being distributed or made available to stockholdersCompany on or about April 18, 2016.12, 2018.

TABLE OF CONTENTS

i

REGENXBIO Inc.

9712 Medical Center Drive,9600 Blackwell Road, Suite 100210

Rockville, MD 20850

PROXY STATEMENT

FOR THE 2016 ANNUAL MEETING OF STOCKHOLDERS

June 1, 2016

This proxy statement and proxy card areProxy Statement is furnished in connection with the solicitation of proxies to be voted at the 20162018 Annual Meeting of Stockholders (the Annual Meeting)“Annual Meeting”) of REGENXBIO Inc. (sometimes referred to as we, the Company or REGENXBIO), which will be held on June 1, 2016,May 25, 2018, at 9:00 a.m. local time at the Company’s offices located at 97129714 Medical Center Drive, Suite 100, 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 statementProxy Statement and our Annual Report onForm 10-K for the fiscal year ended December 31, 2017 (the “Annual Report”) available to stockholders at www.proxyvote.com. On or about April 18, 2016,12, 2018, we will begin mailing to certain of our stockholders a noticeNotice of Internet Availability of Proxy Materials (the Notice)“Notice”) containing instructions on how to access and review this proxy statementProxy Statement and ourthe Annual Report on Form 10-K at that website.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.

QUESTIONS AND ANSWERS ABOUT THISTHE PROXY MATERIALMATERIALS AND VOTING

Why am I receiving this proxy statementProxy Statement and a related proxy card?

You have received these proxy materials because you owned shares of REGENXBIO common stock as of April 7, 2016,March 26, 2018, the record date for the Annual Meeting (the “Record Date”), and our Board of Directors (the “Board”) is soliciting your proxy to vote at the Annual Meeting. This proxy statementProxy Statement describes issuesmatters on which we would like you to vote at the Annual Meeting. It also gives you information on these issuesMeeting so that you can make an informed decision.

Why did I receive a Notice of Internet Availability of Proxy Materials in the mail instead of a printed set of proxy materials?

Pursuant to rules adopted by the Securities and Exchange Commission (SEC)(the “SEC”), we are permitted to furnish our proxy materials over the internet to our stockholders by delivering athe Notice in the mail. As a result, only stockholders who specifically request a printed copy of the proxy statementProxy Statement will receive one. Instead, the Notice instructs stockholders on how to access and review the proxy statementProxy Statement and Annual Report on Form 10-K over the internet at www.proxyvote.com. The Notice also instructs stockholders on how they may submit their proxy overvia telephone or the internet or telephone.internet. If a stockholder who received a Notice would like to receive a printed copy of our proxy materials, such stockholder should follow the instructions for requesting these materials contained in the Notice.

How may I vote at the Annual Meeting?

You are invited to attend the Annual Meeting to vote on the proposals described in this proxy statement.Proxy Statement. However, you do not need to attend the meetingAnnual Meeting to vote your shares. Instead, you may simply follow the instructions below to submit your proxy via telephone or on the internet. If you received a printed set of materials, you may also vote by mail by completing, signing, dating and returning the proxy card.

When you vote, regardless of the method used, you appoint Kenneth T. Mills, our President and Sara Garon BerlChief Executive Officer, and Patrick J. Christmas, our General Counsel, as your representatives (or proxyholders) atfor the Annual Meeting. They will vote your shares at the Annual Meeting as you have instructed them or, if an issuea matter that is not on the proxy card comes up for vote, in accordance with their best judgment. This way, your shares will be voted whether or not you attend the Annual Meeting.

Who is entitled to vote at the Annual Meeting?

Only stockholders of record at the close of business on April 7, 2016, the record date for the Annual Meeting,Record Date will be entitled to vote at the Annual Meeting. On the record date,Record Date, there were 26,338,32931,870,555 shares of the Company’sour common stock outstanding. All of these outstanding shares are entitled to vote at the Annual Meeting (one vote per share of common stock) in connection with the matters set forth in this proxy statement.Proxy Statement.

In accordance with Delaware law, aA list of stockholders entitled to vote at the meeting will be available at the place of the Annual Meeting on June 1, 2016 and will be accessible for ten10 days prior to the meetingAnnual Meeting at our principal place of business, 9712 Medical Center Drive,9600 Blackwell Road, Suite 100,210, Rockville, MDMaryland 20850, between the hoursduring ordinary business hours.

What is a stockholder of 9:00 a.m.record and 5:00 p.m. local time.

How dohow can I vote?vote if I am a stockholder of record?

If, on April 7, 2016,the Record Date, your shares of common stock were registered directly in your name with our transfer agent, Computershare Trust Company, N.A., then you are a stockholder of record. Stockholders of record may vote by usingvia the internet, by telephone or mail (if you received a proxy card by mail) by mail as described below. Stockholders also may attend the meeting and vote in person. If you hold shares through a bank, broker or other nominee, please refer to your proxy card, Notice or other information forwarded by your bank, broker or other nominee to see which voting options are available to you.

The method you use to vote will not limit your right to vote at the Annual Meeting if you decide to attend in person. Written ballots will be passed out to anyone who wants to vote at the Annual Meeting. In all cases, your shares will be voted according to your instructions.

What is a beneficial owner of shares and how can I vote if I am a beneficial owner?

If, on the Record Date, your shares of common stock were not held in your name, but rather were held through a bank, broker or other nominee, then you are the beneficial owner of shares held in “street name,” and you will need to submit voting instructions to the institution that holds your shares. If you do not give instructions to your broker, your broker can vote your shares only with respect to “discretionary” items, but not with respect to“non-discretionary” items. Discretionary items are proposals considered routine under the rules on which your broker may vote shares held in street name without your voting instructions. Onnon-discretionary items for which you do not give your broker instructions, the shares will not be voted, which is referred to as a “brokernon-vote.” Banks, brokers and other nominees are not permitted to vote your shares for the election of directors if the shares are held in street name and they do not receive instructions from you. Accordingly, if you hold your shares in “streetstreet name,” your shares will not be voted on Proposal 1 relating to the election of directors

unless you must obtainprovide voting instructions to the record holder. Banks, brokers and other nominees will have discretion to vote uninstructed shares on Proposal 2 relating to the ratification of the selection of our independent registered public accountants.

As a proxy, executed in your favor, frombeneficial owner, you are invited to attend the holderAnnual Meeting. If you are a beneficial owner and not the stockholder of record, to be able toyou may not vote your shares in person at the Annual Meeting.Meeting unless you request and obtain a valid proxy from your bank, broker or other nominee.

Can I change my vote after submitting my proxy?

Yes. You can revoke your proxy at any time before the final vote at the Annual Meeting. If you are the record holder of your shares, you may revoke your proxy in any one of three ways:

If you are a beneficial owner ofhold your shares in street name, you must contact the bank, broker or other nominee holding your shares and follow their instructions for changing your vote.

How many votes do you need to holdWhat is the Annual Meeting?quorum requirement?

A quorum of stockholders is necessary to conduct business at the Annual Meeting. Pursuant to our amendedAmended and restated bylaws,Restated Bylaws (the “Bylaws”), a quorum will be present if a majority of the voting power of outstanding shares of the Company entitled to vote generally in the election of directors is represented in person or by proxy at the Annual Meeting. On the record date,Record Date, there were 26,338,32931,870,555 shares of common stock outstanding and entitled to vote. Thus, 13,169,16515,935,278 shares must be represented by stockholders present at the Annual Meeting or represented by proxy to have a quorum.

Your shares will be counted towards the quorum only if you submit a valid proxy (or one is submitted on your behalf by your bank, broker bank or other nominee) or if you attend the Annual Meeting and vote in person. Abstentions and brokernon-votes will be counted for the purpose of determining whether a quorum is present for the transaction of business. If a quorum is not present, the chairman of the meeting or the holders of a majority of the votes present at the Annual Meeting may adjourn the Annual Meeting to another date.

What proposals will be voted on at the Annual Meeting?Meeting and what vote is required to approve each proposal?

The following table provides a description of the proposals that will be voted on at the Annual Meeting:

Plurality means that the nominees for director receiving the greatest number of votes will be elected. Withheld votes, abstentions and “broker non-votes”brokernon-votes will have no effect on the election of a nominee.

Majority Votes Castmeans that a proposal that receives an affirmative majority of the votes cast will be approved. Abstentions and brokernon-votes will not be counted “FOR”“For” or “AGAINST”“Against” this proposal and will have no effect on this proposal.

Broker Discretionary Voting occurs when a broker does not receive voting instructions from the beneficial owner and votes those shares in its discretionVotes on anyeach proposal on which it is permitted to vote.

How are votes counted?

Votes will be countedtabulated by the inspector of elections appointed for the meeting, who will separately count “For” and (with respect to proposals other than the election of directors) “Against” votes, abstentions and brokernon-votes. Abstentions will be counted towards the vote total for each proposal, and will have the same effect as “Against” votes. Broker non-votes, as described in the next paragraph, have no effect and will not be counted towards the vote total for Proposals 1 and 2.

If your shares are held by your broker as your nominee (that is, in “street name”), you will need to obtain a proxy form from the institution that holds your shares and follow the instructions included on that form regarding how to instruct your broker to vote your shares. If you do not give instructions to your broker, your broker can vote your shares with respect to “discretionary” items, but not with respect to “non-discretionary” items. Discretionary items are proposals considered routine under the rules on which your broker may vote shares held in street name without your voting instructions. Onnon-discretionary items for which you do not give your broker instructions, the shares will be treated as brokernon-votes. Under current broker voting rules, any election of a member of the Board of Directors, whether contested or uncontested, is considered“non-discretionary” and

therefore brokers are not permitted to vote your shares held in street name for the election of directors in the absence of instructions from you. Proposal 1 is“non-discretionary” and therefore if you hold your shares through a broker, bank or other agent, your shares will not be voted on Proposal 1 unless you provide voting instructions to the record holder.meeting.

Could other matters be decided at the Annual Meeting?

REGENXBIOThe Company does not know of any other matters that may be presented for action at the Annual Meeting. Should any other business come before the Annual Meeting, the personsindividuals named as proxies on the proxy card will have discretionary authority to vote the shares represented by proxies in accordance with their best judgment. If you hold shares through a bank, broker bank or other nominee, the individuals named as described above, theyproxies on the proxy card will not be able to vote your shares on any other business that comes before the Annual Meeting unless theysuch individuals receive instructions from you with respect to such other business.

What happens if a director nominee is unable to stand for election?

If a nominee is unable to stand for election, ourthe Board of Directors may either:

If ourthe Board of Directors designates a substitute nominee, shares represented by proxies voted for the nominee who is unable to stand for election will be voted for the substitute nominee.

What happens if I sign and returnsubmit my proxy card but do not provide voting instructions?

If you submit a proxy via telephone or the internet or return a signed and dated proxy card without marking any voting selections,indicating instructions with respect to specific proposals, your shares will be voted:voted as follows:

What do I need to show to attend the Annual Meeting in person?

You will need proof of your share ownership (such as a recent brokerage statement or letter from your broker showing that you owned shares of our common stock as of April 7, 2016)the Record Date and a form of photo identification.identification, such as a valid driver’s license. If you do not have proof of ownership and valid photo identification, you may not be admitted to the Annual Meeting. If you are a stockholder of record, your ownership as of the Record Date will be verified prior to admittance into the meeting. If you are not a stockholder of record but hold shares in street name, you must provide proof of beneficial ownership as of the Record Date, such as an account statement or similar evidence of ownership.

All bags, briefcases and packages will be held at registration and will not be allowed in the meeting.Annual Meeting. We will not permit the use of cameras (including cell phones and other devices with photographic capabilities) andor other recording devices in the meeting room.

Who is paying for this proxy solicitation?

The accompanying proxy is being solicited by the Board of Directors of the Company.Board. In addition to this solicitation, directors and employees of the Company may solicit proxies in person, by telephone, or by other means of communication. Directors and employees will not be paid any additional compensation for soliciting

proxies. In addition, the Company may also retain one or more third parties to aid in the solicitation of brokers, banks and institutional and other stockholders. We will pay for the entire cost of soliciting proxies. We may reimburse brokerage firms, banks and other agents for the cost of forwarding proxy materials to beneficial owners.

What happens if the Annual Meeting is postponed or adjourned?

Unless the polls have closed or you have revoked your proxy, your proxy will still be in effect and may be voted once the Annual Meeting is reconvened. However, you will still be able to change or revoke your proxy with respect to any proposal until the polls have closed for voting on such proposal.

How can I find out the results of the voting at the Annual Meeting?

Preliminary voting results are expected to be announced at the Annual Meeting. FinalWe expect to report final voting results will be reported onin a Current Report onForm 8-K filed with the SEC no later than the fourth business day after the Annual Meeting, or June 7, 2016.Meeting.

How can I find REGENXBIO’sthe Company’s proxy materials and Annual Report on the Internet?internet?

This proxy statementProxy Statement and the Annual Report on Form 10-K for the year ended December 31, 2015 are available at our corporate website at www.regenxbio.com. You also can obtain copies without charge at the SEC’s website at www.sec.gov. Additionally, in accordance with SEC rules, youwww.sec.gov and may access these materials at www.proxyvote.com, which does not have “cookies” that identify visitors to the site.www.proxyvote.com.

How do I obtain a separate set of REGENXBIO’sthe Company’s proxy materials if I share an address with other stockholders?

In some cases, stockholders holding their shares in a brokerage or bank account who share the same surname and address receive only one copy of the Notice. This practice, called “housekeeping,“householding,” is designed to reduce duplicate mailings and save printing and postage costs as well as natural resources. If you would like to have a separate copy of the Notice, or ourthe Annual Report on Form 10-K and/or proxy statementthis Proxy Statement mailed to you or to receive separate copies of future mailings, please submit your request to the address or phone number that appears on your Notice or proxy card. We will deliver such additional copies promptly upon receipt of such request.

In other cases, stockholders receiving multiple copies of proxy materials at the same address may wish to receive only one.one copy. If you would like to receive only one copy, if you now receive more than one, please submit your request to the address or phone number that appears on your Notice or proxy card.

Can I receive future proxy materials and annual reports electronically?

Yes. This proxy statementProxy Statement and the Annual Report on Form 10-K for the year ended December 31, 2015 are available on our investor relations website located at http://ir.regenxbio.com. Instead of receiving paper copies in the mail, stockholders can elect to receive an emaile-mail that provides a link to our future annual reports and proxy materials on the internet. Opting to receive your proxy materials electronically will save us the cost of producing and mailing documents to your home or business, will reduce the environmental impact of our annual meetings of stockholders and will give you an automatic link to the proxy voting site.

May I propose actions for consideration at next year’s annual meeting of stockholders or nominate individuals to serve as directors?

Yes. The following requirements apply to stockholder proposals, including director nominations, for the 2017our 2019 annual meeting of stockholders.stockholders:

Requirements for Stockholder Proposals to beBe Considered for Inclusion in REGENXBIO’sthe Company’s Proxy Materials:Materials

Stockholders interested in submitting a proposal (other than the nomination of directors) for inclusion in the proxy materials to be distributed by us for the 2017our 2019 annual meeting of stockholders may do so by following the procedures prescribed inRule 14a-8 of promulgated under the Securities Exchange Act of 1934, as amended (the Exchange Act)“Exchange Act”). To be eligible for inclusion in REGENXBIO’sthe Company’s proxy materials, stockholder proposals must be received at our principal executive offices no later than the close of business on December 19, 201613, 2018, which is the 120^th120th day prior to the first anniversary of the date that we released this proxy statementProxy Statement to our stockholders for the Annual Meeting. To be included in our proxy materials, your proposal also must comply with the Company’s amendedour Bylaws and restated bylaws and Rule 14a-8 promulgated under the Exchange Act regarding the inclusion of stockholder proposals in company-sponsored proxy materials. If we change the date of the 2017our 2019 annual meeting of stockholders by more than 30 days from the anniversary of this year’s Annual Meeting, stockholder proposals must be received a reasonable time before we begin to print and mail our proxy materials for the 2017our 2019 annual meeting of stockholders. ProposalsSuch proposals should be sent to REGENXBIO Inc., 9712 Medical Center Drive,9600 Blackwell Road, Suite 100,210, Rockville, MDMaryland 20850, Attn:Attention: Corporate Secretary.

Requirements for Stockholder Nomination of Director Candidates and Stockholder Proposals Not Intended for Inclusion in REGENXBIO’sthe Company’s Proxy Materials:Materials

Stockholders who wish to nominate persons for election to the Board of Directors at the 2017our 2019 annual meeting of stockholders or who wish to present a proposal at the 2017our 2019 annual meeting of stockholders, but who do not intend for such proposal to be included in REGENXBIO’sthe Company’s proxy materials for such meeting, must deliver written notice of the nomination or proposal to our Corporate Secretary at 9712 Medical Center Drive, Suite 100, Rockville, MD 20850our principal executive offices no earlier than February 1, 2017January 27, 2019, which is the 75th day prior to the first anniversary of the date we released this Proxy Statement to our stockholders for the Annual Meeting, and no later than March 3, 2017.February 26, 2019, which is the 45th day prior to the first anniversary of the date we released this Proxy Statement to our stockholders for the Annual Meeting. However, if we change the 2017date of our 2019 annual meeting of stockholders is held earlierby more than May 2, 2017 or later than July 1, 2017,30 days from the anniversary of this year’s Annual Meeting, such nominations and proposals must be received no later than the close of business on the later of (a) the 90^th90th day prior to the 2017our 2019 annual meeting of stockholders and (b) the 10th day following the day we first publicly announce the date of the 2017our 2019 annual meeting.meeting of stockholders. The stockholder’s written notice must include certain information concerning the stockholder and each nominee and proposal, as specified in our amendedBylaws. If the stockholder does not also satisfy the requirements ofRule 14a-4 promulgated under the Exchange Act, the persons named as proxies will be allowed to use their discretionary voting authority when and restated bylaws.if the matter is raised at the 2019 annual meeting of stockholders. Such nominations or proposals should be sent to REGENXBIO Inc., 9600 Blackwell Road, Suite 210, Rockville, Maryland 20850, Attention: Corporate Secretary.

Copy of Amended and Restated Bylaws:Bylaws

You may request a copy of the Company’s amended and restated bylawsour Bylaws to be delivered to you at no charge by writing to REGENXBIO’sthe Company’s Corporate Secretary at 9712 Medical Center Drive, Suite 100, Rockville, MD 20850.

Whom should I call if I have any questions?

If you have any questions, would like additional REGENXBIO proxy materials or proxy cards, or need assistance in voting your shares, please contact Investor Relations, REGENXBIO Inc., 9712 Medical Center Drive,9600 Blackwell Road, Suite 100,210, Rockville, MDMaryland 20850, or by telephone at (240) 552-8181.

Important Notice Regarding the AvailabilityAttention: Corporate Secretary. In addition, we have filed a copy of Proxy Materials

for the Meetingour Bylaws as Exhibit 3.2 to be Held on Wednesday, June 1, 2016

This proxy statement and our AnnualCurrent Report on Form 10-K are available on-line8-K filed on September 22, 2015, which may be accessed without charge on our website atwww.proxyvote.com. www.regenxbio.com and the SEC’s website at www.sec.gov.

PROPOSAL 1:

PROPOSAL 1

ELECTION OF ALLAN M. FOX AND CAMILLE SAMUELS AS CLASS I DIRECTORS

Under our amended and restated bylaws, ourBylaws, the Board of Directors is divided into three classes of roughly equal size. The members of each class are elected to serve a 3-yearthree-year term with the term of office of each of the three classes ending in successive years. Pursuant to our amended and restated bylaws,Bylaws, the Board of Directors has fixed the current number of directors at eight, but the number of directors will be seven following the expiration of Edgar G. Engleman,eight. Luke M. Beshar, Kenneth T. Mills and David C. Stump, M.D.’s term at the Annual Meeting. Edgar G. Engleman, M.D., Allan M. Fox and Camille Samuels are the three Class IIII directors whose terms expire at this Annual Meeting. On March 1, 2016,The Board has nominated Messrs. Beshar and Mills and Dr. Engleman informedStump (collectively, the Board of Directors that he would not stand for re-election at the Annual Meeting. Mr. Fox“nominees” and Ms. Samuels have been nominated for election by our Board of Directorseach, a “nominee”) to serve until the 20192021 annual meeting of stockholders or until their successors are elected, (oror until their earlier death, resignation or removal). It is our policy to encourage nominees for director to attend the Annual Meeting.

Directors are elected by a plurality of the votes cast at the Annual Meeting. The two 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.removal.

Shares represented by signed proxy cards will be voted on Proposal 1 “FOR”“For” the election of Mr. FoxMessrs. Beshar and Ms. SamuelsMills and Dr. Stump to the Board of Directors at the Annual Meeting, unless otherwise marked on the card. If any REGENXBIO director nomineeof 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 ourthe current Board, of Directors, unless otherwise marked on the card. Mr. FoxMessrs. Beshar and Ms. Samuels, REGENXBIO’s two director nominees,Mills and Dr. Stump have each agreed to serve as a director if elected. We have no reason to believe that eitherany of the REGENXBIO nominees will be unable to serve if elected.

Nominees for Election as Class I Directors at the Annual Meeting

This year’s nominees for election to the Board of Directors as our Class I directors to serve for a term of three years expiring at the 2019 annual meeting of stockholders, or until their successors have been duly elected and qualified or until their earlier death, resignation or removal, are provided below. The age of each director as of April 18, 2016 is set forth below.

The following is additionalCertain information about each of the nominees as of the date of this proxy statement,is furnished below, including their business experience, public company director positions held currently or at any time during the last five years involvement in certain legal or administrative proceedings, if applicable, and the experiences,experience, qualifications, attributes or skills that caused the Nominating and Corporate Governance Committee and ourthe Board of Directors to determine that the nominees should continue to serve as one of our directors.

AllanLuke M. FoxBesharhas been a Director since February 2009.April 2015. Mr. FoxBeshar is the founding partnera former Chief Financial Officer of FoxKiser, a nationally recognized 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. He has participated in the formation and development of numerous ventures in thevarious public and private sectors. Before forming FoxKiser,companies and has more than 30 years of general and financial management experience. Mr. Fox co-ledBeshar served as the establishmentExecutive Vice President and Chief Financial Officer of NPS Pharmaceuticals, Inc. from November 2007 to February 2015 and as Executive Vice President and Chief Financial Officer of Cambrex Corporation, a life sciences company, from December 2002 to November 2007. Mr. Beshar began his career with Arthur Andersen & Co., an accounting firm, in 1980 and is a Certified Public Accountant. Mr. Beshar has served as a director and chair of the Washington officeaudit committee at Trillium Therapeutics Inc., a publicly held immuno-oncology company, since March 2014, a director at EnteraBio Ltd. (“EnteraBio”), a privately held biopharmaceutical company, since December 2015 and Executive Chairman of the law firmboard of Kaye Scholer. Whiledirectors at EnteraBio since December 2016. Mr. Beshar holds a B.S. degree in Accounting and Finance from Michigan State University and is a graduate of The Executive Program at the Darden Graduate School of Business at the University of Virginia. Mr. Beshar’s qualifications to serve as a member of the Board include his financial and managerial experience in the biotechnology and life sciences industries, including serving as Chief Financial Officer, his financial and accounting expertise and his prior service on public sector,and private company boards.

Kenneth T. Mills has been our President, Chief Executive Officer and Director since March 2009. Mr. FoxMills was with FOXKISER LLP (“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. (“IGEN”), a biotechnology company, where he served as ChiefDirector of StaffBusiness 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 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 Legislative AssistantExecutive 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 U.S. Senator Jacob K. JavitsDecember 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 New York.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 member of the boards of directors at Sunesis Pharmaceuticals, Inc. since June 2006, MacroGenics, Inc. since September 2013 and Portola Pharmaceuticals, Inc. since September 2015, each of which is a publicly held biopharmaceutical company. He also currently serves on the board of trustees of Earlham College. Dr. Stump previously served as Chief Counsela director at 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 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. FoxUniversity of Iowa. Dr. Stump has specific

attributes that qualify him to serve as a member of ourthe Board, of Directors, including his substantial medical and scientific background and expertise, his extensive experience in research and development and operations in the biotechnology sectorindustry and FDA consulting, as well as his prior service on privatepublic company boards.

Camille Samuels has beenVote Required

Directors are elected by a Director since January 2015. Ms. Samuels has been a Partnerplurality of the votes cast at Venrock, a venture capital firm, since May 2014. Prior to Venrock, Ms. Samuels spent over a decade as a Managing Director at Versant Ventures, a life sciences venture capital firm, which she joined in 2000the Annual Meeting. The three nominees receiving the highest number of “For” votes will be elected. Abstentions and for which she provided services through March 2014. Ms. Samuels currently servesbrokernon-votes will have no effect on the boardoutcome of Spirox Corporation and Unity Biosciences, Inc. She previously served as a board member or a board observer on other healthcare companies including Achaogen, Inc., Fluidigm Sciences Inc., Genomic Health, Inc., Novacardia, Inc. (acquired by Merck & Co., Inc.), ParAllele BioScience, Inc. (acquired by Affymetrix Inc.), and Syrrx Inc. (acquired by Takeda Pharmaceutical Co.). Prior to her venture career, Ms. Samuels held business development and strategic marketing rolesthe election of directors at Tularik Inc. (acquired by Amgen Inc.) and Genzyme Corporation (acquired by Sanofi-Aventis SA). She also worked as a management consultant to consumer, healthcare and biotech companies at LEK Consulting. Ms. Samuels holds a B.A. in Biology from Duke University and an M.B.A. from Harvard Business School. Ms. Samuels has specific attributes that qualify her to serve as a memberthe Annual Meeting.

Recommendation of ourthe Board of Directors, including her experience in venture capital investing and in the biotechnology sector, as well as her prior service on public and private company boards and audit committees.

YOURTHE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS THAT YOUA VOTE THE PROXY CARD “FOR” THE ELECTION OF ALLAN M. FOX AND CAMILLE SAMUELS AS CLASS I DIRECTORSEACH 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 involvement in certain legal or administrative proceedings, if applicable, and the experiences, qualifications, attributes or skills that caused the Nominating and Corporate Governance Committee and ourthe Board of Directors to determine that the directors should serve as one of our directors. The ageterm of each director asthe Class I directors will expire at the 2019 annual meeting of April 18, 2016 is set forth below.stockholders, and the term of the Class II directors will expire at the 2020 annual meeting of stockholders.

Class I Directors (Terms Expire in 2019)

Daniel J. Abdun-Nabi has been a Director since August 2016. Mr. Abdun-Nabi currently serves as the Chief Executive Officer and as a director of Emergent BioSolutions Inc. (“Emergent”), a publicly held

biopharmaceutical company. From April 2012 to March 2018, Mr. Abdun-Nabi served as Emergent’s President and Chief Executive Officer, from May 2007 to March 2012, he served as Emergent’s President and Chief Operating Officer, and he held various other senior management positions at Emergent beginning in 2004. Mr. Abdun-Nabi served as General Counsel for IGEN, a biotechnology company, and its successor BioVeris Corporation, from September 1999 to May 2004. Prior to joining IGEN, Mr. Abdun-Nabi served as Senior Vice President, Legal Affairs, General Counsel and Secretary of North American Vaccine, Inc., a vaccine developer and manufacturer. Mr. Abdun-Nabi has served as a director at Aptevo Therapeutics Inc., a publicly held biotechnology company, since August 2016. Mr. Abdun-Nabi received an LL.M. in Taxation from Georgetown University Law Center, a J.D. from the University of San Diego School of Law and a B.A. from the University of Massachusetts, Amherst. Mr. Abdun-Nabi’s qualifications to continue to serve as a member of the Board include his extensive experience in senior management positions at biopharmaceutical companies, including his current position as Chief Executive Officer of a biopharmaceutical company, his prior service on public company boards and his demonstrated business judgment.

Allan M. Fox has been 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. Foxco-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 has served as a director at WindMIL Therapeutics, Inc., a privately held biotechnology company, since March 2017. 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 and his prior service on private company boards.

Class II Directors (Terms Expire in 2017)2020)

Donald J. Hayden, Jr. has been a Director and the Chairman of ourthe Board of Directors since February 2013. From 1991 to 2006, Mr. Hayden held several executive positions with Bristol-Myers Squibb Company, a biopharmaceutical company, most recently serving as Executive Vice President and President, Americas. Mr. Hayden is currently a member and chairmanhas served as Chairman of the Boardboard of Directors ofdirectors at Insmed Incorporated, a publicly held biopharmaceutical company, since December 2010, Lead Independent Director at Amicus Therapeutics, Inc. (“Amicus”), a publicly held biotechnology company, since February 2010 and Vitae Pharmaceuticals Inc. He is also lead independenta director at Amicus since March 2006. He also has served as Chairman of the board of directors at WindMIL Therapeutics, Inc., a member of the Board of Directorsprivately held biotechnology company, since January 2017 and as a director at Otsuka America Pharmaceutical, Inc., and serves as a senior advisor to Prospect Venture Partners, a leading life sciences venture capital firm.privately held U.S. subsidiary of Otsuka Pharmaceutical Co., Ltd., since January 2010. Mr. Hayden served as Chairman of the board of directors at Vitae Pharmaceuticals, Inc. from March 2006 to October 2016, and as a director ofat Dimension Therapeutics, Inc., a gene therapy company, from October 2013 to July 2015. Mr. Hayden holds a B.A. from Harvard University and an M.B.A. from Indiana University. Mr. Hayden has specific attributes that qualify him to continue to serve as a member of ourthe Board, of Directors, including his broad experience in the biotechnology and pharmaceutical industries, as well asindustry, his prior service onchairing public and private company boards, his experience helping shape new technologies, products and markets and his executive-level service at a number of publicexperience leading health care businesses in the United States and private companies.internationally.

A.N. “Jerry” Karabelas, Ph.D., has been a Director since May 2015. Since December 2001, Mr.Dr. Karabelas has been a managing memberPartner at Care Capital, II, LLC and(“Care Capital”), a life sciences venture firm, since December 2001. Prior to joining Care Capital, III, LLC (Care Capital), a provider of capital for entrepreneurial private and public companies developing pharmaceuticals. Prior to his work at Care Capital, from July 2000 to September 2001, Mr.Dr. Karabelas was Chairman at Novartis BioVentures Fund, which is owned by Novartis AG (Novartis)(“Novartis”), a provider of capital for life sciences companies across the biotech, medical devices and diagnostics

industries, prior to which Mr. Karabelashe 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 has served as a director at Valeant Pharmaceuticals International, Inc., a publicly held specialty pharmaceutical and medical device company, since June 2016, a director at Braeburn Pharmaceuticals, Inc., a privately held pharmaceutical company, since September 2015 and Chairman of the board of directors at Polyphor AG, a privately held pharmaceutical company, since June 2013. He served as Chairman of the board of directors at Inotek Pharmaceuticals Corporation from July 2012 to June 2016. In connection with his work at Care Capital, Mr.Dr. Karabelas haspreviously served on numerous boards of directors of pharmaceutical and therapeutics companies, including Renovo, plc, Vanda Pharmaceuticals, Inc. and NitroMed, Inc. Since June 2013, Mr.Dr. Karabelas hasalso previously served as Chairman of Polyphor AG. Mr. Karabelas also served as a member of the boardsboard of directors ofat SkyePharma, plc from May 2001 to May 2009 and Human Genome Sciences. Mr.Dr. Karabelas received a B.S. from the University of New Hampshire and a Ph.D. from the Massachusetts College of Pharmacy. Mr.Dr. Karabelas has specific attributes that qualify him to continue to serve as a member of ourthe Board, of Directors, including his extensive experience in working with publicly held pharmaceuticalssenior management positions at biopharmaceutical companies, advising developinghis strong knowledge of strategic and regulatory issues, his insight into international operations and his international perspective on the life sciences therapeuticsindustry and pharmaceuticals companies and his executive leadership, managerial and business experience.

Class III Directors (Terms Expire in 2018)healthcare related issues.

Luke M. BesharDaniel Tassé has been a Director since April 2015.August 2016. Mr. Beshar wasTassé is currently the Executive/Senior Vice PresidentChairman and Chief FinancialExecutive Officer of NPS Pharmaceuticals,Alcresta Therapeutics, a company developing and commercializing therapies for patients with gastrointestinal disorders associated with rare diseases. Mr. Tassé has served as a director at Bellerophon Therapeutics, Inc. (“Bellerophon”), a globalpublicly held biopharmaceutical company, from November 2007 to February 2015. Hesince December 2013, Indivior PLC (where he is the Lead Independent Director), a former Chief Financial Officer of various publicLondon Stock Exchange publicly traded pharmaceutical company, since August 2014 and private companies and has more than 30 years of general and financial management experience. Mr. Beshar served as Executive Vice President and Chief Financial Officer of Cambrex Corporation fromBioQ Pharma, a privately held pharmaceutical company, since December 2002 to November 2007, a global life sciences company, and previously as Senior Vice President and Chief Financial Officer at Dendrite International, a leading provider of services2014. Prior to the life sciences industry.acquisition of Ikaria Inc. (“Ikaria”) by Mallinckrodt Pharmaceuticals in April 2015, Mr. Beshar began his career with Arthur Andersen & Co. in 1980 and is a Certified Public Accountant. Mr. Beshar is a Director of Trillium Therapeutics, Inc. and Chair of its Audit Committee, a Director and member of the Audit Committee of Sancilio Pharmaceuticals Company, Inc., and a Director of EnteraBio Ltd. Mr. Beshar holds a B.S. degree in Accounting and Finance from Michigan State University and is a graduate of The Executive Program at the Darden Graduate School of Business at the University of Virginia. Mr. Beshar has specific attributes that qualify him to serve as a member of our Board of Directors, including his experience in the biotechnology and medical industries, his financial and accounting expertise, as well as his prior service on public and private company boards.

Kenneth T. Mills has been ourTassé was President, Chief Executive Officer and Director since March 2009.Chairman of Ikaria and served as the Interim Chief Executive Officer and President of Bellerophon from February 2014 to June 2014. Previously, Mr. MillsTassé was with FoxKiser, most recently asthe General Manager of the Pharmaceuticals and Technologies Business Unit of Baxter International, Inc., a partner, from January 2007 to January 2015. Mr. Mills was previously the Chief Financial Officerhealthcare company, and Vice President of Business Developmentand Regional Director for Australasia at Meso Scale Diagnostics,GlaxoSmithKline plc, a privately-held life sciences company from January 2004 to December 2006 andpharmaceutical company. Mr. Tassé was parta member of the original management team that establishedHealth Section Governing Board of the company’s operations and financing strategy. From March 1997 to December 2003, Mr. Mills was employed at IGEN International, a medical diagnostics company,Biotechnology Industry Organization, where he served as Director of Business Development up throughparticipated on the company’s acquisition by Roche.bioethics, regulatory environment and reimbursement committees. Additionally, Mr. Mills received an S.B. in Chemistry from the Massachusetts Institute of Technology. We believe that Mr. Mills’ qualifications to serve as a director of our company include his extensive experience as an executive in the gene therapy and biotechnology industries and his prior service as a senior-level executive in both early stage and mature biotechnology companies.

David C. Stump, M.D. has been a Director since October 2015. From November 1999 to December 2012, Dr. StumpTassé was with Human Genome Sciences, Inc., 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 is a member of the board of directors of Sunesis Pharmaceuticals, Inc.,

MacroGenics, Inc.the Pharmaceutical Research and Portola Pharmaceuticals, Inc. and a memberManufacturers of the board of trustees of Earlham College. Dr. Stump previously servedAmerica, where he participated on the board of directors of Dendreon Corporation. Dr. Stump holds an A.B.FDA and biomedical research committee. Mr. Tassé received a B.Sc. in Biochemistry from Earlham College and an M.D. from Indiana University and did his residency and fellowship training in internal medicine, hematology, oncology and biochemistry at the University of Iowa. Dr. StumpMontreal. Mr. Tassé has specific attributes that qualify him to continue to serve as a member of ourthe Board, of Directors, including his scientificextensive track record of business building in the healthcare industry, his strong background within critical care, his global management experience and clinical expertise and industry background, as well as his prior service on company boards.detailed knowledge of the life sciences industry.

CORPORATE GOVERNANCE

IndependenceOur 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 Governance Guidelines

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

Code of Business Conduct

We maintain a code of business conduct that qualifies as a “code of ethics” under Item 406 of the SEC’sRegulation 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 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) payments to government personnel; and (14) the reporting of illegal and unethical behavior.

The code of business conduct is available in the corporate governance section of our corporate website at www.regenxbio.com. Any amendment or waiver of the “code of ethics” provisions of the code of business conduct 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 report filed with the SEC onForm 8-K or on our corporate website at www.regenxbio.com.

Director Independence

As required under NASDAQNasdaq 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 hissuch director’s family members, and the Company, its senior management and its independent registered public accounting firm, the Board of Directors has determined that all of our directors are independent directors within the meaning of applicable NASDAQNasdaq listing standards, except for Mr.Kenneth T. Mills, our President and Chief Executive Officer, and Allan M. Fox and Donald J. Hayden, Jr. Our Board of Directors currently expects that Donald Hayden, Jr. will qualify as an independent director in accordance with the rules of NASDAQ commencing during the fourth quarter of 2016.Fox.

Information Regarding the Board of Directors and its Committees

As required under NASDAQNasdaq listing standards, our independent directors meet in regularly scheduled executive sessions at which only independent directors are present, noting that we have relied on Nasdaq Marketplace Rule 5615(b)(1), a “phase-in” rule for companies following their initial public offerings, in allowing Donald J. Hayden, Jr., Chairman of thepresent.

The Board of Directors, to be present and preside over these executive sessions.

Our Board of Directors 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 2015:2017:

Below is a description of each committee of the Board of Directors.Board. The Board of Directors 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 individual exercise of independent judgment with regard to the Company.

Audit CommitteeCode of Business Conduct

We maintain a code of business conduct that qualifies as a “code of ethics” under Item 406 of the SEC’sRegulation 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 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) payments to government personnel; and (14) the reporting of illegal and unethical behavior.

The Audit Committeecode of the Board of Directors 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: (1) appointing, approving the compensation of, and assessing the independence of our registered public accounting firm; (2) overseeing the work of our registered public accounting firm, including through the

receipt and consideration of reports from such firm; (3) reviewing and discussing with management and the registered public accounting firm our annual and quarterly financial statements and related disclosures; (4) monitoring our internal control over financial reporting and our disclosure controls and procedures; (5) meeting independently with our registered public accounting firm and management; (6) furnishing the audit committee report required by SEC rules; (7) reviewing and approving or ratifying any related person transactions; and (8) overseeing our risk assessment and risk management policies. Our Audit Committee charter can be foundbusiness conduct is available in the corporate governance section of our corporate website at www.regenxbio.com.

Three directors comprised the Audit Committee as of December 31, 2015: Mr. Beshar (the Chairman Any amendment or waiver of the Audit Committee), Dr. Stump and Ms. Samuels. The Audit Committee met four times during 2015. Effective October 14, 2015, Dr. Stump became a member“code of ethics” provisions of the Audit Committeecode of business conduct for an executive officer or director may be granted only by the Board or a committee thereof and Mr. Hayden resignedmust 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 memberreport filed with the SEC onForm 8-K or on our corporate website at www.regenxbio.com.

Director Independence

As required under Nasdaq listing standards, a majority of the Audit Committee.

All members of our Audit Committee meeta listed company’s board of directors must qualify as “independent,” as affirmatively determined by the requirements for financial literacy underboard 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 applicable rulesCompany, its senior management and regulations ofits independent registered public accounting firm, the SEC and NASDAQ. Our Board of Directors has determined that Mr. Beshar is an “audit committee financial expert” as defined by applicable SEC rules and has the requisite financial sophistication as defined under the applicable NASDAQ rules and regulations.

The Board of Directors 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 Exchange Act).

Compensation Committee

The Compensation Committee of the Board of Directors reviews and approves the design 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: (1) evaluating the performance of our chief executive officer and determining the chief executive officer’s salary and contingent compensation based on his or her performance and other relevant criteria; (2) identifying the corporate and individual objectives governing the chief executive officer’s compensation; (3) approving the compensation of our other executive officers; (4) making recommendations to our board with respect to director compensation; (5) reviewing and approving the terms of material agreements between us and our executive officers; (6) overseeing and administering our equity incentive plans and employee benefit plans; (7) reviewing and approving policies and procedures relating to the perquisites and expense accounts of our executive officers; (8) preparing the annual Compensation Committee report required by SEC rules; and (9) conducting a review of executive officer succession planning, as necessary, reporting its findings and recommendations to our Board of Directors, and working with the Board in evaluating potential successors to executive officer positions. In accordance with NASDAQ listing standards and our amended and restated Compensation Committee charter, our Board of Directors 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 comprised the Compensation Committee of the Board of Directors as of December 31, 2015: Mr. Hayden (the Chairman of the Compensation Committee), Mr. Beshar and Ms. Samuels. The Compensation Committee met three times during 2015.

The Board of Directors has determined that all members of the Compensation Committee are independent (as independence is currently defined in the NASDAQ listing standards) other than Mr. Hayden. However, we

are permitted to phase-in our compliance with the independent compensation committee requirements set forth in the rules of NASDAQ and the Exchange Act, which would require the compensation committee to be compromised of all independent members within one year of listing. We expect that, within one year of our listing on NASDAQ, Mr. Hayden will have resigned from our compensation committee. At such time, we may appoint an independent director (as determined under the listing standards of NASDAQ and Exchange Act rules) to our compensation committee or have two directors serve on the committee. Our Board of Directors currently expects that Mr. Hayden will qualify as an independent director in accordance with the rules of NASDAQ commencing during the fourth quarter of 2016. In addition, each of our directors serving on our Compensation Committee satisfiesare independent directors within the heightened independence standards for membersmeaning of a compensation committee under NASDAQapplicable Nasdaq listing standards, each member of this committee is a non-employee director, as defined pursuant to Rule 16b-3 promulgated under the Exchange Act,except for Kenneth T. Mills, our President and an outside director, as defined pursuant to Section 162(m) of the Internal Revenue Code of 1986, as amended (the Code).

Our Chief Executive Officer, often participates in the Compensation Committee’s meetings. He does not participate in the determination of his own compensation or the compensation of directors. However, Mr. Mills does make 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 their compensation. No other executive officers participate in the determination of the amount or form of the compensation of executive officers or directors.Allan M. Fox.

The Compensation Committee has retained Radford, a compensation consulting firm, since May 2015. In February 2016, Radford presented a new executive compensation report to the Compensation Committee. Radford provided the Compensation Committee with data about the compensation paid by our peer group of companies 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 jurisdiction and was available to advise the Compensation Committee regarding all of its responsibilities. The consultant serves at the pleasure of the Compensation Committee rather than the Company, and the consultant’s fees are approved by the Compensation Committee. In February 2016, our Compensation Committee assessed the independence of Radford pursuant to applicable SEC rules and NASDAQ listing standards and concluded that the work of Radford has not raised any conflict of interest.

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 of Directors or our Compensation Committee.

Nominating and Corporate Governance Committee

Our Nominating and Corporate Governance Committee identifies, evaluates and recommends nominees to our Board of Directors and committees of our Board of Directors, conducts searches for appropriate directors, and evaluates the performance of our Board of Directors and of individual directors. Pursuant to the Nominating and Corporate Governance Committee charter, the functions of the Nominating and Corporate Governance Committee include, among other things: (1) identifying, evaluating, and making recommendations to our Board of Directors and our stockholders concerning nominees for election to our board, to each of the board’s committees and as committee chairs; (2) annually reviewing the performance and effectiveness of our board and developing and overseeing a performance evaluation process; (3) annually evaluating the performance of management, the board and each board committee against their duties and responsibilities relating to corporate governance; (4) annually evaluating adequacy of our corporate governance structure, policies, and procedures; and (5) providing reports to our board regarding the committee’s nominations for election toInformation Regarding the Board of Directors and its committees. OurCommittees

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 charter can be found inCommittee. The following table provides membership and meeting information for each of the corporate governance sectionBoard committees during 2017:

Below is a description of our website at www.regenxbio.com.

Three directors comprisedeach committee of the Board. The Board has determined that each member of the Audit, Compensation and Nominating and Corporate Governance Committee as of December 31, 2015: Dr. Karabelas (the Chairman of the Nominating and Corporate Governance Committee), Dr. Engleman and Dr. Stump. Dr. Engleman has informed the Board of Directors that he will not stand for re-election and his term will expire on June 1, 2016 at the Annual Meeting. Following such time, the Nominating and Corporate Governance Committee will be comprised of two directors. The Nominating and Corporate Governance Committee met two times during 2015.

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 committee considers diversity, age, skills, and such other factors as it deems appropriate given the then-current needs of the Board of Directors and the Company, to maintain a balance of knowledge, experience and capability. While diversity and variety of experiences and viewpoints represented on the Board of Directors should always be considered, the Nominating and Corporate Governance Committee believes that a director nominee should not be chosen nor excluded solely or largely because of race, color, gender, national origin or sexual orientation or identity.

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.

When there is a vacancy on the Board of Directors, 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 of Directors. The Nominating and Corporate Governance Committee meets to discuss and consider such candidates’ qualifications and then selects a nominee for recommendation to the Board of Directors by majority vote.

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 of Directors or the Nominating and Corporate Governance Committee for consideration. If a stockholder of the Company wishes to recommend a director candidate for consideration by the Nominating and Corporate Governance Committee, the

stockholder recommendation should be delivered to the Corporate Secretary of the Company at the principal executive offices of the Company pursuant to the terms and conditions of our amended and restated bylaws. The stockholder recommendation must, among other things, set forth:

In addition, our amended and restated bylaws requireany relationship that the stockholder recommendation shall set forth as to each person whom the stockholder proposes to nominate for election or reelection as a director (1) the name, age, business address and residence addresswould interfere with his individual exercise of the person; (2) the principal occupation or employment of the

person; (3) the class, series and number of shares of capital stock of the Company that are owned beneficially and of record by the person; (4) a statement asindependent judgment with regard to the person’s citizenship; (5) the completed and signed representation and agreement described above; (6) any other information relating to the person that is required to be disclosed in solicitations for proxies for election of directors pursuant to Section 14 of the Exchange Act; (7) such person’s written consent to being named in the proxy statement as a nominee and to serving as a director if elected; and (8) whether and the extent to which any derivative instrument, swap, option, warrant, short interest, hedge or profit interest or other transaction has been entered into by or on behalf of such person with respect to stock of the Company and whether any other agreement, arrangement or understanding (including any short position or any borrowing or lending of shares of stock) has been made by or on behalf of such person, the effect or intent of any of the foregoing being to mitigate loss to, or to manage risk of stock price changes for, such person or to increase or decrease the voting power or pecuniary or economic interest of such person with respect to stock of the Company.

We believe that each of our directors and nominees brings a strong background and set of skills to our Board of Directors, giving the Board of Directors, as a whole, an appropriate balance of the knowledge, experience, attributes, skills and expertise. In addition, four of our seven continuing directors are independent under NASDAQ standards (Mr. Mills, our Chief Executive Officer, Allan M. Fox and Donald J. Hayden, Jr. being the exceptions) and our Nominating and Corporate Governance Committee believes that all seven continuing 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 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 our board committees. As described above, the Nominating and Corporate Governance Committee recommends new members of our Board of Directors for their directorships. In evaluating such directors, 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 our Board of Directors 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 our Board of Directors 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 of Directors 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.

Disclosure Committee and Committee Charter

We have a Disclosure Committee and Disclosure Committee charter. Our Disclosure Committee is comprised of our Chief Executive Officer; Chief Financial Officer; Chief Medical Officer; General Counsel; and certain other senior-level executive officers. Our General Counsel serves as the chair of the Disclosure Committee. The purpose of the Disclosure Committee is to provide assistance to the Chief Executive Officer and the Chief Financial Officer in fulfilling their responsibilities regarding the identification and disclosure of material information about us, and the accuracy, completeness and timeliness of our financial reports. Our Disclosure Committee meets at least once per quarter.

Separation of CEO and Chairman of the Board Roles

Our Board of Directors separates the positions of Chairman of the Board and Chief Executive Officer. Separating these positions allows our Chief Executive Officer to focus on our day-to-day business, while

allowing the Chairman of the Board to lead the Board of Directors in its fundamental role of providing advice to and independent oversight of management. The Board of Directors recognizes the time, effort, and energy that the Chief Executive Officer 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 of Directors’ 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.

Meetings of the Board of Directors

Our Board of Directors met 13 times during 2015. Each director attended 75% or more of the aggregate of the meetings of the Board of Directors and of the committees on which he or she served, held during the period for which he was a director or committee member.

Director Attendance at Annual Meetings of Stockholders

Directors are encouraged, but not required, to attend our annual stockholder meetings.

Stockholder Communications with the Board of Directors

Stockholders may communicate with the Board of Directors, including the independent members of the Board of Directors, by sending a letter to the Corporate Secretary, REGENXBIO Inc., 9712 Medical Center Drive, Suite 100, Rockville, MD 20850. Each such communication should set forth (1) the name and address of such stockholder, as they appear on the Company’s books and, if the shares of the Company’s stock are held by a nominee, the name and address of the beneficial owner of such shares, and (2) the number of shares of the Company’s stock that are owned of record by such record holder and beneficially by such beneficial owner. The Corporate Secretary will review all communications from stockholders, but may, in her sole discretion, disregard any communication that she believes is not related to the duties and responsibilities of the Board of Directors. If deemed an appropriate communication, the Corporate Secretary will submit a stockholder communication to a chairman of a committee of the Board of Directors, or a particular director, as appropriate.

Code of Business Conduct

We have adoptedmaintain a code of business conduct that qualifies as a “code of ethics” under Item 406 of the SEC’sRegulation S-K and applies to each of our directors, officers and employees, including our principal executive officer, principal financial officer, principal accounting officer orand controller, andor persons performing similar functions. The code of business conduct 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) payments to government personnel; and (14) the reporting of illegal and unethical behavior.

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

We have implemented whistleblower proceduresDirector 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 establish formal protocolsall of our directors are independent directors within the meaning of applicable Nasdaq listing standards, except for receivingKenneth T. Mills, our President and handling complaints from employees. Any concernsChief Executive Officer, 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 2017:

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 accounting or audit matters reported under these procedures will be communicated promptly“independence” and that each such member is free of any relationship that would interfere with his 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.Committee charter, the functions of the Audit Committee include, among other things: (1) appointing, approving the compensation of, and assessing the independence of our registered public accounting firm; (2) overseeing the work of our registered public accounting firm, including through the receipt and consideration of reports from such firm; (3) reviewing and discussing with management and the registered public accounting firm our annual and quarterly financial statements and related disclosures; (4) monitoring our internal control over financial reporting and our disclosure controls and procedures; (5) meeting independently with our registered public accounting firm and management; (6) furnishing the audit committee report required by SEC rules; (7) reviewing and approving or ratifying any related person transactions; and (8) overseeing our risk assessment and risk management policies. Our Audit Committee charter can be found in the corporate governance section of our corporate website at www.regenxbio.com.

Three directors comprised the Audit Committee as of December 31, 2017: Mr. Beshar (the Chairman of the Audit Committee), Mr. Abdun-Nabi and Dr. Stump. The whistleblower policyAudit Committee met seven times during 2017.

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 each of Messrs. Abdun-Nabi and Beshar is postedan “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 andRule 10A-3 promulgated under the Exchange Act).

Compensation Committee

The Compensation Committee of the Board reviews and approves the design 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: (1) evaluating the performance of our chief executive officer and determining the chief executive officer’s salary and contingent compensation based on his or her performance and other relevant criteria; (2) identifying the corporate and individual objectives governing the chief executive officer’s compensation; (3) approving the compensation of our other executive officers; (4) making recommendations to the Board with respect to director compensation; (5) reviewing and approving the terms of material agreements between us and our executive officers; (6) overseeing and administering our equity incentive plans and employee benefit plans; (7) reviewing and approving policies and procedures relating to the perquisites and expense accounts of our executive officers; (8) preparing the annual Compensation Committee report required by SEC rules; and (9) conducting a review of executive officer succession planning, as necessary, reporting its findings and recommendations to the Board, and working with the Board in evaluating potential successors to executive officer positions. In accordance with Nasdaq listing standards and our amended and restated 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 comprised the Compensation Committee of the Board as of December 31, 2017: Mr. Hayden (the Chairman of the Compensation Committee), Mr. Beshar and Mr. Tassé. The Compensation Committee met eight times during 2017.

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, is anon-employee director, as defined pursuant toRule 16b-3 promulgated under the Exchange Act, and is an outside director, as defined pursuant to Section 162(m) of the Internal Revenue Code of 1986, as amended (the “Code”).

Our Chief Executive Officer often participates in the Compensation Committee’s meetings. He does not participate in the determination of his own compensation or the compensation of directors. However, our Chief Executive Officer does make 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. No other executive officers participate in the determination of the amount or form of the compensation of executive officers or directors.

The Compensation Committee has retained Radford, a compensation consulting firm, since May 2015. Radford is a business unit of Aon. Radford provided the Compensation Committee with data about the compensation paid by our peer group of companies 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 jurisdiction and was available to advise the Compensation Committee regarding all of its responsibilities. Radford continues to present compensation reports to the Compensation Committee on a regular basis. The consultant serves at the pleasure of the Compensation Committee rather than the Company, and the consultant’s fees are approved by the Compensation Committee. In February 2018, our Compensation Committee assessed the independence of Radford pursuant to applicable SEC rules and Nasdaq listing standards and concluded that the work of Radford has not raised 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 and of individual directors. Pursuant to the Nominating and Corporate Governance

Committee charter, the functions of the Nominating and Corporate Governance Committee include, among other things: (1) identifying, evaluating, and making recommendations to the Board and our stockholders concerning nominees for election to the Board, to each of the Board’s committees and as committee chairs; (2) annually reviewing the performance and effectiveness of the Board and developing and overseeing a performance evaluation process; (3) annually evaluating the performance of management, the Board and each Board committee against their duties and responsibilities relating to corporate governance; (4) annually evaluating adequacy of our corporate governance structure, policies, and procedures; and (5) providing reports to the Board regarding the Nominating and Corporate Governance Committee’s nominations for election to the Board and its committees. Our Nominating and Corporate Governance Committee charter can be found in the corporate governance section of our website at www.regenxbio.com.

Two directors comprised the Nominating and Corporate Governance Committee as of December 31, 2017: Dr. Karabelas (the Chairman of the Nominating and Corporate Governance Committee) and Dr. Stump. The Nominating and Corporate Governance Committee met four times during 2017.

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 the knowledge, experience, attributes, skills and expertise. In addition, six of our eight directors are independent under Nasdaq standards (Mr. Mills, our President and Chief Executive Officer, and Mr. Fox being the exceptions) and our Nominating and Corporate Governance Committee believes that all eight 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 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.

Diversity

The Board does not have a formal policy with respect to diversity. However, 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 the Company’s stockholders.

Board Renewal

The Board believes it is important to have experienced directors with a deep understanding of the Company’s business as well as other 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 two new independent directors within the past two years.

In recruiting new independent directors, the Board or the Nominating and Corporate Governance Committee may retain a search firm to help identify director prospects, perform candidate outreach, assist in reference and background checks and provide other related services. The recruiting process typically involves either the search firm or a member of the Board or the Nominating and Corporate Governance Committee contacting 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 10 times during 2017. 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 was a director or committee member.

Directors are encouraged, but not required, to attend our annual meetings of stockholders. Seven of our eight then-continuing directors attended our 2017 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 effectively. 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 Nomination

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 for consideration. 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., 9600 Blackwell Road, Suite 210, 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 information 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 Chief Executive Officer. Separating these positions allows our Chief Executive Officer to focus on ourday-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 Chief Executive Officer 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.

Risk Oversight

OurThe Board of Directors has responsibility for the oversight of the company’sCompany’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 ourthe Board of Directors receiving regular reports from boardBoard committees and members of senior management to enable ourthe Board of Directors to understand the company’sCompany’s risk identification, risk management and risk mitigation strategies with respect to areas of potential material risk, including operations, finance, legal, regulatory, strategic, reputational and reputationalcybersecurity 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 Audit Committee reviews information regarding liquidity and operations, and oversees our management of financial risks. Periodically, the Audit Committee reviews our policies with respect to risk assessment, risk management, loss prevention and regulatory compliance. Oversight by the Audit Committee includes direct communication with our external auditors,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. The Nominating and Corporate Governance Committee manages risks associated with the independence of the Board, of Directors, corporate disclosure 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 of Directors is regularly informed through committee reports about such risks. Matters of significant strategic risk are considered by ourthe Board of Directors 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 (or members) of the Board or any committee of the Board, thenon-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

DIRECTOR COMPENSATION

During our fiscal year ended December 31, 2015, we paid cash feesauditing matters. Any such correspondence should be addressed to the appropriate person or persons, either by name or title, and granted options to purchase shares of our common stocksent to our non-employee directors who served on our Board of Directors. A non-employee director is a director whoCorporate Secretary at REGENXBIO Inc., 9600 Blackwell Road, Suite 210, 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 employedrelated 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.

DIRECTOR COMPENSATION

Our Board determines the compensation of ournon-employee directors in conjunction with recommendations made by usthe Compensation Committee. We use a combination of cash and who does not receiveshare-based compensation from us (other than for services as a director) or have a business relationship with us that would require disclosure under certain SEC rules.to attract and retain qualified candidates to serve on the Board. Kenneth T. Mills, our presidentPresident and chief executive officerChief Executive Officer and a member of ourthe Board, of Directors, did not receive any compensation from us during our fiscal year ended December 31, 20152017 for his service as a director and is not included in the table2017 Director Compensation Table below.

As of December 31, 2015, the following non-employee directors held outstanding options to purchase shares of our common stock: Mr. Hayden (475,475 shares); Mr. Beshar (89,375 shares); Dr. Karabelas (49,375 shares); Dr. Engleman (25,000 shares); Mr. Fox (25,000 shares); Ms. Samuels (25,000 shares) and Dr. Stump (25,000 shares).Fees Earned or Paid in Cash

Non-Employee Director Compensation

OurThe Board, of Directors, upon the recommendation of our Compensation Committee, has adopted a compensation program fornon-employee directors in August 2015. directors. Pursuant to the program, each member of ourthe Board of Directors who is not our employee will receivereceives the following annual cash compensation for boardBoard services, as applicable:

Each of the above isapplicable, paid in quarterly installments in arrears.arrears:

Option Awards

Non-employee members of ourthe Board of Directors receive automatic grants ofnon-statutory stock options under our 2015 Equity Incentive Plan. Eachnon-employee director upon joining ourthe Board of Directors willis automatically be granted anon-statutory stock option to purchase 25,000 shares of our common stock with an exercise price equal to the fair market value of our common stock on the grant date. Each of these options will vestvests in equal monthly installments over the 36 months following the date of the grant, and each provides for full acceleration in the event of a change of control.

In addition, on the date of each annual meeting of our stockholders, eachnon-employee director willis automatically be granted anon-statutory stock option to purchase 12,500 shares of our common stock with an exercise price equal to the fair market value of our common stock on the grant date. Anon-employee director who receives an initial award will not receive the additional annual award in the same calendarfor that year. The annual grants vest in equal monthly installments over the 12 months following the date of the grant, and each provides for full acceleration in the event of a change of control.

Other Compensation

We will also continue to reimburse ournon-employee directors for their reasonableout-of-pocket expenses incurred in attending boardBoard and committee meetings. We also provide customary director and officer insurance for all directors.

Pursuant

2017 Director Compensation Table

The following table sets forth a summary of the compensation we paid to ournon-employee directors in 2017:

As of December 31, 2017, ournon-employee directors held the letter agreement he entered into with us on February 6, 2013, Mr. Hayden, the Chairman of our Board of Directors, agreed to serve as a member of our Board of Directors. In consideration of such services, we agreed to pay Mr. Hayden an annual fee of $40,000. Pursuant to his letter agreement, we issued Mr. Hayden an optionfollowing outstanding options to purchase 6,420,000 Class B Preferred Units of our predecessor limited liability company. In connection with our conversion to a C-corporation in September 2014, Mr. Hayden’s Class B Preferred Units were cancelled and Mr. Hayden received an option to purchase 354,100 shares of our common stock. We terminated the letter agreement with Mr. Hayden upon completion of our initial public offering in September 2015 (the IPO), and Mr. Hayden is compensated in accordance with the provisions of our compensation program for non-employee directors.

PROPOSAL 2:

PROPOSAL 2

RATIFICATION OF SELECTIONAPPOINTMENT OF PRICEWATERHOUSECOOPERS LLP AS OUR

INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR THE YEAR ENDING DECEMBER 31, 2016

The Audit Committee of ourthe Board of Directors has selected PricewaterhouseCoopers LLP, anPwC as our independent registered public accounting firm asto perform the audit of our independent auditorsfinancial statements for the year ending December 31, 2016,2018, and has further directed that management submit thethis selection of independent auditors for ratification by our stockholders at the Annual Meeting. PricewaterhouseCoopers LLPPwC has auditedserved as our financial statements for the years ended December 31, 2015, 2014 and 2013.independent registered public accounting firm since 2015. Representatives of PricewaterhouseCoopers LLPPwC 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 amended and restated bylawsBylaws nor other governing documents or laws require stockholder ratification of the selection of PricewaterhouseCoopers LLPPwC as our independent registered public accounting firm. However, the Audit Committee of the Board of Directors is submitting the selection of PricewaterhouseCoopers LLPPwC to the stockholders for ratification as a matter of good corporate practice. If the stockholders fail to ratify the selection, the Audit Committee of the Board of Directors will reconsider whether or not to retain PricewaterhouseCoopers LLP.PwC. Even if the selection is ratified, the Audit Committee of our Board of Directors in its discretion may direct the appointment of a different independent auditorsregistered public accounting firm at any time during the year 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, holdersthe number of a majorityvotes cast “For” Proposal 2 must exceed the number of all those outstanding shares present in person, or represented by proxy, andvotes cast either affirmatively or negatively at the Annual Meeting must vote “FOR”against Proposal 2. Abstentions and brokernon-votes will be counted towards a quorum; however, they will not be counted either “FOR”“For” or “AGAINST”“Against” the proposal and will have no effect on the proposal. BecauseWe do not expect to receive brokernon-votes on this proposal because the ratification of the appointment of the independent registered public accounting firm is a matter on which a bank, brokerbanks, brokers or other nominee isnominees are generally empowered to vote no broker non-votes are expected to exist in connection with this matter.any shares for which a beneficial owner does not provide instructions.

Independent Registered Public Accounting Firm’s Fees

The following table represents aggregate fees billed to REGENXBIOthe Company for the years ended December 31, 20152017 and December 31, 2014,2016, by PricewaterhouseCoopers LLP,PwC, our principal accountant.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 annual audit of our financial statements for the years ended December 31, 2017 and 2016, the consents issued for our registration statements, and securities offerings.

Audit-Related Fees

Audit-related fees consist of fees billed or incurred by PwC for due diligence services related to mergers and acquisitions rendered during the year ended December 31, 2017.

All audit fees and audit-related fees described above werepre-approved by the Audit Committee in accordance with applicable SEC requirements.

Pre-Approval Policies and Procedures

The Audit Committee’s policy is topre-approve all audit and permissiblenon-audit services rendered by PricewaterhouseCoopers LLP,PwC, our independent registered public accounting firm. The Audit Committee canpre-approve specified services in defined categories of audit services, audit-related services and tax services up to specified amounts, as part of the Audit Committee’s approval of the scope of the engagement of PricewaterhouseCoopers LLPPwC or on an individualcase-by-case basis before PricewaterhouseCoopers LLPPwC is engaged to provide a service. The Audit Committee has determined that

Recommendation of the rendering of tax-related services by PricewaterhouseCoopers LLP is compatible with maintaining the principal accountant’s independence for audit purposes. PricewaterhouseCoopers LLP has not been engaged to perform any non-audit services.Board

YOURTHE BOARD OF DIRECTORS UNANIMOUSLY RECOMMENDS YOU “FOR”A VOTE FOR“FOR” THE RATIFICATION OF PRICEWATERHOUSECOOPERS LLPTHE APPOINTMENT OF PWC AS OUR INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR THE YEAR ENDING DECEMBER 31, 20162018.

REPORT OF THE AUDIT COMMITTEE¹ REPORT

The Audit Committee of the Board of Directors consisted on December 31, 20152017 of the threenon-employee directors named below. The Board of Directors annually reviews the NASDAQNasdaq listing standards’ definition of independence for Audit Committee members (including the requirements ofRule 10A-3 promulgated under the Securities Exchange Act of 1934, as amended)Act) and has determined that each member of the Audit Committee meets that standard. Mr.Each of Daniel J. Abdun-Nabi and Luke M. Beshar serves as an audit committee financial expert in accordance with applicable SEC regulations.

The principal purpose of the Audit Committee is to assist the Board of Directors in its general oversight of ourthe Company’s accounting and financial reporting processes and audits of ourthe Company’s financial statements. The Audit Committee is responsible for selecting and engaging ourthe Company’s independent auditor and approving the audit andnon-audit services to be provided by the independent auditor. The Audit Committee’s function is more fully described in its charter, which the Board of Directors has adopted and which the Audit Committee reviews and approves on an annual basis.

OurThe Company’s management is responsible for preparing ourthe Company’s financial statements and ourfor the Company’s financial reporting process. PricewaterhouseCoopers LLP, ourPwC, the Company’s independent registered public accounting firm, is responsible for performing an independent integrated audit of ourthe 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 attesting to the effectiveness of our internal control over financial reporting.States.

The Audit Committee has also reviewed and discussed with PricewaterhouseCoopers LLPthe Company’s management the audited financial statements in ourthe Annual Report on Form 10-K for the year ended December 31, 2015 (the 10-K).Report. In addition, the Audit Committee discussed with PricewaterhouseCoopers LLPPwC those matters required to be discussed by Statement of Accounting Standards 114, as modified, as adopted by theunder applicable Public Company Accounting Oversight Board (“PCAOB”) rules or “PCAOB,” in Rule 3200T and by PCAOB Auditing Standard No. 16, Communications with Audit Committees, as may be further modified or supplemented.standards. Additionally, PricewaterhouseCoopers LLPPwC provided to the Audit Committee the written disclosures and the letter required byunder applicable PCAOB Rule 3526 “Communication with Audit Committees concerning independence” as adopted by the Public Company Accounting Oversight Board.rules or standards. The Audit Committee also discussed with PricewaterhouseCoopers LLPPwC its independence from the Company.

Based upon the review and discussions described above, the Audit Committee recommended to the Board of Directors that the audited financial statements be included in the 10-KAnnual Report for filing with the United States Securities and Exchange Commission. We haveSEC. The Audit Committee has selected PricewaterhouseCoopers LLPPwC as the Company’s independent registered public accounting firm for the year ended December 31, 2016,2018, and havehas approved submitting the selection of the independent registered public accounting firm for ratification by the Company’s stockholders.

Submitted

The material in this Audit Committee Report is not “soliciting material,” is not deemed “filed” with the SEC and is not to be incorporated by the following membersreference in any filing of the Audit Committee:Company under the Securities Act of 1933, as amended, or the Exchange Act, whether made before or after the date hereof and irrespective of any general incorporation language in any such filing.

Luke M. Beshar, Chairman

David C. Stump, M.D.

Camille Samuels

SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

The following table sets forth certain information known to us regarding beneficial ownership of our common stock as of April 7, 2016the Record Date, March 26, 2018, by:

Applicable percentage ownership is based on 26,338,329 shares of common stock outstanding at April 7, 2016.

The information in the following table below is based upon information supplied by our executive officers, directors and principal stockholders and Schedule 13Gs and 13Ds filedinformation disclosed in filings with the SEC through April 7, 2016.the Record Date. Applicable percentage ownership is based on 31,870,555 shares of common stock outstanding at the Record Date.

In computing the number of shares of common stock beneficially owned by a person or entity and the percentage ownership of that person or entity, we deemed to be outstanding all shares of common stock subject to options held by that person or entity that are currentlywere exercisable as of the Record Date or releasable or that will become exercisable or releasablemay be exercised within 60 days of April 7, 2016.after the Record Date. We did not deem thesesuch shares outstanding, however, for the purpose of computing the percentage ownership ofbeneficially owned by any other person.person or entity. Unless otherwise indicated, the principal address of each of the stockholders below is c/o REGENXBIO Inc., 9712 Medical Center Drive,9600 Blackwell Road, Suite 100,210, Rockville, MDMaryland 20850.

Name and Address of Beneficial Owner		Number of Shares Beneficially Owned(1)				Percent of Class Outstanding
Holders of More than 5%:
Entities Affiliated with Allan M. Fox(2) 1701 Pennsylvania Ave., NW, Suite 900 Washington, DC 20006			3,221,048				10.1	%
BlackRock, Inc.(3) 55 East 52nd Street New York, NY 10055			2,284,506				7.2	%
Entities Affiliated with John Daniel Kiser(4) 1701 Pennsylvania Ave., NW, Suite 900 Washington, DC 20006			2,280,110				7.2	%
FMR LLC(5) 245 Summer Street Boston, MA 02210			2,091,594				6.6	%
Entities Affiliated with Venrock Partners(6) 3340 Hillview Avenue Palo Alto, CA 94304			1,991,907				6.2	%
Directors (Including Nominees) and Named Executive Officers:
Daniel J. Abdun-Nabi(7)			27,083				*
Luke M. Beshar(8)			114,375				*
Allan M. Fox(9)			3,268,270				10.2	%
Donald J. Hayden, Jr.(10)			380,475				1.2	%
A.N. “Jerry” Karabelas, Ph.D.(11)			74,375				*
Kenneth T. Mills(12)			940,230				2.9	%
David C. Stump, M.D.(13)			46,528				*
Daniel Tassé(14)			27,083				*
Olivier Danos, Ph.D.(15)			27,083				*
Vittal Vasista(16)			473,537				1.5	%
All directors, nominees and executive officers as a group (13 persons)(17)			5,754,895				16.9	%

(1)	Except as indicated otherwise, all persons have represented to the Company that they exercise sole voting power and sole investment power with respect to their shares.

(2)

Consists of 443,700 shares of common stock held by FoxKiser Holdings, LLC (“Holdings”), 722,485 shares of common stock held by The Allan M. Fox Trust (U/A/D April 21, 2015) (the “Fox Trust”) and 2,054,863 shares of common stock held by The Allan M. Fox Revocable Trust. Mr. Fox holds shared voting power and shared investment power over the shares held by Holdings described in the foregoing sentence with John Daniel Kiser, with Mr. Fox having a 60% interest in Holdings. Mr. Kiser is the trustee of the Fox Trust and holds sole investment power over such trust.

(3)

Based solely on the Schedule 13G/A filed with the SEC on January 23, 2018 by BlackRock, Inc. Various persons have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of the common stock of, the Company. No one person’s interest in the common stock of the Company is more than five percent of the total outstanding common shares.

(4)

Consists of 443,700 shares of common stock held by Holdings, 948,157 shares of common stock held by The Kiser 2012 Gift Trust (the “Kiser Gift Trust”) and 888,253 shares of common stock held by the John Daniel Kiser Revocable Trust U/A/D July 27, 2011. Mr. Kiser holds shared voting power and shared investment power over the shares held by Holdings described in the foregoing sentence with Mr. Fox, with Mr. Kiser having a 40% interest in Holdings. Mr. Fox is the trustee of the Kiser Gift Trust and holds sole investment power over such trust.

(5)

Based solely on the Schedule 13G/A filed with the SEC on February 12, 201613, 2018 by FMR LLC on behalf of itself and Abigail P. Johnson, a Director, the Vice Chairman and the Chief Executive Officer and the President of FMR LLC. Members of the Johnson family, including Abigail P. Johnson, are the predominant owners, directly or through trusts, of Series B voting common shares of FMR LLC, representing 49% of the voting power of FMR LLC. The Johnson family group and all other Series B shareholders have entered into a shareholders’ voting agreement under which all Series B voting common shares will be voted in accordance with the majority vote of Series B voting common shares. Accordingly, through their ownership of voting common shares and the execution of the shareholders’ voting agreement, members of the Johnson family may be deemed, under the Investment Company Act of 1940, to form a controlling group with respect to FMR LLC. Neither FMR LLC nor Abigail P. Johnson has the sole power to vote or direct the voting of the shares owned directly by the various investment companies registered under the Investment Company Act (“Fidelity Funds”) advised by Fidelity Management & Research Company (“FMR Co”), a wholly owned subsidiary of FMR LLC, which power resides with the Fidelity Funds’ Boards of Trustees. Fidelity Management & Research CompanyFMR Co carries out the voting of the shares under written guidelines established by the Fidelity Funds’ Boards of Trustees.

(2)

Consists of 443,700 shares of common stock held by FoxKiser Holdings, LLC (Holdings), 722,485 shares of common stock held by The Allan M. Fox Trust (U/A/D April 21, 2015) (the Fox Trust) and 2,054,863 shares of common stock held by The Allan M. Fox Revocable Trust. Mr. Fox holds shared dispositive power over the shares held by Holdings described in the foregoing sentence with John Daniel Kiser, with Mr. Fox having a 60% voting interest in Holdings. Mr. Kiser is the trustee of the Fox Trust and holds sole dispositive voting power over such trust. Mr. Fox otherwise holds sole dispositive power over the shares held by the other entities described.

(3)

Consists of 443,700 shares of common stock held by Holdings, 948,157 shares of common stock held by The Kiser 2012 Gift Trust (the Kiser Gift Trust) and 888,253 shares of common stock held by the John Daniel Kiser Revocable Trust U/A/D July 27, 2011. Mr. Kiser holds shared dispositive power over the shares held by Holdings described in the foregoing sentence with Mr. Fox, with Mr. Kiser having a 40% voting interest in Holdings. Mr. Fox is the trustee of the Kiser Gift Trust and holds sole dispositive voting power over such trust. Mr. Kiser holds sole dispositive power over the shares held by the other entities described.

(4)(6)

Based solely on the Schedule 13G filed with the SEC on February 16, 2016 consistsby Venrock Healthcare Capital Partners, L.P. (“VHCP I”), VHCPCo-Investment Holdings, LLC (“VHCPCo-Invest I”), Venrock Healthcare Capital Partners II, L.P. (“VHCP II”), VHCPCo-Investment Holdings II, LLC (“VHCPCo-Invest II”), VHCP Management, LLC (“VHCP Management”), VHCP Management II, LLC (“VHCP Management II” and collectively with VHCP I, VHCPCo-Invest I, VHCP II, VHCPCo-Invest II and VHCP Management, the “VHCP Entities”), Venrock Associates VII, L.P. (“VA7”), Venrock Partners VII, L.P. (“VP7”) and Venrock Management VII, LLC (“VM7” and together with VA7 and VP7, the “Venrock 7 Entities”). Consists of 838,956 shares of common stock held by Venrock Associates VII, L.P. (VA7),VA7, 783,474 shares of common stock held by Venrock Healthcare Capital PartnersVHCP II, L.P. (VHCP II), 247,480 shares of common stock held by VHCP Co-Investment HoldingsCo-Invest II, LLC (VHCP Co-Invest II), 69,497 shares of common stock held by Venrock Partners VII, L.P. (VP7),VP7, 44,381 shares of common stock held by Venrock Healthcare Capital Partners, L.P. (VHCP)VHCP I and 8,119 shares of common stock held by VHCP Co-Investment Holdings, LLC (VHCP Co-Invest I). Venrock Management VII, LLC (VM7, and collectively with VA7 and VP7, the Venrock 7 Entities) is the sole general partner of VA7 and VP7. VHCP Management I, LLC (VHCPM I) is the sole general partner of VHCP I and the manager of VHCP Co-Invest I. VHCP Management II, LLC (VHCPM II, and collectively with VHCPM I, VHCP Co-Invest I, VHCP Co-Invest II and VHCPM II, the VHCP Entities) is the sole general partner of VHCP II and the manager of VHCP Co-Invest II. The VHCP Entities expressly disclaim beneficial ownership over all shares held by the Venrock 7 Entities, except to the extent of their indirect pecuniary interest therein. The Venrock 7 Entities expressly disclaim beneficial ownership over all shares held by the VHCP Entities, except to the extent of their indirect pecuniary interest therein.

(5)(7)

Consists of 1,759,961 shares of common stock. Brookside Capital Management, LLC, the sole general partner of Brookside Capital Investors, L.P., which is the sole general partner of Brookside Capital Partners Fund, L.P., has voting and dispositive power with respectoptions to the shares.

(6)	Consists of 15,440purchase 27,083 shares of common stock and includes options to purchase 468,145 sharesthat were exercisable as of common stock thatthe Record Date or may be exercised within 60 days of April 7, 2016.

(7)	Consists of 115,440 shares of common stock and includes options to purchase 206,659 shares of common stock that may be exercised within 60 days of April 7, 2016 after the offering.Record Date.

(8)	Consists of options to purchase 137,380114,375 shares of common stock that were exercisable as of the Record Date or may be exercised within 60 days of April 7, 2016.after the Record Date.

(9)

Consists of 38,599See footnotes 2 and 4 above for securities ownership information relating to Mr. Fox. Includes options to purchase 47,222 shares of common stock and includes options to purchase 278,027 sharesthat were exercisable as of common stock thatthe Record Date or may be exercised within 60 days of April 7, 2016.after the Record Date.

(10)	Consists of options to purchase 58,333380,475 shares of common stock that were exercisable as of the Record Date or may be exercised within 60 days of April 7, 2016.after the Record Date.

(11)

Dr. Engleman is affiliated with Vivo Capital Fund VIII, L.P. (Vivo Fund VIII) and Vivo Capital Surplus Fund VIII, L.P. (Vivo Surplus VIII). Vivo Fund VIII’s ownership consistsConsists of 826,341options to purchase 74,375 shares of common stock and Vivo Surplus VIII’s ownership consists of 114,108 shares of common stock. Vivo Capital VIII, LLC, the sole general partner of both Vivo Fund VIII and Vivo Surplus VIII, has shared voting power and shared investment power over such securities, may be deemed to beneficially own such shares, and disclaims beneficial ownershipthat were exercisable as of the shares except to the extent of its pecuniary interests therein. Dr. Engleman disclaims beneficial ownership of the shares held by Vivo Fund VIII and Vivo Surplus Fund, except to the extent of his pecuniary interest therein. Dr. Engleman has informed the Board of Directors that he will not stand for re-election and his term will expire on June 1, 2016 at the Annual Meeting. Includes options to purchase 5,555 shares of common stock thatRecord Date or may be exercised within 60 days of April 7, 2016.after the Record Date.

(12)	See footnote 2 above for stock ownership relating to Mr. Fox. Includes options to purchase 5,555711,700 shares of common stock that were exercisable as of the Record Date may be exercised within 60 days of April 7, 2016.after the Record Date.

(13)	Consists of options to purchase 33,33346,528 shares of common stock that were exercisable as of the Record Date or may be exercised within 60 days of April 7, 2016.after the Record Date.

(14)

Consists of options to purchase 5,55527,083 shares of common stock that were exercisable as of the Record Date or may be exercised within 60 days of April 7, 2016. Ms. Samuels is affiliated with Venrock Partners. Ms. Samuels does not have voting or dispositive control overafter the shares held by the entities affiliated with Venrock Partners referenced in footnote 4 above.Record Date.

(15)	Consists of options to purchase 4,86127,083 shares of common stock that were exercisable as of the Record Date or may be exercised within 60 days of April 7, 2016.after the Record Date.

(16)

Consists of 4,330,976Includes options to purchase 316,254 shares of common stock and includes options to purchase 1,203,403 sharesthat were exercisable as of common stock thatthe Record Date or may be exercised within 60 days after the Record Date. Includes 65,000 shares of April 7, 2016.common stock that were owned jointly with Mr. Vasista’s spouse and over which Mr. Vasista held shared voting power and shared investment power as of the Record Date.

(17)

Includes options to purchase 2,146,893 shares of common stock that were exercisable as of the Record Date or may be exercised within 60 days after the Record Date. Mr. Fox holds shared dispositivevoting power and shared investment power over certain shares as described in footnotefootnotes 2 and 4 above and these shares are only counted once for the purpose of this calculation.

SECTION 16(a) BENEFICIAL OWNERSHIP REPORTING COMPLIANCE

Section 16(a) of the Exchange Act requires our directors, executive officers, and certain holders of more than 10% of our common stock to file reports regarding their ownership and changes in ownership of our securities with the SEC, and to furnish us with copies of all Section 16(a) reports that they file.

Based solely upon a review of Forms 3 and 4 and amendments thereto furnished to us and written representations provided to us by all of our directors and executive officers and certain of our greater than 10% stockholders, we believe that during the year ended December 31, 2015,2017, our directors, executive officers, and greater than 10% stockholders complied with all applicable Section 16(a) filing requirements.

EXECUTIVE OFFICERS

The names of the current executive officers of REGENXBIOthe Company and certain information about each of them as of April 18, 2016, are set forth below:

Executive Officers

Kenneth T. Mills –. For biographical information regarding Mr. Mills, our President and Chief Executive Officer and a member of our Board, see “Proposal 1: Election of Directors – Continuing Directors Not Standing for Election – Class III Directors (Terms Expire in 2018).Directors.”

Vittal “Vit” VasistaOlivier Danos, Ph.D.,, age 48,60, has been our Chief FinancialScientific Officer and Senior Vice President of Corporate Development since August 2009.March 2017. Prior to joining us, Mr. VasistaDr. 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 Principalthe Director of the Gene Therapy Consortium of the University College of London and led a gene therapy research team 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. EarlierNecker Hospital—Enfants Malades in his career, Mr. VasistaParis. He also served as the Chief Scientific Officer at Genethon and Senior Director Business Developmentof Research at Meso Scale Diagnostics,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 privately held life sciences company,Ph.D. in Biology from June 2002 to May 2006. Mr. Vasista received an M.B.A. from The Wharton Schoolthe Pasteur Institute and University of Paris Diderot and a Master in Science in Genetics and Molecular Biology 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.Paris Orsay.

Stephen Yoo, M.D.,, age 38,40, has been our Chief Medical Officer since October 2014. Prior to joining us, Dr. Yoo was Medical Science Director and Group Director of Clinical Development at AstraZeneca PLC, a biopharmaceutical company, from January 2014 to October 2014. In these roles, he led the late-phase clinical project teams while providing strategic and operational leadership to physicians and scientists. In previous roles at MedImmune, LLC, AstraZeneca’s global biologics research and development arm, from April 2010 to May 2014, Dr. Yoo provided strategic clinical leadership for early-phase programs. Earlier in his career, Dr. Yoo served as Associate Director of Clinical Development at Abbott Laboratories, healthcare company, from June 2008 to April 2010. Dr. Yoo holds an M.D. from the University of California, Los Angeles School of Medicine and a B.A. in Molecular and Cell Biology from the University of California, Berkeley.

Faraz AliVittal “Vit” Vasista, age 43,50, has been our Chief BusinessFinancial Officer since February 2016.August 2009. Prior to joining us, Mr. Ali was Vice President, Global Commercial Development and External AffairsVasista served as Principal at bluebird bioPRTM Management Consultants from May 2011 until February 2016,October 2006 to July 2009, where he led all commercial planning efforts,developed operational strategies for both private and public organizations, including engagement with payers in the U.S.development of market entry strategies, innovative business models, and Europe. From August 2001 to November 2010,operational improvements. Mr. Ali held roles of increasing global commercial responsibility at Genzyme, including Head of U.S. Marketing and Strategic Planning for the rare disease business unit. Prior to Genzyme, Mr. Ali served in leadership roles at GE Corporate and GE Healthcare. Mr. Ali holdsVasista received an M.B.A. with distinction from Harvard BusinessThe Wharton School and a B.S.at the University of Pennsylvania, an M.S. in ElectricalMechanical Engineering from Stanford University.University, and an S.B. in Mechanical Engineering from the Massachusetts Institute of Technology.

Curran Simpson, age 54,56, has been our Senior Vice President, Technical Operations since August 2015. Prior to joining us, Mr. Simpson was the Head, North AmericanRegional Supply Chain and also served as Interim Chief Operating Officer and Integration Lead withHead for North America at GlaxoSmithKline and Human Genome Sciences division of GlaxoSmithKline (HGS)plc (“GSK”), respectively,a pharmaceutical company, from December 2012 until August 2015. From July 2006 to December 2012, Mr. Simpson was the Senior Vice President, Operations at HGS,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.

Patrick J. Christmas, age 47, has been our Senior Vice President, General Counsel 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. 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. 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

20152017 Summary Compensation Table

The following table provides information concerning the compensation paid to our President and Chief Executive Officer, Kenneth T. Mills, and our next two most highly compensated executive officers during the Company’s fiscal year ended December 31, 2015.2017, Olivier Danos, Ph.D., and Vittal Vasista. We refer to each of these individuals as our named“named executive officers.officers,” or “NEOs.”

Narrative Explanation of Certain Aspects of the Summary Compensation Table

Base Salaries and Performance-Based BonusesCompensation

Pursuant to employment agreements entered into with us, as amended from time to time, each of our named executive officersNEOs is eligible to receive a base salary and an annual discretionaryincentive bonus payable in cash, stockequity or a combination and based on the achievement of individual and corporate objectives.

TheUnder our annual incentive program, the base salary and target annual performance bonus, as a percentage of base salary, for each of our named executive officersNEOs for our fiscal yearthe years ended December 31, 2015,2017 is listed in the table below:

(3)	Dr. Yoo’s annual base salary was increased to $340,000 effective following completion of the IPO and was increased to $375,000 on January 28, 2016.

(4)	On February 1, 2015, the annual base salary of Mr. Vasista was increased to $315,000 and was increased to $350,000 on January 28, 2016.

Objectives for the named executive officers’ target bonuses for our fiscal year ended December 31, 2015 included both2017 were determined by the Compensation Committee using subjective and objective goals determined in the discretion of our Board of Directors.goals. In January 2016,2018, our Compensation Committee determined that the Company achieved 110%105% of its corporate goals for the year ended December 31, 2015.2017 and determined that each of our NEOs achieved a certain percentage of his individual goals for the year ended

December 31, 2017, except that Mr. Mills’ target performance bonus was based entirely on the Company’s achievement of its corporate goals. As a result, our Compensation Committee awarded each of our named executive officersNEOs a cash bonusesbonus equal to 110%a certain portion of their respective non-prorated, post-IPOthe NEO’s target performance bonus, as reflected above in the bonus“Non-Equity Incentive Compensation” column of the 20152017 Summary Compensation Table.

Each of our named executive officers is eligibleTable above. Dr. Danos’s cash bonus was prorated to receive certain benefits ifreflect his employment is terminated under certain circumstances, as described under “Employment Agreements” below.start date with the Company in March 2017.

Equity Compensation

Since our conversion to a C-corporation, weWe have offeredgranted stock options to our employees, including our named executive officers,NEOs, as the long-term incentive component of our compensation program. We have also granted restricted stock units to our employees. We typically grant equity awardsstock options to new hires upon their commencing employment with us. Stock options allow employees to purchase shares of our common stock at a price per share equal to the fair market value of our common stock on the date of grant and may or may not be intended to qualify as “incentive stock options” for U.S. federal income tax purposes. Awards to newly hired employees generally vest with respect to 25% of the total number of shares subject to the option sharesgrant on the first anniversary of the vesting commencement date and in equal monthly installments over the following 36 months.

As described under “Outstanding Equity Awards as of December 31, 2015”“—Employment Agreements” below, certain equity awards granted to our named executive officersNEOs are subject to accelerated vesting in the event such officer is subject to an involuntary termination or if we experience a change in control.

Outstanding Equity Awards as of December 31, 20152017

The following table sets forth information regarding each outstanding and unexercised option held by each of our named executive officersNEOs as of December 31, 2015.2017. 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.

respect to an additional 7,377 shares following each month of service following such date. The continued vesting of the option with respect to 233,710 shares subject to the option (the Mills“Mills Contingent Shares)Shares”) was conditioned on our completion of a financing in which we raised gross proceeds of not less than $5,000,000 on or before January 1, 2016 (a Qualified Financing)“Qualified Financing”), which was satisfied upon the consummation of our Series C Preferred Stock financing in January 2015. As such, effective as of the closing of our Series C Preferred Stock financing, the option vested with respect to 25% of the Mills

Contingent Shares as of the vesting commencement date. The option vested with respect to 25% of the remaining Mills Contingent Shares on the one yearone-year anniversary of the vesting commencement date and, subject to the optionee providing continuous service to us,the Company, the remaining Mills Contingent Shares vest in 36 equal monthly installments thereafter.

(2)	Subject to the optionee providing continuous service to our company, the option vests 25% on completion of one year of service following the vesting commencement date and in 36 equal monthly installments thereafter.

(3)

The option vested with respect to 23,600 shares on the vesting commencement date. The option vested with respect to 35,400 shares on the one year anniversary of the vesting commencement date and vests with respect to an additional 2,950 shares following each month of service following such date. The continued vesting of the option with respect to 82,700 shares subject to the option (the Yoo Contingent Shares) was conditioned on our completion of a Qualified Financing, which was satisfied upon the consummation of our Series C Preferred Stock financing in January 2015. As such, effective as of the closing of our Series C Preferred Stock financing, the option vested with respect to 15% of the Yoo Contingent Shares as of the vesting commencement date. The option vested with respect to 25% of the remaining Yoo Contingent Shares on the one year anniversary of the vesting commencement date and, subject to the optionee providing continuous service to us, the remaining Yoo Contingent Shares vest in 36 equal monthly installments thereafter.

(4)

The option vested with respect to 72,235 shares on the vesting commencement date. The option vested with respect to 53,112 shares on the one yearone-year anniversary of the vesting commencement date and vests with respect to an additional 4,426 shares following each month of service following such date. The continued vesting of the option with respect to 140,217 shares subject to the option (the Vasista“Vasista Contingent Shares)Shares”) was conditioned on our completion of a Qualified Financing, which was satisfied upon the consummation of our Series C Preferred Stock financing in January 2015. As such, effective as of the closing of our Series C Preferred Stock financing, the option vested with respect to 25% of the Vasista Contingent Shares as of the vesting commencement date. The option vested with respect to 25% of the remaining Vasista Contingent Shares on the one yearone-year anniversary of the vesting commencement date and, subject to the optionee providing continuous service to us, the remaining Vasista Contingent Shares vest in 36 equal monthly installments thereafter. The option vested with respect to 59,533 shares on December 31, 2015 which would have otherwise vested between January 2018 and September 2018 upon achievement of two business goals and a determination by our Compensation Committee that two additional business goals were deemed to be achieved as of December 31, 2015.

Effective January 28, 2016, the compensation committee of3, 2018, our Board of DirectorsCompensation Committee granted options to purchase 225,000163,500 shares of our common stock to Mr. Mills, 75,00041,250 shares of our common stock to Dr. Danos and 55,000 shares of our common stock to Mr. Vasista and 70,000 shares of our common stock to Dr. Yoo.Vasista. The exercise price for each of the options was $13.09$35.80 per share, which was the closing price of our common stock on January 28, 20163, 2018 as reported by NASDAQ.Nasdaq. The options vest with respect to 25% on completion of one year of service following the shares of stock which are subject to the option on January 28, 2017vesting commencement date and vest in 36 equal monthly installments thereafter, providedsubject to the named executive officer providesoptionee providing continuous service to the company through such vesting dates.

20152017 Option Exercises

The following table shows the number of shares acquired upon option exercise for each named executive officerNEO during the year ended December 31, 2015.2017.

Securities Authorized for Issuance under Equity Incentive Plans

The following table provides information as of December 31, 2017 with respect to the shares of our common stock that may be issued under our existing equity compensation plans. We do not have any equity compensation plans that have not been approved by stockholders.

Employment Agreements

In connection with the IPO, our Compensation Committee retained an independent compensation consultant, Radford, to provide the committee with comparative information on executive compensation at peer group companies as well as advice on terms of employment for our named executive officers. Based on consultations with Radford, weWe have entered into new employment agreements with each of our named executive officers prior to the IPO.NEOs. Pursuant to theeach employment agreements,agreement, if we terminate the employment of our Chief Executive Officer and our other named executive officersthe respective NEO without cause or if such officerNEO voluntarily resigns for good reason, as described in the respective agreement, then eachthe NEO will be eligible to receive, contingent on his timely executing and not revoking a general release of all claims hethe NEO may have against us and on histhe NEO returning all of our property in histhe NEO’s possession, continued payment of base salary for (i) 12 months for Mr. Mills and (ii) nine months for Dr. YooDanos and Mr. Vasista. In addition, we will pay the terminated NEO a lump sum equal to the applicable Consolidated Omnibus Budget Reconciliation Act (“COBRA”) premiums for the same period of time. If a terminated named executive officerNEO obtains employment during the salary continuation period, then we will cease to be obligated to pay the terminated named executive officerNEO any further payments. In addition, we will pay the terminated named executive officer a lump sum equal to the COBRA premiums for the same period of time.

Further, ifIf we terminate the employment of our Chief Executive Officer and our other named executive officersan NEO without cause or if such officerNEO voluntarily resigns for good reason immediately prior to or during the 18 months following a change in control, as such term is defined in our 2015 Equity Incentive Plan, then eachthe NEO will be eligible to receive, contingent on histhe NEO timely executing and not revoking a general release of all claims hethe NEO may have against us and on histhe NEO returning all of our property in histhe NEO’s possession, continued payment of base salary and their target annual bonus in equal monthly installments for (i) 18 months for Mr. Mills and (ii) 12 months for Dr. YooDanos and Mr. Vasista. In

addition, we will pay the named executive officerNEO a lump sum equal to the applicable COBRA premiums for the same period of time. All outstanding unvested options that were outstanding as of the date of a change in control will vest if we or our successor terminates the employment of our Chief Executive Officer or other named executive officersan NEO without cause or if such officer voluntarily resigns for good reason during the remaining vesting period.

“Cause” means, with respect to Messrs. Mills and Vasista and Dr. Yoo:

“Good Reason” means an officer’s resignation within 12 months after one of the following conditions comes into existence without such officer’s consent, provided the officer gives us written notice of the condition within 90 days after it first comes into existence and we fail to remedy such condition within 30 days after receipt of such written notice:

In connection with their employment, each of our named executive officersNEOs entered into our standard form of proprietary information and inventions agreement. The proprietary informationagreement with us. This agreement provides that our officers are,the respective NEO is generally prohibited for one year after termination of employment from, directly or indirectly, soliciting our employees or customers, or competing against us.

Retirement Benefits

We have established a 401(k) tax-deferred savings plan, which permits participants, including our named executive officers, to make contributions by salary deduction pursuant to Section 401(k) of the Internal Revenue 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.

Employee Benefits and PerquisitesOther Compensation

Our named executive officersNEOs are eligible to participate in our health and welfare plans to the same extent as all full-time employees would be eligible generally, including reimbursement of certain medical expenses incurred by such named executive officerof the NEO or full-time employee and, if applicable, his or her eligible dependents. We pay 100%a portion of the premium cost for our group health plan for all of our employees, including our NEOs.

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 named executive officers.

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 named executive officersNEOs with any other perquisites or personal benefits.

Our employee stock purchase plan permits participants, including our NEOs, to purchase our common stock at a discount on atax-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 personal benefits (other than occasional payment of relocation expenses and severance benefits, as described above).stockholders.

Tax and Accounting Considerations

Our Compensation Committee considers tax and accounting implications in determining all elements of our compensation plans, programs and arrangements. For the 2017 taxable year, Section 162(m) of the Code generally deniesdenied a deduction to any publicly-held corporation for compensation paid in a taxable year to its named executive officers (other than the Chief Financial Officer)chief financial officer) exceeding $1.0 million, unless such compensation qualifiesqualified as performance-based compensation. Base salaries, time-vested restricted stock, time-vested retention and transition payments, and discretionary or subjectively determined bonus awards generally do not qualify as performance-based compensation. In September 2015, our stockholders approved our 2015 Equity Incentive Plan that permits usPursuant to satisfy the performance-based requirements underTax Cuts and Jobs Act of 2017 (the “TCJA”), for taxable years beginning in 2018, Section 162(m) of the Code will no longer exempt qualified performance-based compensation from its restriction on deductions, other than with respect to compensation paid pursuant to a written binding contract that was in effect on November 2, 2017. In addition, the grantTCJA provides that the chief financial officer will no longer be excluded from the named executive officers for purposes of stock options.its restriction on deductions.

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.

CERTAIN RELATIONSHIPS AND RELATED PARTY TRANSACTIONS

In addition to the compensation arrangements with directors and executive officers described elsewhere in this proxy statement,Proxy Statement, the following is a description of transactions since January 1, 20152017 to which we have been a party, in which the amount involved exceeded or will exceed $120,000, and in which any of our directors, executive officers or beneficial owners of more than five percent of our common stock, or an affiliate or immediate family member thereof, had or will have a direct or indirect material interest.

All of the transactions set forth below were approved by our Audit Committee or a majority of ourthe Board, of Directors, including a majority of the independent and disinterested members of our Board of Directors.the Board. We believe that we have executed all of the transactions set forth below on terms no less favorable to us than we could have obtained from unaffiliated third parties. It is our intention to ensure that all future transactions between us and our officers, directors and principal stockholders and their affiliates are approved by the Audit Committee or a majority of the members of ourthe Board, of Directors, including a majority of the independent and disinterested members of ourthe Board, of Directors, and are on terms no less favorable to us than those that we could obtain from unaffiliated third parties.

FoxKiserFOXKISER LLP Strategic Services Agreement

In February 2016,January 2018, we entered into a Strategic Services Agreement (the “2018 Strategic Services Agreement)Agreement”) with FoxKiser LLP (FoxKiser). FoxKiserFOXKISER, which is (i) an affiliate of Allan M. Fox, one of our directors, (ii) an affiliate of certain entities controlled by Mr. Fox which hold an aggregate of more than 5%five percent of our common stock and (iii) an affiliate of certain entities controlled by John Daniel Kiser which hold an aggregate of more than 5%five percent of our common stock. Pursuant to the 2018 Strategic Services Agreement, we incur a monthly fixed fee of $80,000$175,000 in consideration for certain strategic planning, development and regulatory services to be provided by FoxKiser.FOXKISER. The 2018 Strategic Services Agreement has an initiala term of one year and is terminable by either party, at any time, upon sixty60 days’ prior written notice to the other party.

Series D Financing

In May 2015,January 2017, we entered into a stock purchase agreementStrategic Services Agreement (the Series D Purchase Agreement)“2017 Strategic Services Agreement”) with new and existing investors, including certain of our existing stockholders at the time who were represented by members of our Board of Directors, including entities affiliated with Venrock Partners (Venrock Partners) and Beacon Bioventures Fund III Limited Partnership (Beacon Bioventures), to raise approximately $70.5 million from the sale of 7,366,849 shares of our Series D convertible preferred stock, $0.0001 par value per share (the Series D Preferred Stock), at a purchase price of $9.5699 per share (the Series D Financing).

Series C Financing

In January 2015, we entered into a stock purchase agreement (the Series C Purchase Agreement) with new and existing investors, including FoxKiser (which were subsequently transferred to trusts affiliated with Allan M. Fox and John Daniel Kiser) and Beacon Bioventures,FOXKISER, which were stockholders at the time who were represented by members of our Board of Directors, to raise approximately $30.0 million, including the conversion of approximately $3.8 millionexpired in outstanding convertible notes held by FoxKiser, from the sale of 4,631,774 shares of our Series C convertible preferred stock, $0.0001 par value per share (the Series C Preferred Stock), at a purchase price of $6.477 per share (the Series C Financing).

The following table summarizes the issuances and purchases of our preferred stock in the Series D Financing and the Series C Financing by our directors, officers or the beneficial holders of more than five percent of our capital stock or entities affiliated with them at the time of such transactions:

Amended and Restated Investors’ Rights Agreement

In connection with the closing of the Series D Financing described above, we entered into an amended and restated investors’ rights agreement (the Investors’ Rights Agreement) with our significant stockholders, including entities affiliated with FoxKiser (which were subsequently transferred to trusts affiliated with Allan M. Fox and John Daniel Kiser), FoxKiser Holdings, LLC (Holdings), Brookside Capital Partners, Venrock Partners, Beacon Bioventures, Deerfield Management and Vivo Capital. Pursuant to this agreement, we granted such stockholders certain registration rights with respect to shares of our common stock and a right of first offer with respect to future issuances of our securities. The sections other than with regard to registration rights of the Investors’ Rights Agreement terminated pursuant to its terms upon the consummation of the IPO in September 2015.

Amended and Restated Voting Agreement

In connection with the closing of the Series D Financing, we entered into an amended and restated voting agreement (the Voting Agreement), along with certain holders of our common stock and convertible preferred stock, including FoxKiser (which were subsequently transferred to trusts affiliated with Allan M. Fox and John Daniel Kiser), Holdings, Brookside Capital Partners, Venrock Partners, Beacon Bioventures, Deerfield Management and Vivo Capital. Under the terms of the Voting Agreement, the parties had agreed, subject to certain conditions, to vote their shares so as to elect as directors the nominees designated by certain of our investors, including Holdings, which designated Luke M. Beshar, Allan M. Fox, Donald J. Hayden, Jr. and A.N. “Jerry” Karabelas, Ph.D., Venrock Partners, which designated Camille Samuels, and Vivo Capital, which

designated Edgar G. Engleman, M.D. In addition, the parties to the Voting Agreement had agreed to vote their shares so as to elect our Chief Executive Officer to our Board of Directors, who is currently Kenneth T. Mills, and additional directors nominated by the Board of Directors and elected by the holders of our common stock and preferred stock. The Voting Agreement terminated immediately prior to the completion of the IPO.

Amended and Restated Right of First Refusal and Co-Sale Agreement

In connection with the closing of the Series D Financing, we entered into a right of first refusal and co-sale agreement (the First Refusal Agreement) with certain holders of our common stock and our convertible preferred stock, including FoxKiser (which were subsequently transferred to trusts affiliated with Allan M. Fox and John Daniel Kiser), Holdings, Brookside Capital Partners, Venrock Partners, Beacon Bioventures, Deerfield Management and Vivo Capital. Allan M. Fox, one of our directors, is a partner of FoxKiser and affiliated with Holdings, Camille Samuels, one of our directors, is a general partner at Venrock Partners and Edgar G. Engleman, M.D., one of our directors, is a partner at Vivo Capital.December 2017. Pursuant to the First Refusal2017 Strategic Services Agreement, the holderswe incurred a monthly fixed fee of convertible preferred stock had a right of first refusal$125,000 in consideration for certain strategic planning, development and co-sale in respect of certain sales of securitiesregulatory services provided by our founders and management team. The First Refusal Agreement terminated upon the closing of the IPO.FOXKISER.

Indemnification Agreements

We have entered, or will enter, into indemnification agreements with our directors, executive officers and certain key employees. Under these agreements, we agree to indemnify our directors, executive officers and certain key employees against any and all expenses incurred by them in connection with proceedings because of their status as one of our directors, executive officers or key employees to the fullest extent permitted by Delaware law, subject to certain limitations. In addition, these indemnification agreements provide that, to the fullest extent permitted by Delaware law, we will pay for all expenses incurred by our directors, executive officers and certain key employees in connection with a legal proceeding arising out of their service to us.

In addition, as permitted by Section 145 of the Delaware General Corporation Law, our amended and restated bylawsBylaws provide that we are authorized to enter into indemnification agreements with our directors and executive officers and we are authorized to purchase directors’ and officers’ liability insurance, which we currently maintain to cover our directors and executive officers.

Policies and Procedures for Related Party Transactions

In June 2015, weWe have adopted a related party transaction policy under which our directors and executive officers, including their immediate family members and affiliates, are not permitted to enter into a related party transaction with us without the prior consent of our Audit Committee, or other independent committee of our the

Board of Directors in the caseif it is inappropriate for our Audit Committee to review such transaction due to a conflict of interest. Any request for us to enter into a transaction with an executive officer, director or any of such persons’ immediate family members or affiliates, in which the amount involved exceeds $120,000, must first be presented to our Audit Committee for review, consideration and approval. All of our directors and executive officers are required to report to our Audit Committee any such related party transaction. In approving or rejecting the proposed agreement, our Audit Committee shall consider the relevant facts and circumstances available and deemed relevant to the Audit Committee, including, but not limited to the risks, costs, and benefits to us, the terms of the transaction, the availability of other sources for comparable services or products, and, if applicable, the impact on a director’s independence. Our Audit Committee shall approve only those agreements that, in light of known circumstances, are not inconsistent with our best interests, as our Audit Committee determines in the good faith exercise of its discretion.

Stock Options

For information regarding stock options granted to our named executive officers and directors, see “Corporate Governance – 2015 Director Compensation” and “Executive Compensation.”

NO INCORPORATION BY REFERENCE

In REGENXBIO’s filings with the SEC, information is sometimes “incorporated by reference.” This means that we are referring you to information that has previously been filed with the SEC and the information should be considered as part of the particular filing. As provided under SEC regulations, the “Report of the Audit Committee” and the “Report of the Compensation Committee”“Audit Committee Report” contained in this proxy statementProxy Statement specifically areis not incorporated by reference into any other filings with the SEC and shall not be deemed to be “soliciting material.” In addition, this proxy statementProxy Statement includes several website addresses. These website addresses are intended to provide inactive, textual references only. The information on these websites is not part of this proxy statement.Proxy Statement.

OTHER MATTERS

The Board of Directors knows of no other matters that will be presented for consideration at the Annual Meeting. If any other matters are properly brought before the Annual Meeting, it is the intention of the persons named in the accompanying proxy tocard will vote on such matters in accordance with their best judgment.

It is important that your proxies be returned promptly and that your shares are represented at the Annual Meeting. Whether or not you plan to attend the Annual Meeting, please complete, date, sign and promptly return the enclosed proxy card in the enclosed postagepre-paid envelope or vote your shares before the Annual Meeting by telephone or over the internet so your shares will be represented at the Annual Meeting.

The form of proxy card and this proxy statementProxy Statement have been approved by the Board of Directors and are being mailed and delivered to stockholders by its authority.

CONTACT INFORMATION FOR QUESTIONS AND ASSISTANCE WITH VOTING

If you have any questions or require any assistance with voting your shares, please contact:

Investor Relations

REGENXBIO Inc.

9712 Medical Center Drive,9600 Blackwell Road, Suite 100210

Rockville, MDMaryland 20850

or

Call Telephone:(240) 552-8181

If you need additional copies of this proxy statement or voting materials, you should contact Investor Relations as described above.

The Board A copy of Directors of REGENXBIO Inc.

Rockville, Maryland

April 18, 2016our Annual Report will be sent without charge to any stockholder who requests in writing, addressed to Investor Relations as described above. Our Annual Report may also be obtained via the internet at www.proxyvote.com.

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