FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * Fox Allan M.   2. Issuer Name and Ticker or Trading Symbol REGENXBIO Inc. [RGNX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O REGENXBIO INC., 9712 MEDICAL CENTER DRIVE, SUITE 100 3. Date of Earliest Transaction (Month/Day/Year) 09/22/2015 (Street) ROCKVILLE, MD 20850 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 09/22/2015   C   722,485 A (1) 722,485 I See Footnote (2) Common Stock 09/22/2015   C   722,485 A (1) 722,485 I See Footnote (3) Common Stock 09/22/2015   C   853,915 A (1) 1,576,400 I See Footnote (3) Common Stock 09/22/2015   C   478,463 A (1) 2,054,863 I See Footnote (3) Common Stock               443,700 I See Footnote (4)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Series A Preferred Stock

(1)

09/22/2015

C

722,485

(1)

(1)

Common Stock

722,485

$ 0

0

I

See Footnote (2)

Series A Preferred Stock

(1)

09/22/2015

C

722,485

(1)

(1)

Common Stock

722,485

$ 0

0

I

See Footnote (3)

Series B Preferred Stock

(1)

09/22/2015

C

853,915

(1)

(1)

Common Stock

853,915

$ 0

0

I

See Footnote (3)

Series C Preferred Stock

(1)

09/22/2015

C

478,463

(1)

(1)

Common Stock

478,463

$ 0

0

I

See Footnote (3)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Fox Allan M. C/O REGENXBIO INC. 9712 MEDICAL CENTER DRIVE, SUITE 100 ROCKVILLE, MD 20850	X	X

Signatures

/s/ Allan M. Fox		09/22/2015
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Each share of Preferred Series A, Preferred Series B, and Preferred Series C Stock is convertible and will automatically convert on a 1:1 basis into the Issuer's common stock upon the closing of the Issuer's initial public offering of common stock pursuant to an effective registration statement filed with the U.S. Securities and Exchange Commission. These shares have no expiration date.
(2)	The Reporting Person is a trustee of The Allan M. Fox Trust (U/A/D April 21, 2015), the direct beneficial owner of the shares. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise or such portion of the shares of common stock of the Issuer held by The Allan M. Fox Trust (U/A/D April 21, 2015), in which the Reporting Person has no pecuniary interest.
(3)	The Reporting Person is a trustee of The Allan M. Fox Revocable Trust, the direct beneficial owner of the shares. The Reporting Person disclaims beneficial ownership within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended, or otherwise or such portion of the shares of common stock of the Issuer held by The Allan M. Fox Revocable Trust, in which the Reporting Person has no pecuniary interest.
(4)	The Reporting Person holds shared dispositive power over the shares held by FoxKiser Holdings, LLC with John Daniel Kiser, with the Reporting Person having a 60% voting interest in FoxKiser Holdings, LLC.

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