X0306 4 2020-07-27 0 0001590877 REGENXBIO Inc. RGNX 0001652936 Fox Allan M. C/O REGENXBIO INC. 9600 BLACKWELL ROAD, SUITE 210 ROCKVILLE MD 20850 1 0 0 0 Common Stock 2020-07-27 5 G 0 E 225000 0.00 D 1414110 I By The Allan M. Fox Revocable Trust Common Stock 2020-07-27 5 G 0 E 225000 0.00 A 225000 I By The Harriette B. Fox Revocable Trust Common Stock 2020-08-06 5 G 0 E 90000 0.00 D 1324110 I By The Allan M. Fox Revocable Trust Common Stock 2020-08-06 5 G 0 E 90000 0.00 A 315000 I By The Harriette B. Fox Revocable Trust Common Stock 278541 I By grantor retained annuity trust Common Stock 315000 I By AMF Gift Trust LLC Common Stock 722485 I By AMF Family Gift Trust LLC Common Stock 1412542 I By DING LLC At the time of the transaction, the reporting person was a trustee of The Allan M. Fox Revocable Trust, which was the direct beneficial owner of the shares of the Issuer's common stock. The reporting person disclaims beneficial ownership of such shares. Such shares are now held by DING LLC. This transaction involved a gift of shares of common stock held by The Allan M. Fox Revocable Trust to The Harriette B. Fox Revocable Trust, a revocable trust established for the benefit of the reporting person's spouse. The shares subsequently were transferred to HBF Gift Trust LLC on August 6, 2020. The reporting person disclaims beneficial ownership of such shares except to the extent of his indirect pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose. The shares are held by DUNE, a grantor retained annuity trust established by The Allan M. Fox Revocable Trust. The reporting person serves as the trustee of DUNE. The reporting person disclaims beneficial ownership of such shares except to the extent of his indirect pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose. /s/ Patrick J. Christmas as attorney-in-fact 2020-09-18