X0508 4 2025-05-30 false 0001590877 REGENXBIO Inc. RGNX 0001652936 Fox Allan M. C/O REGENXBIO INC. 9804 MEDICAL CENTER DRIVE ROCKVILLE MD 20850 true false false false false Common Stock 2025-05-30 4 A false 7768.00 0.00 A 19054.00 D Common Stock 722485.00 I By AMF Family Gift Trust LLC Common Stock 315000.00 I By AMF Gift Trust LLC Common Stock 315000.00 I By HBF Gift Trust LLC Common Stock 1529981.00 I By Quaker Gray LLC Stock Options (Right to Buy) 8.85 2025-05-30 4 A false 39815.00 0.00 A 2035-05-30 Common Stock 39815.00 39815.00 D Represents shares of common stock underlying a time-based restricted stock unit award (RSU). 100% of the shares subject to this RSU will vest on May 1, 2026 subject to the continuous service of the recipient to the Issuer. 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 option will vest in 12 equal monthly installments following May 30, 2025 subject to the continuous service of the optionee to the Issuer. /s/ Patrick J. Christmas as attorney-in-fact 2025-06-03