X0508 4 2026-01-27 false 0001590877 REGENXBIO Inc. RGNX 0001652824 Mills Kenneth T. C/O REGENXBIO INC. 9804 MEDICAL CENTER DRIVE ROCKVILLE MD 20850 true false false false false Common Stock 2026-01-27 4 M false 225000.00 13.09 A 707871.00 D Common Stock 2026-01-27 4 F false 221753.00 13.41 D 486118.00 D Stock Options (Right to Buy) 13.09 2026-01-27 4 M false 225000.00 0.00 D 2026-01-28 Common Stock 225000.00 225000.00 D The previously granted option, representing a right to purchase a total of 225,000 shares, became exercisable as follows: 25% of the shares subject to this option vested on January 28, 2017, and the balance vested in equal monthly installments over the 36 months thereafter. Represents shares of common stock withheld to satisfy the exercise price and pay taxes upon the exercise of options originally granted to the reporting person on January 28, 2016, which were set to expire on January 28, 2026. The number of shares withheld was determined based on the closing price of the issuer's common stock on January 27, 2026. The transaction did not involve any open-market sale of securities. /s/ Patrick J. Christmas as attorney-in-fact 2026-01-29