X0306 4 2021-01-12 false 0001590877 REGENXBIO Inc. RGNX 0001346164 Simpson Curran C/O REGENXBIO INC. 9600 BLACKWELL ROAD, SUITE 210 ROCKVILLE MD 20850 false true false false Chief Oper. & Tech. Officer Common Stock 2021-01-12 4 M false 1700.00 19.50 A 19448.00 D Common Stock 2021-01-12 4 S false 1700.00 50.03 D 17748.00 D Common Stock 2021-01-14 4 M false 1240.00 19.50 A 18988.00 D Common Stock 2021-01-14 4 M false 10372.00 35.80 A 29360.00 D Common Stock 2021-01-14 4 S false 11612.00 50.01 D 17748.00 D Stock Option (Right to Buy) 19.50 2021-01-12 4 M false 1700.00 0.00 D 2027-01-03 Common Stock 1700.00 1240.00 D Stock Option (Right to Buy) 19.50 2021-01-14 4 M false 1240.00 0.00 D 2027-01-03 Common Stock 1240.00 0.00 D Stock Option (Right to Buy) 35.80 2021-01-14 4 M false 10372.00 0.00 D 2028-01-03 Common Stock 10372.00 17128.00 D This transaction was effected pursuant to a Rule 10b5-1 trading plan. This transaction was executed in multiple trades at prices ranging from $50.00 to $50.10. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. The previously granted option, representing a right to purchase a total of 30,000 shares, became exercisable as follows: 25% of the shares subject to this option vested on January 4, 2018, and the balance vested in equal monthly installments over the 36 months thereafter. The previously granted option, representing a right to purchase a total of 55,000 shares, became exercisable as follows: 25% of the shares subject to this option vested on January 3, 2019, and the balance vests in equal monthly installments over the 36 months thereafter while the optionee provides continuous service to the Issuer. /s/ Patrick J. Christmas as attorney-in-fact 2021-01-14