X0306 4/A 2015-09-16 2015-09-17 0 0001590877 REGENXBIO Inc. RGNX 0001192128 BESHAR LUKE M C/O REGENXBIO INC. 9712 MEDICAL CENTER DRIVE, SUITE 100 ROCKVILLE MD 20850 1 0 0 0 Stock Option (Right to Buy) 22.00 2015-09-16 4 A 0 9375 0.00 A 2025-09-16 Common Stock 9375 9375 D The Number of Derivative Securities Acquired, the Amount of Underlying Securities and the Number of Derivative Securities Beneficially Owned Following Reported Transaction were inadvertently misreported by the Reporting Person on the Form 4 file on September 17, 2015. The option will vest in equal monthly installments over the 12 months following September 16, 2015, with immediate full vesting in the event of a change in control. /s/ Luke M. Beshar 2015-09-22