X0306 4 2015-09-16 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 5208 0.00 A 2025-09-16 Common Stock 5208 5208 D 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 2015-09-16