X0306 4 2016-06-13 0 0001590877 REGENXBIO Inc. RGNX 0001652824 Mills Kenneth T. C/O REGENXBIO INC. 9712 MEDICAL CENTER DRIVE, SUITE 100 ROCKVILLE MD 20850 1 1 0 0 President and CEO Common Stock 2016-06-13 4 M 0 125000 0.85 A 140440 D Employee Stock Option (Right to Buy) 0.85 2016-06-13 4 M 0 125000 0.00 D 2024-09-23 Common Stock 125000 583200 D 474,490 of the shares subject to the option shall be initial shares ("Initial Shares") and 233,710 of the shares subject to the option shall be contingent shares ("Contingent Shares"). 120,394 of the Initial Shares vested on September 17, 2014. Upon one year of continuous service to the Company after September 17, 2014, an additional 88,524 of the Initial Shares shall vest and an additional 7,377 of the Initial Shares shall vest upon each month of continuous service to the Company thereafter. 25% of the Contingent Shares were deemed vested as of September 17, 2014 on January 13, 2015 due to a subsequent event. The remainder of the Contingent Shares shall vest over four years of service following September 17, 2014, with 25% of the remaining 75% of Contingent Shares vesting upon one year of continuous service to the Company after September 17, 2014 and the remaining Contingent Shares vesting in 36 equal monthly installments thereafter. /s/ Kenneth T. Mills 2016-06-14