REGENXBIO Inc. — Director's Dealing 2017

May 3, 2017

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: REGENXBIO Inc. (RGNX)
CIK: 0001590877
Period of Report: 2017-05-01

Reporting Person: HAYDEN DONALD J JR (Director)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2017-05-01	Common Stock	M	20000	$0.85	Acquired	48599	Direct
2017-05-01	Common Stock	S	4738	$21.34	Disposed	43861	Direct
2017-05-01	Common Stock	S	25262	$22.43	Disposed	18599	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2017-05-01	Stock Option (Right to Buy)	$0.85	M	20000	Disposed	2024-09-23	Common Stock (20000)	Direct

Footnotes

F1: This transaction was effected pursuant to a Rule 10b5-1 trading plan.

F2: This transaction was executed in multiple trades at prices ranging from $21.00 to $21.90. 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.

F3: This transaction was executed in multiple trades at prices ranging from $22.00 to $22.925. 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.

F4: The option, representing a right to purchase a total of 354,100 shares, became exercisable as follows: 237,269 of the shares subject to the option are initial shares ("Initial Shares") and 116,831 of the shares subject to the option are contingent shares ("Contingent Shares"). 60,197 of the Initial Shares vested on September 17, 2014, 44,268 of the Initial Shares vested on September 17, 2015 and an additional 3,689 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 vest over four years of service following September 17, 2014, with 25% of the remaining 75% of Contingent Shares having vested on September 17, 2015 and the remaining Contingent Shares vesting in 36 equal monthly installments thereafter.