REGENXBIO Inc. Stock Compensation Disclosure

11. Stock-based Compensation

In September 2014, the Board of Directors adopted the 2014 Stock Plan (the 2014 Plan). In June 2015, the Board of Directors adopted the 2015 Equity Incentive Plan (the 2015 Plan), which became effective upon the Company’s initial public offering in September 2015. The 2015 Plan replaced the 2014 Plan, and as of the effective date of the 2015 Plan, no further awards may be issued under the 2014 Plan. Any options or awards outstanding under the 2014 Plan as of the effective date of the 2015 Plan remained outstanding and effective. The number of authorized shares under the 2015 Plan automatically increases annually on the first business day of each fiscal year, by the lesser of (i) 4% of the total number of shares of common stock outstanding on December 31 of the prior year, or (ii) a number of common shares determined by the Board of Directors. As of December 31, 2024, the total number of shares of common stock authorized for issuance under the 2015 Plan and the 2014 Plan was 19,118,989, of which 1,512,367 remained available for future grants under the 2015 Plan. An additional 1,981,975 shares were authorized for issuance under the 2015 Plan effective in January 2025.

The 2014 Plan and 2015 Plan provide for the issuance of stock options, stock appreciation rights, restricted and unrestricted stock and unit awards, and performance cash awards to employees, members of the Board of Directors and consultants of the Company. Since the inception of the plans, the Company has issued only stock options and restricted stock units under the plans. Stock options under the 2014 Plan and 2015 Plan generally expire 10 years following the date of grant. Options typically vest over a four-year period, but vesting provisions can vary by award based on the discretion of the Board of Directors. Certain stock option

awards granted by the Company may include performance conditions that must be achieved in order for vesting to occur. Stock options under the 2014 Plan and 2015 Plan have an exercise price at least equal to the estimated fair value of the Company’s common stock on the date of grant. Restricted stock units typically vest over a four-year period, but vesting provisions can vary by award based on the discretion of the Board of Directors. Upon vesting, restricted stock units are settled in common stock of the Company.

Shares of common stock underlying awards previously issued under the 2014 Plan and 2015 Plan which are reacquired by the Company, withheld by the Company in payment of the purchase price, exercise price or withholding taxes, expired, cancelled due to forfeiture or otherwise terminated other than by exercise or settlement, are added to the number of shares of common stock available for issuance under the 2015 Plan. Shares available for issuance under the 2015 Plan may be either authorized but unissued shares of the Company’s common stock or common stock reacquired by the Company and held in treasury. The 2015 Plan expires in June 2025, 10 years from the date it was adopted by the Board of Directors, unless earlier terminated.

Stock-based Compensation Expense

As of December 31, 2024, the Company had $59.7 million of unrecognized stock-based compensation expense related to stock options, restricted stock units and the 2015 Employee Stock Purchase Plan (the 2015 ESPP), which is expected to be recognized over a weighted-average period of 2.3 years.

Stock Options

The weighted-average grant date fair value per share of options granted during the years ended December 31, 2024, 2023 and 2022 was $9.98, $13.66 and $19.43, respectively. During the years ended December 31, 2024, 2023 and 2022, the total number of stock options exercised was 290,753, 222,935 and 331,912, respectively, resulting in total proceeds of $1.5 million, $1.5 million and $2.8 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2024, 2023 and 2022 was $3.1 million, $2.9 million and $6.9 million, respectively.

Restricted Stock Units

The total intrinsic value of restricted stock units vested during the years ended December 31, 2024, 2023 and 2022 was $6.7 million, $3.9 million and $2.2 million, respectively.

Employee Stock Purchase Plan

In June 2015, the Board of Directors adopted the 2015 ESPP, which became effective upon the Company’s initial public offering in September 2015. The number of authorized shares reserved for issuance under the 2015 ESPP automatically increases on the first business day of each fiscal year by the lesser of (i) 1% of the shares of common stock outstanding on the last business day of the prior fiscal year; or (ii) the number of shares determined by the Board of Directors. Unless otherwise determined by the administrator of the 2015 ESPP, two offering periods of six months’ duration will begin each year on January 1 and July 1. As of December 31, 2024, the total number of shares of common stock authorized for issuance under the 2015 ESPP was 1,426,994, of which 912,964 remained available for future issuance. During the years ended December 31, 2024, 2023 and 2022, 105,400, 103,388 and 75,733 shares of common stock, respectively, were issued under the 2015 ESPP.