Company: RGNX
Filing Date: 2025-11-26
Form Type: S-3
Source: 0001193125-25-300539
Chunk: 12

Company: REGENXBIO Inc.
Filing Date: 2025-11-26
Form: S-3
Chunk 12
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 sinking fund provisions; |

| • |     | the amount that shares of such series shall be entitled to receive in the event of our liquidation, dissolution 
 or winding-up;                                                                                                  |

| • |     | the terms and conditions, if any, on which shares of such series shall be convertible or exchangeable for shares 
 of our stock of any other class or classes, or other series of the same class;                                   |

5

| • |     | the voting rights, if any, of shares of such series in addition to those set forth under the caption entitled, 
 “Voting Rights” below;                                                                                         |

| • |     | the status as to reissuance or sale of shares of such series redeemed, purchased or otherwise reacquired, or 
 surrendered to us on conversion or exchange;                                                                 |

| • |     | the conditions and restrictions, if any, on the payment of dividends or on the making of other distributions on,                                                                                                                                          
 or the purchase, redemption or other acquisition by us, of our common stock or of any other class of our stock ranking junior to the shares of such series as to dividends or upon liquidation (including, but not limited to, at such times as there are 
 arrearages in the payment of dividends or sinking fund installments);                                                                                                                                                                                     |

| • |     | the conditions and restrictions, if any, on the creation of indebtedness, or on the issue of any additional stock 
 ranking on a parity with or prior to the shares of such series as to dividends or upon liquidation; and           |

| • |     | any other rights, preferences, privileges, limitations and restrictions of such preferred stock. |

If we issue shares of preferred stock under this prospectus and any related prospectus supplement, the shares will be fully paid and non-assessableand will not have, or be subject to, any preemptive or similar rights. Voting Rights The Delaware General Corporation Law provides that the holders of shares of preferred stock will have the right to vote separately as a class on any proposal involving fundamental changes in the rights of holders of that preferred stock. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation. Transfer Agent and Registrar The transfer agent and registrar for any series of preferred stock will be set forth in the applicable prospectus supplement. Effects on Common Stock Our issuance of preferred stock could decrease the amount of earnings and assets available for distribution to the holders of common stock or could adversely affect the rights and powers