Company: RGNX
Filing Date: 2025-06-13
Form Type: S-3
Source: 0001193125-25-140870
Chunk: 16

Company: REGENXBIO Inc.
Filing Date: 2025-06-13
Form: S-3
Chunk 16
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 Exchange Act, that are in place at the time of an offering pursuant to this prospectus that provides for periodic sales of their securities on the basis of parameters described in such trading 
 plans;                                                                                                                                                                                                            |

| • |     | through firm-commitment underwritten public offerings; |

| • |     | a combination of any such methods of sale; or |

| • |     | any other method permitted pursuant to applicable law. |

The Selling Stockholder may, from time to time, pledge or grant a security interest in some or all of the Shares owned by it and, if it defaults in the performance of its secured obligations, the pledgees or secured parties may offer and sell the Shares from time to time under this prospectus or under an amendment or supplement to this prospectus to include the pledgee, transferee, or other successors in interest as the Selling Stockholder under this prospectus. The Selling Stockholder also may transfer the Shares in other circumstances, in which case the transferees, pledgees or other successors in interest will be the beneficial owners for purposes of this prospectus. 11

In connection with the sale of Shares, the Selling Stockholder may enter into hedging
transactions with broker-dealers or affiliates thereof or other financial institutions, which may in turn engage in short sales of our common stock in the course of hedging the positions it assumes. The Selling Stockholder may also sell shares of
common stock short and deliver the Shares to close out its short positions, or loan or pledge the Shares to broker-dealers that in turn may sell these securities. The Selling Stockholder may also enter into option or other transactions with
broker-dealers or affiliates thereof or other financial institutions or the creation of one or more derivative securities which require the delivery to such broker-dealer or affiliates thereof or other financial institution of Shares offered by this
prospectus, which Shares such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

In addition, the Selling Stockholder may enter into derivative or hedging transactions with third parties, or sell securities not covered by
this prospectus to third parties in privately negotiated transactions. In connection with such a transaction, the third parties may sell the applicable securities covered by and pursuant to this prospectus or any pricing supplement, as the case may
be. If so, the third party may use securities borrowed from the Selling Stockholder or others to settle such sales and may use securities received from the Selling Stockholder to close