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

Company: REGENXBIO Inc.
Filing Date: 2025-11-26
Form: S-3
Chunk 3
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 PROSPECTUS                             |     |  1 |
| WHERE YOU CAN FIND MORE INFORMATION               |     |  2 |
| THE COMPANY                                       |     |  3 |
| RISK FACTORS                                      |     |  3 |
| USE OF PROCEEDS                                   |     |  3 |
| DESCRIPTION OF CAPITAL STOCK                      |     |  4 |
| DESCRIPTION OF WARRANTS                           |     | 11 |
| DESCRIPTION OF DEBT SECURITIES                    |     | 14 |
| DESCRIPTION OF RIGHTS                             |     | 22 |
| DESCRIPTION OF UNITS                              |     | 24 |
| PLAN OF DISTRIBUTION                              |     | 25 |
| LEGAL MATTERS                                     |     | 29 |
| EXPERTS                                           |     | 29 |

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS This prospectus, each prospectus supplement and the information incorporated by reference in this prospectus and each prospectus supplement contain “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), which are subject to the safe harbor created by those sections for such statements. These statements express a belief, expectation or intention and are generally accompanied by words that convey projected future events or outcomes such as “anticipate,” “assume,” “believe,” “continue,” “could,” “design,” “estimate,” “expect,” “forecast,” “goal,” “intend,” “may,” “objective,” “plan,” “position,” “potential,” “predict,” “project,” “seek,” “should,” “will,” “would” or variations of such words or by similar expressions. We have based these forward-looking statements on our current expectations, estimates and assumptions and analyses in light of our experience and our perception of historical trends, current conditions and expected future developments, as well as other factors we believe are appropriate under the circumstances. However, whether actual results and developments will conform with our expectations and predictions is subject to a number of risks, uncertainties, assumptions and other important factors, including, but not limited to:

| • |     | our ability to establish and maintain development partnerships, including our collaboration with AbbVie Inc. to                  
 develop and commercialize ABBV-RGX-314 and our collaboration with Nippon Shinyaku Co., Ltd. to develop and