Company: RGNX
Filing Date: 2025-06-13
Form Type: S-3
Source: 0001193125-25-140870
Chunk: 11

Company: REGENXBIO Inc.
Filing Date: 2025-06-13
Form: S-3
Chunk 11
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 in the issuance or transfer by the corporation of any stock of the corporation to 
 the interested stockholder, subject to limited exceptions;                                                     |

| • |     | any transaction involving the corporation that has the effect of increasing the proportionate share of the stock 
 of any class or series of the corporation beneficially owned by the interested stockholder; or                   |

| • |     | the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other 
 financial benefits provided by or through the corporation.                                                    |

An “interested stockholder” is a person who, together with affiliates and associates, owns or within the immediately preceding three years did own 15% or more of the corporation’s voting stock. Undesignated Preferred Stock The ability of our board of directors, without action by the stockholders, to issue up to 10,000,000 shares of undesignated preferred stock with voting or other rights or preferences as designated by our board of directors 6

could impede the success of any attempt to change control of us. The existence of authorized but unissued shares of preferred stock may have the effect of deferring hostile takeovers or delaying
changes in control or management of our company.

Stockholder Action by Written Consent; Stockholder Meetings

Our restated certificate of incorporation and amended and restated bylaws eliminate the right of stockholders to act by written consent without
a meeting. As a result, a holder controlling a majority of our capital stock would not be able to amend our bylaws or remove directors without holding a meeting of our stockholders called in accordance with our amended and restated bylaws. Our
restated certificate of incorporation and amended and restated bylaws provide that a special meeting of stockholders may be called only by our chairman of the board or our chief executive officer (or if there is no chief executive officer, the
president), or by a resolution adopted by a majority of our board of directors. These provisions might delay the ability of our stockholders to force consideration of a proposal or for stockholders controlling a majority of our capital stock to take
any action, including the removal of directors.

Requirements for Advance Notification of Stockholder Nominations and Proposals

Our amended and restated bylaws establish advance notice procedures with respect to stockholder proposals to be brought before a stockholder
meeting and the nomination of candidates for election as directors, other than nominations made by or at the direction of the board of directors or a committee of the board of directors