REGENXBIO Inc. 10-Q

Item 5. Other Information. Rule 10b5-1 Trading Plans The adoption or termination of contracts, instructions or written plans for the purchase or sale of our securities by our Section 16 officers and directors for the three months ended March 31, 2025, each of which is intended to satisfy the affirmative defense of Rule 10b5-1(c) (Rule 10b5-1 Plan), were as follows: Rule 10b5-1 Trading Plan Aggregate # of Provides for Securities to be Name Title Action Date Adopted Expiration Date Purchase/Sale Purchased/Sold Curran Simpson President and Chief Executive Officer Adoption 3/28/2025 3/1/2026 Sale 36,169 Other than as described above, during the three months ended March 31, 2025, none of our directors or Section 16 reporting officers adopted or terminated any Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement (as such terms are defined in Item 408 of the SEC's Regulation S-K). 40 Table of Contents Item 6. E xhibits. Incorporated by Reference Exhibit Number Description Form Exhibit Number Filing Date Filed or Furnished Herewith 3.1 Restated Certificate of Incorporation 8-K 3.1 6/7/21 3.2 Amended and Restated Bylaws 8-K 3.2 9/22/15 10.1† Collaboration and License Agreement dated January 14, 2025 between the Registrant and Nippon Shinyaku Co., Ltd. X 31.1 Certification of the Chief Executive Officer as required by Section 302 of the Sarbanes-Oxley Act of 2002 X 31.2 Certification of the Chief Financial Officer as required by Section 302 of the Sarbanes-Oxley Act of 2002 X 32.1 Certifications of the Chief Executive Officer and Chief Financial Officer as required by 18 U.S.C. 1350 X 101 The following materials from the Company’s Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2025 formatted in Inline XBRL (eXtensible Business Reporting Language): (i) Consolidated Balance Sheets (ii) Consolidated Statements of Operations and Comprehensive Income (Loss) (iii) Consolidated Statements of Stockholders’ Equity (iv) Consolidated Statements of Cash Flows (v) Notes to Consolidated Financial Statements X 104 The cover page from the Company’s Quarterly Report on Form 10-Q for the fiscal quarter ended March 31, 2025 formatted in Inline XBRL (included in Exhibit 101) † Portions of this exhibit have been omitted. The certification attached as Exhibit 32.1 that accompanies this Quarterly Report on Form 10-Q is not deemed filed with the SEC and is not to be incorporated by reference into any filing of REGENXBIO Inc. under the Securities Act or the Exchange Act, whether made before or after the date of this Quarterly Report on Form 10-Q, irrespective of any general incorporation language contained in such filing. 41 Table of Contents SIGNA TURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. REGENXBIO Inc. Dated: May 12, 2025 /s/ Curran Simpson Curran Simpson President and Chief Executive Officer (Principal Executive Officer) Dated: May 12, 2025 /s/ Mitchell Chan Mitchell Chan Chief Financial Officer (Principal Financial Officer and Principal Accounting Officer) 42