[Form 4] REGENXBIO Inc. Insider Trading Activity

Rhea-AI Filing Summary

Simpson Curran, serving as Chief Executive Officer and a director of REGENXBIO Inc. (RGNX), reported a sale of 7,624 shares of the issuer's common stock on 09/29/2025. The sale was effected under a Rule 10b5-1 trading plan and executed in multiple trades at prices ranging from $10.00 to $10.08, with a weighted average sale price of $10.03. Following the reported transaction, the reporting person beneficially owned 236,973 shares, held directly. The Form 4 was signed by an attorney-in-fact, Patrick J. Christmas, on 10/01/2025. No derivative transactions or other securities classes were reported in this filing.

Positive

• Transaction executed under a Rule 10b5-1 plan, indicating the sale was pre-planned and reducing concerns about opportunistic insider timing.
• Clear Section 16 disclosure with weighted average sale price and post-transaction beneficial ownership reported, supporting market transparency.

Negative

• Reduction in direct holdings by 7,624 shares on 09/29/2025, leaving 236,973 shares owned; the sale modestly decreases insider ownership.

Insights

Securities Analyst

TL;DR: Routine insider sale under a pre-established 10b5-1 plan; disclosed and appears compliant with Section 16 reporting.

The sale of 7,624 shares reported by Simpson Curran was executed under a Rule 10b5-1 plan, which typically indicates a pre-planned disposition rather than opportunistic trading. The weighted average price of $10.03 across trades at $10.00–$10.08 is clearly disclosed, and the filing shows direct beneficial ownership of 236,973 shares after the sale. From an investor perspective, this is a transparent, routine disclosure that preserves market transparency but does not on its own indicate change in company fundamentals.

Corporate Governance Expert

TL;DR: Disclosure aligns with governance best practices; trade executed via 10b5-1 and formally reported on Form 4.

The filing documents a timely Form 4 reporting and cites a 10b5-1 trading plan, reducing compliance concerns about selective insider trading. The reporting person remains a significant direct holder with 236,973 shares post-transaction. The involvement of an attorney-in-fact for signature is a common administrative practice and does not alter the substantive disclosure. This transaction appears routine and properly documented under Section 16 requirements.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person^*

Simpson Curran

(Last) (First) (Middle)

C/O REGENXBIO INC.

9804 MEDICAL CENTER DRIVE

(Street)

ROCKVILLE MD 20850

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
REGENXBIO Inc. [ RGNX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
09/29/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/29/2025		S(1)		7,624	D	$10.03(2)	236,973	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. This transaction was effected pursuant to a Rule 10b5-1 trading plan.

2. This transaction was executed in multiple trades at prices ranging from $10.00 to $10.08. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

Remarks:

	/s/ Patrick J. Christmas as attorney-in-fact	10/01/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did Simpson Curran (RGNX) report on the Form 4?

The Form 4 reports a sale of 7,624 shares of REGENXBIO common stock on 09/29/2025 and a post-transaction direct beneficial ownership of 236,973 shares.

Was the insider sale by Simpson Curran part of a 10b5-1 plan?

Yes. The filing explicitly states the transaction was effected pursuant to a Rule 10b5-1 trading plan.

At what price were the shares sold in the reported transaction?

The sale was executed in multiple trades at prices ranging from $10.00 to $10.08, with a weighted average sale price of $10.03.

How was the Form 4 signed and when?

The Form 4 was signed by an attorney-in-fact, Patrick J. Christmas, on 10/01/2025.

Does the filing report any derivative securities transactions?

No. The filing contains no reported derivative transactions; only a non-derivative sale of common stock is disclosed.