[Form 4] REGENXBIO Inc. Insider Trading Activity

Rhea-AI Filing Summary

Simpson Curran, who is listed as both Chief Executive Officer and a Director of REGENXBIO Inc. (RGNX), reported an open-market sale of company common stock under a pre-existing trading plan. On 10/09/2025 the reporting person disposed of 20,811 shares at a weighted average price of $12.62 per share, with the filing noting the sale was effected pursuant to a Rule 10b5-1 trading plan and executed in multiple trades at prices ranging from $12.50 to $12.84.

Following this reported transaction the reporting person beneficially owned 216,162 shares. The Form 4 was signed via attorney-in-fact on 10/10/2025.

Positive

• Transaction executed under a Rule 10b5-1 plan, indicating pre-arranged compliance steps
• Filing discloses weighted average price range and affirms willingness to provide trade details upon request
• Reporting person retains material ownership with 216,162 shares beneficially owned after the sale

Negative

• Reported disposal of 20,811 shares reduced the reporting person's direct holdings
• Sale reported via Form 4, which may attract investor attention to insider liquidity

Insights

Corporate Governance Analyst

Insider sale under a 10b5-1 plan reduces reported holdings but follows an approved trading defense.

This sale of 20,811 shares at a weighted average of $12.62 was executed under a Rule 10b5-1 plan, which provides an affirmative defense to insider trading claims when properly established and operated. The filing explicitly states the trades occurred in multiple executions between $12.50 and $12.84.

The remaining beneficial ownership of 216,162 shares is disclosed, and the Form 4 was submitted by an attorney-in-fact on 10/10/2025. Monitor subsequent Form 4 filings for additional plan activity or changes in beneficial ownership over the next several reporting periods.

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).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

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)
10/09/2025

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	10/09/2025		S(1)		20,811	D	$12.62(2)	216,162	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 $12.50 to $12.84. 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	10/10/2025
	** 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 the REGENXBIO (RGNX) insider sell on 10/09/2025?

The reporting person sold 20,811 shares of common stock on 10/09/2025.

At what price were the RGNX shares sold by the insider?

The sale was executed in multiple trades at prices ranging from $12.50 to $12.84, with a weighted average of $12.62.

Was the insider sale part of a pre-arranged plan?

Yes, the Form 4 states the transaction was effected pursuant to a Rule 10b5-1 trading plan.

How many RGNX shares does the reporting person own after the sale?

The reporting person beneficially owned 216,162 shares following the reported transaction.

Who filed the Form 4 for the insider transaction?

The Form 4 bears a signature by Patrick J. Christmas acting as attorney-in-fact, dated 10/10/2025.