REGENXBIO CFO has 4,902 shares withheld for tax

REGENXBIO’s CFO had shares withheld to cover taxes on vesting RSUs, and continues to hold over one hundred thousand shares directly.

Rhea-AI Filing Summary

REGENXBIO Inc. (RGNX) reported that Chief Financial Officer Mitchell Chan had 4,902 shares of common stock withheld on September 1, 2026 to pay tax liabilities arising from the vesting of restricted stock units originally granted on September 16, 2024. The shares were valued at $9.32 per share, based on the issuer’s closing price that day, and reflect a tax-withholding disposition rather than an open-market sale. Following this event, Chan directly holds 122,815 shares of REGENXBIO common stock. No Rule 10b5-1 trading plan is reported for this transaction.

Insider Trade Summary

Tax Withholding: 4,902 shares

Tax Withholding 1 txn

Insider Chan Mitchell

Role Chief Financial Officer

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock F1	4,902	$9.32	$46K

Holdings After Transaction: Common Stock — 122,815 shares (Direct)

Footnotes (1)

1. F1. Represents shares of common stock withheld to pay taxes upon the vesting of restricted stock units originally granted to the reporting person on September 16, 2024. The number of shares withheld was determined based on the closing price of the issuer's common stock on September 1, 2026.

Key Figures

Shares withheld for taxes: 4,902 shares Per-share valuation for tax withholding: $9.32 per share Shares held after transaction: 122,815 shares +1 more

4 metrics

Shares withheld for taxes 4,902 shares Common stock withheld on September 1, 2026 to pay tax liabilities from RSU vesting

Per-share valuation for tax withholding $9.32 per share Based on the closing price of REGENXBIO common stock on September 1, 2026

Shares held after transaction 122,815 shares Directly owned by CFO Mitchell Chan following the September 1, 2026 tax-withholding event

Original RSU grant date September 16, 2024 Restricted stock units whose vesting led to the September 1, 2026 tax withholding

Key Terms

restricted stock units, withheld to pay taxes, closing price

3 terms

restricted stock units financial

"upon the vesting of restricted stock units originally granted to the reporting person"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

withheld to pay taxes financial

"Represents shares of common stock withheld to pay taxes upon the vesting"

closing price financial

"determined based on the closing price of the issuer's common stock"

FAQ

What insider transaction did REGENXBIO Inc. (RGNX) disclose for its CFO?

REGENXBIO disclosed that CFO Mitchell Chan had 4,902 shares of common stock withheld on September 1, 2026 to pay taxes due upon the vesting of restricted stock units. This was a tax-withholding disposition, not an open-market purchase or sale.

At what price were the REGENXBIO (RGNX) shares valued for the CFO’s tax withholding?

The 4,902 shares withheld for CFO Mitchell Chan’s tax obligations were valued at $9.32 per share, which was the closing price of REGENXBIO’s common stock on September 1, 2026, as referenced in the filing footnote.

How many REGENXBIO (RGNX) shares does the CFO hold after this Form 4 transaction?

After the tax-withholding event on September 1, 2026, CFO Mitchell Chan directly holds 122,815 shares of REGENXBIO common stock. This figure reflects his direct ownership position following the disposition of shares to cover tax liabilities.

Was the REGENXBIO (RGNX) CFO’s transaction under a Rule 10b5-1 trading plan?

No. The filing indicates that the CFO’s 4,902-share tax-withholding disposition on September 1, 2026 was not made under a Rule 10b5-1 trading plan, and no such pre-arranged trading plan is reported for this transaction.

What triggered the REGENXBIO (RGNX) CFO’s tax-withholding share disposition?

The disposition was triggered by the vesting of restricted stock units originally granted to CFO Mitchell Chan on September 16, 2024. Shares of common stock were withheld on September 1, 2026 to satisfy tax obligations related to that vesting.

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Available on EDGAR 09/03/2026 - 05:51 PM Accepted by SEC EDGAR 09/03/2026 - 05:29 PM Learn about SEC filing dates

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).

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^*

Chan Mitchell

(Last) (First) (Middle)

C/O REGENXBIO INC.

9804 MEDICAL CENTER DRIVE

(Street)

ROCKVILLE MARYLAND 20850

(City) (State) (Zip)

UNITED STATES

(Country)

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

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/01/2026

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

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

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

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	09/01/2026		F		4,902(1)	D	$9.32	122,815	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. Represents shares of common stock withheld to pay taxes upon the vesting of restricted stock units originally granted to the reporting person on September 16, 2024. The number of shares withheld was determined based on the closing price of the issuer's common stock on September 1, 2026.

Remarks:

	/s/ Patrick J. Christmas as attorney-in-fact	09/03/2026
	** 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.
* Form 4: SEC 1474 (03-26)