REGENXBIO CEO reports ESPP buys, tax withholding

REGENXBIO Inc. Chief Executive Officer Simpson Curran reported routine equity compensation activity in company stock.

Rhea-AI Filing Summary

REGENXBIO Inc. Chief Executive Officer Simpson Curran reported routine equity compensation activity in company stock. On December 31, 2025, Curran acquired 951 shares of common stock at $6.9955 per share through the Employee Stock Purchase Plan (ESPP) for the July 1–December 31, 2025 purchase period, exempt under Rule 16b-3(c).

On June 30, 2026, Curran acquired an additional 1,453 shares at $10.18 per share via the ESPP for the January 1–June 30, 2026 purchase period. In line with the ESPP, these shares were bought at 85% of the relevant closing prices. On July 1, 2026, 6,818 shares were withheld at $13.09 per share to cover taxes upon vesting of restricted stock units granted on July 1, 2024, a non-market, tax-withholding disposition. After these transactions, Curran directly owned 338,053 shares of REGENXBIO common stock.

Insider Trade Summary

3 transactions reported

Mixed 3 txns

Insider Simpson Curran

Role Chief Executive Officer

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Common Stock	6,818	$13.09	$89K
Grant/Award	Common Stock	1,453	$10.18	$15K
Grant/Award	Common Stock	951	$6.9955	$7K

Holdings After Transaction: Common Stock — 338,053 shares (Direct)

Footnotes (5)

1. F1. The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the REGENXBIO Inc. Employee Stock Purchase Plan ("ESPP") for the ESPP purchase period of July 1, 2025 through December 31, 2025. This transaction is exempt under Rule 16b-3(c).
2. F2. In accordance with the ESPP, these shares were purchased based on 85% of the closing price of the Issuer's common stock on July 1, 2025.
3. F3. The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the ESPP for the ESPP purchase period of January 1, 2026 through June 30, 2026. This transaction is exempt under Rule 16b-3(c).
4. F4. In accordance with the ESPP, these shares were purchased based on 85% of the closing price of the Issuer's common stock on June 30, 2026.
5. F5. Represents shares of common stock withheld to pay taxes upon the vesting of restricted stock units originally granted to the reporting person on July 1, 2024. The number of shares withheld was determined based on the closing price of the issuer's common stock on July 1, 2026.

Key Figures

ESPP purchase 2025: 951 shares at $6.9955/share ESPP purchase 2026: 1,453 shares at $10.18/share Tax withholding shares: 6,818 shares at $13.09/share +3 more

6 metrics

ESPP purchase 2025 951 shares at $6.9955/share Common Stock acquired via ESPP on December 31, 2025

ESPP purchase 2026 1,453 shares at $10.18/share Common Stock acquired via ESPP on June 30, 2026

Tax withholding shares 6,818 shares at $13.09/share Shares withheld for RSU tax on July 1, 2026

Post-transaction holdings 338,053 shares Common Stock directly owned after July 1, 2026 transaction

ESPP discount basis 2025 85% of closing price ESPP purchase based on July 1, 2025 closing price

ESPP discount basis 2026 85% of closing price ESPP purchase based on June 30, 2026 closing price

Key Terms

Employee Stock Purchase Plan, ESPP, Rule 16b-3(c), restricted stock units, +1 more

5 terms

Employee Stock Purchase Plan financial

"acquisition of shares of the Issuer's common stock pursuant to the REGENXBIO Inc. Employee Stock Purchase Plan"

An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.

ESPP financial

"for the ESPP purchase period of July 1, 2025 through December 31, 2025"

An Employee Stock Purchase Plan (ESPP) is a company program that lets employees buy the company’s shares at a reduced price, usually by setting aside a small portion of their pay over time. It matters to investors because it encourages employees to own part of the business—like giving staff a discounted membership— which can boost commitment and performance, while also potentially increasing the number of shares available and affecting shareholder value.

Rule 16b-3(c) regulatory

"This transaction is exempt under Rule 16b-3(c)."

An SEC rule that lets corporate insiders avoid automatic "short‑swing" profit recovery when they buy or sell their company’s stock under a pre‑approved, written plan that meets specific conditions. For investors, it matters because it clarifies when insider trades are treated as routine, reducing legal uncertainty and helping distinguish trades made for ordinary compensation or pre‑planned reasons from those that might signal opportunistic or timely insider advantage.

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.

vesting financial

"to pay taxes upon the vesting of restricted stock units originally granted"

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

FAQ

What did REGENXBIO (RGNX) CEO Simpson Curran report in this Form 4?

Simpson Curran reported routine equity compensation activity, including ESPP share acquisitions and tax withholding. He acquired shares through the Employee Stock Purchase Plan and had shares withheld to cover taxes on vested restricted stock units, ending with 338,053 directly held common shares.

How many REGENXBIO (RGNX) shares were acquired by the CEO through the ESPP?

Curran acquired 951 shares on December 31, 2025 and 1,453 shares on June 30, 2026 via the Employee Stock Purchase Plan. These ESPP purchases were made at discounted prices based on 85% of the closing stock prices on July 1, 2025 and June 30, 2026.

What is the significance of the 6,818 REGENXBIO (RGNX) shares disposed in this filing?

The 6,818 shares were not market sales; they were withheld to pay taxes on restricted stock units vesting on July 1, 2026. This tax-withholding disposition is a standard administrative transaction and does not represent an open-market sale by the CEO.

At what prices did the REGENXBIO (RGNX) CEO’s ESPP transactions occur?

The ESPP acquisitions were reported at $6.9955 per share for 951 shares on December 31, 2025 and $10.18 per share for 1,453 shares on June 30, 2026. Both purchases followed plan terms using 85% of specified closing stock prices.

How many REGENXBIO (RGNX) shares does CEO Simpson Curran hold after these transactions?

Following the reported ESPP acquisitions and tax-withholding disposition, Simpson Curran directly holds 338,053 shares of REGENXBIO common stock. This total reflects his updated ownership position after the December 31, 2025, June 30, 2026, and July 1, 2026 equity-related transactions.

Are the REGENXBIO (RGNX) CEO’s reported transactions open-market buys or routine plan activity?

The reported transactions are routine plan-related activity, not open-market trading. Shares were acquired under the Employee Stock Purchase Plan and shares were withheld to satisfy tax obligations on vesting restricted stock units, all exempt under Rule 16b-3(c).

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Available on EDGAR 07/06/2026 - 04:52 PM Accepted by SEC EDGAR 07/06/2026 - 04:51 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^*

Simpson Curran

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
12/31/2025

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(1)	12/31/2025		A		951	A	$6.9955(2)	343,418	D
Common Stock(3)	06/30/2026		A		1,453	A	$10.18(4)	344,871	D
Common Stock	07/01/2026		F		6,818(5)	D	$13.09	338,053	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. The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the REGENXBIO Inc. Employee Stock Purchase Plan ("ESPP") for the ESPP purchase period of July 1, 2025 through December 31, 2025. This transaction is exempt under Rule 16b-3(c).

2. In accordance with the ESPP, these shares were purchased based on 85% of the closing price of the Issuer's common stock on July 1, 2025.

3. The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the ESPP for the ESPP purchase period of January 1, 2026 through June 30, 2026. This transaction is exempt under Rule 16b-3(c).

4. In accordance with the ESPP, these shares were purchased based on 85% of the closing price of the Issuer's common stock on June 30, 2026.

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

Remarks:

	/s/ Patrick J. Christmas as attorney-in-fact	07/06/2026
	** 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)