Mills Kenneth T. 4

4 · REGENXBIO Inc. · Filed Jan 29, 2026

AI-generated summary of this filing

Updated Jan 29, 2026

REGENXBIO (RGNX) Director Kenneth T. Mills Exercises Options

What Happened

Kenneth T. Mills, a director of REGENXBIO (RGNX), exercised options to acquire 225,000 shares on 2026-01-27. The exercise shows 225,000 shares acquired at $13.09 per share (value ≈ $2,945,250).
To satisfy the exercise price and tax withholding, 221,753 shares were withheld/disposed at an effective price of $13.41 per share (value ≈ $2,973,708). After withholding, Mills retained a net 3,247 shares (225,000 − 221,753). No open-market sale was involved.

Key Details

Transaction dates and amounts:
- 2026-01-27: Option exercise — 225,000 shares @ $13.09 (acquired), total ≈ $2,945,250.
- 2026-01-27: Tax/exercise withholding — 221,753 shares @ $13.41 (disposed), total ≈ $2,973,708.
- Filing date: 2026-01-29 (timely; Form 4 filed within the required window).
Shares owned after transaction: Not reported in the provided data; net shares retained from this exercise = 3,247.
Footnotes of note:
- The option was originally granted Jan 28, 2016, vested over time (25% on Jan 28, 2017, remainder monthly over 36 months) and was set to expire Jan 28, 2026.
- The 221,753-share disposition represents shares withheld to cover the exercise price and taxes; the number withheld was calculated using the closing price on Jan 27, 2026. No open-market sale occurred.
Transaction codes: M = option exercise/conversion; F = shares withheld for taxes/exercise price.

Context

This was effectively a cashless/net-share settlement of an option exercise: the reporting person exercised options and had most of the resulting shares withheld to cover costs and tax obligations, leaving a small net share increase (3,247 shares).
Such withholding transactions are common at option expiration and do not necessarily signal a buying or selling intent in the open market. They differ from open-market sales where shares are sold to third parties.

Form 4

Period: 2026-01-27

Director

Transactions

Exercise/Conversion
Common Stock
[F1]
2026-01-27$13.09/sh+225,000$2,945,250→ 707,871 total
Tax Payment
Common Stock
[F2]
2026-01-27$13.41/sh−221,753$2,973,708→ 486,118 total
Exercise/Conversion
Stock Options (Right to Buy)
[F1]
2026-01-27−225,000→ 225,000 total
Exercise: $13.09Exp: 2026-01-28→ Common Stock (225,000 underlying)

Footnotes (2)

[F1]The previously granted option, representing a right to purchase a total of 225,000 shares, became exercisable as follows: 25% of the shares subject to this option vested on January 28, 2017, and the balance vested in equal monthly installments over the 36 months thereafter.
[F2]Represents shares of common stock withheld to satisfy the exercise price and pay taxes upon the exercise of options originally granted to the reporting person on January 28, 2016, which were set to expire on January 28, 2026. The number of shares withheld was determined based on the closing price of the issuer's common stock on January 27, 2026. The transaction did not involve any open-market sale of securities.

Signature

/s/ Patrick J. Christmas as attorney-in-fact|2026-01-29

1 file