Generation Bio Co. — Director's Dealing 2026

Feb 9, 2026

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: Generation Bio Co. (GBIO)
CIK: 0001733294
Period of Report: 2026-02-09

Reporting Person: JONAS JEFFREY M (Director)

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2026-02-09	Stock Option (right to buy)	$3.874	D	3000	Disposed		Common Stock (3000)	Direct
2026-02-09	Stock Option (right to buy)	$45.924	D	4246	Disposed		Common Stock (4246)	Direct
2026-02-09	Stock Option (right to buy)	$190.00	D	5200	Disposed		Common Stock (5200)	Direct
2026-02-09	Stock Option (right to buy)	$265.90	D	1500	Disposed		Common Stock (1500)	Direct
2026-02-09	Stock Option (right to buy)	$61.90	D	1920	Disposed		Common Stock (1920)	Direct
2026-02-09	Stock Option (right to buy)	$48.30	D	2500	Disposed		Common Stock (2500)	Direct
2026-02-09	Stock Option (right to buy)	$33.20	D	6000	Disposed		Common Stock (6000)	Direct

Footnotes

F1: Pursuant to the terms of that certain Agreement and Plan of Merger (the "Merger Agreement"), by and among Generation Bio. Co. (the "Issuer"), XOMA Royalty Corporation ("Parent") and Parent's wholly-owned subsidiary, XRA 7 Corp. ("Merger Sub"), dated as of December 15, 2025, Merger Sub merged with and into the Issuer, effective as of February 9, 2026 (the "Effective Time"), with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent.

F2: Pursuant to the terms of the Merger Agreement, effective as of immediately prior to the Effective Time, each option to purchase shares of common stock, par value $0.0001 per share, of the Issuer (the "Common Stock") that was outstanding and unexercised as of immediately prior to the Effective Time and had an exercise price per share that was less than $4.2913 (the "Cash Amount") (each such option, an "In-The-Money Option"), became fully vested and was automatically cancelled and converted into the right to receive an amount in cash, without interest, equal to the product obtained by multiplying (x) the excess of the Cash Amount over the exercise price per share of Common Stock underlying such In-the-Money Option at the Effective Time by (y) the number of shares of Common Stock underlying such In-the-Money Option at the Effective Time.

F3: Pursuant to the terms of the Merger Agreement, effective as of immediately prior to the Effective Time, each option to purchase shares of Common Stock that was outstanding and unexercised as of immediately prior to the Effective Time and had an exercise price per share that was equal to or greater than the Cash Amount was automatically cancelled for no consideration.