XOMA closes Generation Bio (GBIO) acquisition with $4.2913 cash plus CVR

Rhea-AI Filing Summary

Generation Bio Co. became a wholly owned subsidiary of XOMA Royalty Corporation after a merger completed on February 9, 2026. Under the merger agreement, each tendered Generation Bio common share was exchanged for $4.2913 in cash per share plus one non-tradeable contingent value right (CVR) per share.

Each CVR represents the right to receive potential future cash payments, with an estimated maximum contingent consideration of $25.01 per CVR, subject to specified terms and conditions. In connection with this transaction, Atlas Venture–affiliated funds that were 10% owners reported disposition of 711,193, 116,693 and 60 Generation Bio common shares, and reported owning zero shares afterward.

Insights

M&A and equity ownership analyst

Generation Bio is taken private via cash-and-CVR merger.

The filing shows completion of a merger in which XOMA Royalty Corporation acquired Generation Bio, which now operates as XOMA’s wholly owned subsidiary. Consideration per Generation Bio share consisted of $4.2913 in cash plus one contingent value right (CVR).

The CVR provides potential additional cash payments up to an estimated maximum of $25.01 per CVR, contingent on conditions in a CVR agreement. Atlas Venture–affiliated 10% holders reported tendering a combined 10%-plus stake, ending with zero reported common shares as of the February 9, 2026 effective time.

The transaction effectively removes Generation Bio from the public equity markets and converts prior equity stakes into a mix of immediate cash and contingent, performance-dependent value. Future disclosures from the acquirer or in CVR-related materials would govern any actual CVR payouts.

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

X

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^*

Atlas Venture Fund X, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Generation Bio Co. [ GBIO ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
02/09/2026

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

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

	Form filed by One Reporting Person
X	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	02/09/2026		U(1)(2)		711,193	D	(1)(2)	0	D(3)
Common Stock	02/09/2026		U(1)(2)		116,693	D	(1)(2)	0	I	See footnote(4)
Common Stock	02/09/2026		U(1)(2)		60	D	(1)(2)	0	I	See footnote(5)

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

1. Name and Address of Reporting Person^*

Atlas Venture Fund X, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

ATLAS VENTURE ASSOCIATES X, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Atlas Venture Associates X, LLC

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Atlas Venture Opportunity Fund I, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Atlas Venture Associates Opportunity I, L.P.

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

1. Name and Address of Reporting Person^*

Atlas Venture Associates Opportunity I, LLC

(Last) (First) (Middle)

300 TECHNOLOGY SQUARE, 8TH FLOOR

(Street)

CAMBRIDGE MA 02139

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

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

Explanation of Responses:

1. 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, the shares (the "Shares") of common stock, par value $0.0001 per share, of the Issuer (the "Common Stock") that were tendered to Merger Sub prior to the expiration time of the offer were exchanged for (i) a purchase price of $4.2913 per Share to the stockholders in cash, without interest and less any applicable tax withholding (the "Cash Amount"), plus (ii) one non-tradeable contingent value right per Share (the "CVR"),

2. (continued from footnote 1) which represents the right to receive certain contingent payments in cash in accordance with the terms and subject to the conditions of a contingent value rights agreement entered into by Parent and the rights agent, with an estimated maximum contingent consideration amount of $25.01 per CVR (the Cash Amount plus one CVR, collectively, the "Offer Price"). After completion of the tender offer, pursuant to the terms of the Merger Agreement, 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.

3. The shares are held directly by Atlas Venture Fund X, L.P. ("Atlas Venture Fund X"). The general partner of Atlas Venture Fund X is Atlas Venture Associates X, L.P. ("AVA X LP"). Atlas Venture Associates X, LLC ("AVA X LLC") is the general partner of AVA X LP. Each of AVA X LP and AVA X LLC disclaims Section 16 beneficial ownership of the securities held by Atlas Venture Fund X, except to the extent of its pecuniary interest therein, if any.

4. The shares are held directly by Atlas Venture Opportunity Fund I, L.P. ("Atlas Venture Opportunity Fund I"). The general partner of Atlas Venture Opportunity Fund I is Atlas Venture Associates Opportunity I, LP ("AVAO I LP"). Atlas Venture Associates Opportunity I, LLC ("AVAO I LLC") is the general partner of AVAO I LP. Each of AVAO I LP and AVAO I LLC disclaims Section 16 beneficial ownership of the securities held by Atlas Venture Opportunity Fund I, except to the extent of its pecuniary interest therein, if any.

5. The shares are held directly by AVAO I LP. AVAO I LLC is the general partner of AVAO I LP. AVAO I LLC disclaims Section 16 beneficial ownership of the securities held by AVAO I LP except to the extent of its pecuniary interest therein, if any.

	Atlas Venture Fund X, L.P., By: Atlas Venture Associates X, L.P., Its: General Partner, By: Atlas Venture Associates X, LLC, Its: General Partner, By: /s/ Ommer Chohan, Chief Financial Officer	02/09/2026
	Atlas Venture Associates X, L.P., By: Atlas Venture Associates X, LLC, Its: General Partner, By: /s/ Ommer Chohan, Chief Financial Officer	02/09/2026
	Atlas Venture Associates X, LLC, By: /s/ Ommer Chohan, Chief Financial Officer	02/09/2026
	Atlas Venture Opportunity Fund I, L.P., By: Atlas Venture Associates Opportunity I, L.P., Its general partner, By: Atlas Venture Associates Opportunity I, LLC, Its general partner, By: /s/ Ommer Chohan, Chief Financial Officer	02/09/2026
	Atlas Venture Associates Opportunity I, L.P., By: Atlas Venture Associates Opportunity I, LLC, Its general partner, By: /s/ Ommer Chohan, Chief Financial Officer	02/09/2026
	Atlas Venture Associates Opportunity I, LLC, By: /s/ Ommer Chohan, Chief Financial Officer	02/09/2026
	** 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.

FAQ

What did the XOMA merger pay Generation Bio (GBIO) shareholders per share?

Generation Bio shareholders received $4.2913 in cash per share plus one non-tradeable contingent value right (CVR) per share. The CVR offers potential additional cash payments under specified conditions, with an estimated maximum contingent consideration of $25.01 per CVR.

What happened to Generation Bio (GBIO) in the XOMA Royalty Corporation deal?

Generation Bio was merged into a subsidiary of XOMA Royalty Corporation, becoming XOMA’s wholly owned subsidiary. The merger followed a tender offer in which shares were exchanged for cash plus CVRs, and was effective on February 9, 2026, removing Generation Bio from standalone public ownership.

How were Atlas Venture’s Generation Bio (GBIO) shares treated in the merger?

Atlas Venture–affiliated funds reported that their Generation Bio common shares were exchanged in the merger. They disclosed dispositions of 711,193, 116,693 and 60 shares, and reported zero shares beneficially owned afterward, reflecting full participation in the cash-and-CVR merger consideration.

What is the contingent value right (CVR) in the Generation Bio (GBIO) merger?

Each Generation Bio share received one non-tradeable CVR alongside cash. The CVR represents a contractual right to certain contingent cash payments, subject to terms and conditions in a CVR agreement, with an estimated maximum contingent consideration of $25.01 per CVR.

When did the Generation Bio (GBIO) merger with XOMA become effective?

The merger became effective on February 9, 2026, when Merger Sub was combined with Generation Bio. From that effective time, Generation Bio continued as the surviving corporation and a wholly owned subsidiary of XOMA Royalty Corporation, with prior common shares converted into cash and CVRs.

Are Generation Bio (GBIO) shareholders still common stockholders after the merger?

After the merger’s February 9, 2026 effective time, prior Generation Bio common shares were exchanged for cash plus CVRs. The reporting Atlas Venture funds showed zero shares beneficially owned, indicating that former holders became claimants to cash and CVR rights rather than continuing common stockholders.