[Form 4] 89bio, Inc. Insider Trading Activity

Rhea-AI Filing Summary

89bio (ETNB) insider transaction tied to merger completion. On 10/30/2025, Chief Medical Officer Harry H. Mansbach reported transactions associated with the Roche acquisition. He disposed of 352,656 shares of common stock in exchange for $14.50 per share in cash plus one non-tradeable CVR representing contingent payments of up to $6.00 per share, as provided by the merger terms.

Immediately prior to the effective time of the merger, 50,000 common shares were acquired at $0 upon settlement of performance-based RSUs. All listed stock options were canceled pursuant to the agreement: in-the-money options were converted into the right to receive cash equal to the excess of the $14.50 closing amount over the exercise price per underlying share plus one CVR; out-of-the-money options received CVRs only; options with exercise prices at or above $20.50 were canceled without consideration. Following the reported transactions, beneficial ownership showed 0 common shares and 0 derivative securities.

Insights

Corporate actions analyst

Insider’s holdings cashed out or canceled per merger; CVR adds contingent value.

The filing reflects the mechanical outcomes of the Roche acquisition of 89bio. The CMO’s 352,656 shares were exchanged at $14.50 per share plus one CVR worth up to $6.00 per share, consistent with the offer structure at the merger’s effective time on 10/30/2025. RSUs settled into 50,000 shares at $0 immediately prior to closing.

Stock options were treated per clearly defined thresholds: in-the-money options converted to cash equal to the spread versus $14.50 plus a CVR; out-of-the-money options received CVRs only; options with exercise prices at or above $20.50 were canceled without consideration. Actual cash realizations depend on exercise prices and any future CVR milestone achievements.

Because this is an administrative insider report of a completed merger consideration, the investment thesis impact is neutral. Any incremental value hinges on CVR milestones under the CVR Agreement.

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
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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^*

Mansbach Harry H

(Last) (First) (Middle)

C/O 89BIO, INC.

655 MONTGOMERY STREET, SUITE 1500

(Street)

SAN FRANCISCO CA 94111

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
89bio, Inc. [ ETNB ]

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

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

3. Date of Earliest Transaction (Month/Day/Year)
10/30/2025

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

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

X	Form filed by One Reporting Person
	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	10/30/2025		A		50,000(1)	A	$0	352,656	D
Common Stock	10/30/2025		U		352,656(2)(3)	D	(2)(3)	0	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
Stock Option (Right to Buy)	$1.93	10/30/2025		D			98,204	(4)(5)(6)	01/10/2029	Common Stock	98,204	$0	0	D
Stock Option (Right to Buy)	$3.11	10/30/2025		D			39,037	(4)(5)(6)	07/30/2029	Common Stock	39,037	$0	0	D
Stock Option (Right to Buy)	$32.5	10/30/2025		D			45,000	(4)(5)(6)	02/14/2030	Common Stock	45,000	$0	0	D
Stock Option (Right to Buy)	$23.01	10/30/2025		D			67,500	(4)(5)(6)	02/05/2031	Common Stock	67,500	$0	0	D
Stock Option (Right to Buy)	$4.44	10/30/2025		D			70,000	(4)(5)(6)	02/16/2032	Common Stock	70,000	$0	0	D
Stock Option (Right to Buy)	$14.7	10/30/2025		D			120,000	(4)(5)(6)	02/09/2033	Common Stock	120,000	$0	0	D
Stock Option (Right to Buy)	$9.98	10/30/2025		D			195,000	(4)(5)(6)	02/01/2034	Common Stock	195,000	$0	0	D
Stock Option (Right to Buy)	$9.6	10/30/2025		D			320,000	(4)(5)(6)	02/01/2035	Common Stock	320,000	$0	0	D

Explanation of Responses:

1. Represents settlement by the Issuer of performance-based restricted stock units granted to the Reporting Person under the Company's Amended and Restated 2019 Equity Incentive Plan on September 9, 2022 and February 1, 2024, which vested as of immediately prior to and conditioned upon the occurrence of the effective time of the Merger (as defined below), pursuant to the Merger Agreement (as defined below).

2. Disposed of pursuant to the Agreement and Plan of Merger (the "Merger Agreement"), dated as of September 17, 2025, by and among 89bio, Inc. (the "Issuer"), Roche Holdings, Inc. ("Parent") and Bluefin Merger Subsidiary, Inc., a wholly owned subsidiary of Parent ("Merger Sub"). On October 30, 2025, Parent and Merger Sub completed a tender offer pursuant to the terms of the Merger Agreement for all outstanding shares of common stock of the Issuer (each, a "Share") for an offer price of (i) $14.50 per Share in cash, without interest (the "Closing Amount") less any required withholding taxes, plus (ii) one non-tradeable contingent value right (each, a "CVR") representing the right to receive certain contingent payments of up to an aggregate amount of $6.00 per Share, in cash, without interest less any required withholding taxes, upon the achievement of specified milestones on or prior to the applicable milestone outside dates, [continues to Footnote 3]

3. [continues from Footnote 2] subject to and in accordance with the terms of the Contingent Value Rights Agreement (the "CVR Agreement") (the Closing Amount plus one CVR, collectively, the "Offer Price"). Merger Sub thereafter merged with and into the Issuer, with the Issuer continuing as the surviving corporation and a wholly owned subsidiary of Parent (the "Merger"). At the effective time of the Merger, each issued and outstanding Share (other than any Excluded Shares (as such term is defined in the Merger Agreement)) was cancelled in exchange for the right to receive the Offer Price. In addition, as of immediately prior to and conditioned upon the occurrence of the effective time of the Merger, pursuant to the Merger Agreement, each outstanding restricted stock unit or performance-based restricted stock unit became fully vested and was cancelled in exchange for the right to receive the Offer Price.

4. As of immediately prior to and conditioned upon the occurrence of the effective time of the Merger, pursuant to the Merger Agreement, each outstanding option to purchase Shares (each, an "Option") became fully vested and exercisable, and to the extent not exercised prior to the effective time of the Merger, was cancelled and converted into the right to receive (i) an amount in cash (without interest and subject to deduction for any required withholding taxes) equal to the product of (A) an amount equal to the excess of the Closing Amount over the exercise price per Share with respect to such Option and (B) the number of Shares subject to such Option plus (ii) one CVR with respect to each Share subject to such Option (the "Option Consideration"); provided, however, that if the exercise price per Share of any Option was equal to or greater than the Closing Amount, but less than $20.50 (any such option, an "Out of the Money Option"), [continues to Footnote 5]

5. [Continues from Footnote 4] such Out of the Money Option was not entitled to any payment of the Closing Amount in respect thereof and each Out of the Money Option was converted into the right to receive the CVR included in the Option Consideration with respect to each Share underlying such Out of the Money Option and became entitled to receive, at each time a milestone payment becomes due and payable under the terms of the CVR Agreement, an amount in cash equal to the product of (i) the number of Shares subject to such Out of the Money Option, and (ii) the amount, if any, by which (A) the Closing Amount plus the applicable milestone payment plus any other milestone payment that previously became due and payable under the terms of the CVR Agreement exceeds (B) the exercise price per Share with respect to such Out of the Money Option plus the amounts, [continues to Footnote 6]

6. [Continues from Footnote 5] if any, paid to such Option holder with respect to such CVR in respect of any milestone payments that previously became due and payable under the terms of the CVR Agreement; provided further, that any Option with an exercise price that was equal to or greater than $20.50, was cancelled immediately prior to the effective time of the Merger without the receipt of any payment of the Closing Amount or CVR in respect thereof.

	/s/ Ryan A. Murr, as attorney-in-fact for Harry H. Mansbach	10/30/2025
	** 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.
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FAQ

What did 89bio (ETNB) disclose in this Form 4?

The CMO reported merger-related transactions on 10/30/2025, including the exchange of 352,656 shares at $14.50 per share plus one CVR and the settlement of 50,000 RSUs.

What was the offer price for ETNB shares in the merger?

Each share was exchanged for $14.50 in cash plus one non-tradeable CVR representing contingent payments of up to $6.00 per share.

How many ETNB shares did the CMO tender or dispose of?

352,656 common shares were disposed of in the merger exchange on 10/30/2025.

What happened to the CMO’s RSUs?

50,000 performance-based RSUs vested immediately prior to the effective time and settled into common shares at $0.

How were ETNB stock options treated in the merger?

In-the-money options convert to cash equal to $14.50 minus the exercise price per share plus one CVR; out-of-the-money options receive CVRs only; options at or above $20.50 are canceled with no consideration.

What is the CMO’s post-transaction holding in ETNB?

The filing reports 0 common shares and 0 derivative securities beneficially owned following the transactions.

Who acquired 89bio and when did the exchange occur?

Roche (via a subsidiary) completed the tender offer and merger, with transactions reported on 10/30/2025 under the merger agreement.