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

Rhea-AI Filing Summary

89bio (ETNB) disclosed an insider transaction tied to its acquisition by Roche. Director Michael R. Hayden reported the disposition of common stock and stock options on 10/30/2025 in connection with the deal’s closing mechanics.

Shares were tendered/converted for $14.50 per share in cash plus one non‑tradeable CVR worth up to $6.00 per share upon specified milestones. Reported holdings included 80,904 shares (direct), 103,978 shares (indirect via Genworks 2 Consulting Inc., controlled by the reporting person’s spouse), and 61,538 shares (indirect via The Hayden Family Trust, controlled by the reporting person’s spouse). The filing shows 0 shares beneficially owned after the transaction.

Outstanding stock options became fully vested immediately prior to the merger and were cancelled for cash equal to any in‑the‑money value plus one CVR per underlying share. Options with exercise prices at or above $14.50 and below $20.50 received CVRs only, while options with exercise prices at or above $20.50 were cancelled without consideration.

Insights

M&A and Equity Compensation Analyst

Form 4 records merger-related share and option cancellation terms.

The transaction reflects standard post‑closing mechanics: common shares were exchanged for cash plus a contingent value right tied to future milestones. The director’s positions moved to zero as equity was tendered or cancelled pursuant to the merger agreement.

Equity awards were treated per the contract. In‑the‑money options received cash for intrinsic value plus a CVR per underlying share. Options at or above $14.50 and below $20.50 received CVRs only, and those at or above $20.50 were cancelled with no consideration.

Future value depends on whether CVR milestones are achieved under the CVR Agreement; the filing lists no schedule of milestones. Subsequent filings may provide additional details on any CVR payments.

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

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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^*

Hayden Michael R

(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)

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

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		U		80,904(1)(2)	D	(1)(2)	0	D
Common Stock	10/30/2025		U		103,978(1)(2)	D	(1)(2)	0	I	See footnote(3)
Common Stock	10/30/2025		U		61,538(1)(2)	D	(1)(2)	0	I	See footnote(4)

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			27,647	(5)(6)(7)	11/09/2028	Common Stock	27,647	$0	0	D
Stock Option (Right to Buy)	$1.93	10/30/2025		D			2,933	(5)(6)(7)	01/30/2029	Common Stock	2,933	$0	0	D
Stock Option (Right to Buy)	$3.11	10/30/2025		D			22,730	(5)(6)(7)	07/30/2029	Common Stock	22,730	$0	0	D
Stock Option (Right to Buy)	$21.4	10/30/2025		D			7,000	(5)(6)(7)	04/05/2030	Common Stock	7,000	$0	0	D
Stock Option (Right to Buy)	$24.29	10/30/2025		D			7,000	(5)(6)(7)	06/22/2030	Common Stock	7,000	$0	0	D
Stock Option (Right to Buy)	$24.16	10/30/2025		D			12,500	(5)(6)(7)	04/15/2031	Common Stock	12,500	$0	0	D
Stock Option (Right to Buy)	$2.64	10/30/2025		D			25,000	(5)(6)(7)	05/16/2032	Common Stock	25,000	$0	0	D
Stock Option (Right to Buy)	$14.7	10/30/2025		D			27,400	(5)(6)(7)	02/09/2033	Common Stock	27,400	$0	0	D
Stock Option (Right to Buy)	$9.98	10/30/2025		D			45,150	(5)(6)(7)	02/01/2034	Common Stock	45,150	$0	0	D
Stock Option (Right to Buy)	$9.6	10/30/2025		D			56,400	(5)(6)(7)	02/01/2035	Common Stock	56,400	$0	0	D

Explanation of Responses:

1. 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, [continues to Footnote 2]

2. [continues from Footnote 1] in cash, without interest less any required withholding taxes, upon the achievement of specified milestones on or prior to the applicable milestone outside dates, 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.

3. These shares are held directly by Genworks 2 Consulting Inc., over which the Reporting Person's wife has sole voting and investment power.

4. These shares are held directly by The Hayden Family Trust, over which the Reporting Person's wife has sole voting and investment power.

5. 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 6]

6. [Continues from Footnote 5] 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 7]

7. [Continues from Footnote 6] 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 Michael R. Hayden	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) report in this Form 4?

A director reported disposal of shares and options on 10/30/2025 due to the Roche acquisition terms.

What consideration did ETNB shareholders receive?

Each share received $14.50 in cash plus one non‑tradeable CVR worth up to $6.00 per share upon milestones.

How were the director’s ETNB holdings impacted?

Reported holdings went to 0 shares after tender/merger settlement.

How were ETNB stock options treated in the merger?

They vested and were cancelled for cash equal to intrinsic value plus one CVR per underlying share if in‑the‑money.

What happened to out‑of‑the‑money ETNB options?

Options with exercise prices at or above $14.50 and below $20.50 received CVRs only; at or above $20.50 received no consideration.

Who controlled the indirect ETNB holdings?

Genworks 2 Consulting Inc. and The Hayden Family Trust were controlled by the reporting person’s spouse.