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

Rhea-AI Filing Summary

89bio, Inc. (ETNB) director Edward Morrow Atkinson III reported derivative transactions tied to the company’s change of control. On October 30, 2025, following Roche Holdings, Inc.’s tender offer and subsequent merger, multiple stock option grants were disposed of or cancelled pursuant to the merger terms.

Holders of options with an exercise price below the $14.50 per share cash consideration became entitled to cash equal to the in‑the‑money amount plus one non‑tradeable contingent value right (CVR) per underlying share. Each CVR provides potential contingent payments of up to an aggregate $6.00 per share, payable upon specified milestones under the CVR Agreement. Options with exercise prices equal to or above $14.50 but less than $20.50 were eligible to receive CVRs (and potential milestone payments as defined), while options at or above $20.50 were cancelled without payment.

Reported grants included options with exercise prices of $4.44, $14.70, $9.98, and $9.60, each showing 0 derivative securities beneficially owned following the transactions, held directly.

Insights

M&A and securities counsel

Director’s options settled under Roche–89bio merger terms; Form 4 is administrative.

The filing reflects option treatment triggered by the closing of Roche’s tender offer and the subsequent merger. The core mechanics: cash of $14.50 per share plus one CVR per share, with CVRs allowing up to an additional $6.00 per share upon milestone achievements under the CVR Agreement.

Option outcomes are formulaic. In-the-money options receive cash equal to the excess over $14.50 per share plus CVRs. Options with strikes at or above $14.50 but below $20.50 receive CVRs and contingent cash per the stated formula. Options at or above $20.50 are cancelled without consideration.

This is a post‑closing settlement disclosure rather than a new financing event. It lists methods and amounts defined by the merger agreement; actual CVR value depends on milestone attainment, which this excerpt does not specify.

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

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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^*

Atkinson Edward Morrow III

(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

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)	$4.44	10/30/2025		D			20,000	(1)(2)(3)(4)(5)	02/17/2032	Common Stock	20,000	$0	0	D
Stock Option (Right to Buy)	$14.7	10/30/2025		D			27,400	(1)(2)(3)(4)(5)	02/09/2033	Common Stock	27,400	$0	0	D
Stock Option (Right to Buy)	$9.98	10/30/2025		D			45,150	(1)(2)(3)(4)(5)	02/01/2034	Common Stock	45,150	$0	0	D
Stock Option (Right to Buy)	$9.6	10/30/2025		D			56,400	(1)(2)(3)(4)(5)	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"). 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").

3. 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 4]

4. [Continues from Footnote 3] 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 5]

5. [Continues from Footnote 4] 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 Edward Morrow Atkinson III	10/30/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What did 89bio (ETNB) disclose about insider equity on October 30, 2025?

A director reported option dispositions/cancellations pursuant to Roche’s tender offer and the closing merger terms.

What was the per-share cash consideration for 89bio (ETNB) common stock?

The cash consideration was $14.50 per share, plus one non-tradeable CVR per share.

How much could the CVR for 89bio (ETNB) be worth?

Each CVR represents potential contingent payments of up to an aggregate $6.00 per share, subject to milestones.

How were in-the-money options treated in the 89bio (ETNB) merger?

They became vested and were cancelled for cash equal to the amount above $14.50 per share, plus one CVR per underlying share.

What happened to options with exercise prices between $14.50 and $20.50?

They were converted to the right to receive a CVR and contingent cash as milestones are met, per the stated formula.

What happened to options at or above $20.50 exercise price?

They were cancelled immediately prior to the effective time without any cash or CVR.

Did the reporting person hold derivative securities after the transactions?

Each reported option grant shows 0 derivative securities beneficially owned following the transactions.