# EDGAR Filing Document

**Accession Number:** 0001785173
**File Stem:** 0000902664-25-004684
**Filing Date:** 2025-10
**Character Count:** 12642
**Document Hash:** c582c7bb6a9128f9235b09611df2d7d9
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000902664-25-004684.hdr.sgml**: 20251031

**ACCESSION NUMBER**: 0000902664-25-004684

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20251031

**DATE AS OF CHANGE**: 20251031

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** 89bio, Inc.
- **CENTRAL INDEX KEY:** 0001785173
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 831114349
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-91200
- **FILM NUMBER:** 251438653

**BUSINESS ADDRESS:**
- **STREET 1:** 655 MONTGOMERY STREET
- **STREET 2:** SUITE 1500
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94111
- **BUSINESS PHONE:** (415) 432-9270

**MAIL ADDRESS:**
- **STREET 1:** 655 MONTGOMERY STREET
- **STREET 2:** SUITE 1500
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94111
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Adage Capital Management, L.P.
- **CENTRAL INDEX KEY:** 0001535978

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET, 52ND FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 617-867-2800

**MAIL ADDRESS:**
- **STREET 1:** 200 CLARENDON STREET, 52ND FLOOR
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116

## Ex-99

**<u>Schedule A</u>**

This Schedule sets forth information with respect to each purchase and sale of shares of Common Stock which were effectuated by the Reporting Persons since filing of the Schedule 13D. All transactions were effectuated in the open market through a broker. The price reported in the column Price Per Share ($) is a weighted average price if a price range is indicated in the column Price Range ($). These shares of Common Stock were purchased or sold in multiple transactions at prices between the price ranges below. The Reporting Persons will undertake to provide to the staff of the SEC, upon request, full information regarding the number of shares of Common Stock purchased or sold at each separate price.

---

| | | | | |
|:---|:---|:---|:---|:---|
| &nbsp;&nbsp;<u>Trade Date</u> | &nbsp;&nbsp;<u>Shares Purchased (Sold)</u> | &nbsp;&nbsp;<u>Price Per Share ($)\*</u> | &nbsp;&nbsp;<u>Price Per Share ($)\*</u> | &nbsp;&nbsp;<u>Price Range ($)\*</u> |
| &nbsp;&nbsp;10/27/2025 | &nbsp;&nbsp;90268 | &nbsp;&nbsp;90268 | &nbsp;&nbsp;14.8150 |  |
| &nbsp;&nbsp;10/27/2025 | &nbsp;&nbsp;537861 | &nbsp;&nbsp;537861 | &nbsp;&nbsp;14.8190 | &nbsp;&nbsp;14.8125-14.8200 |
| &nbsp;&nbsp;10/28/2025 | &nbsp;&nbsp;470874 | &nbsp;&nbsp;470874 | &nbsp;&nbsp;14.8300 |  |
| &nbsp;&nbsp;10/28/2025 | &nbsp;&nbsp;194184 | &nbsp;&nbsp;194184 | &nbsp;&nbsp;14.8200 |  |
| &nbsp;&nbsp;10/29/2025 | &nbsp;&nbsp;1815977 | &nbsp;&nbsp;1815977 | &nbsp;&nbsp;14.8400 |  |
| &nbsp;&nbsp;10/29/2025 | &nbsp;&nbsp;890836 | &nbsp;&nbsp;890836 | &nbsp;&nbsp;14.8285 | &nbsp;&nbsp;14.8250-14.8300 |

---

\*Excluding commissions.

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 1)**

**89bio, Inc.**

*(Name of Issuer)*

**Common Stock, par value $0.001 per share**

*(Title of Class of Securities)*

**282559103**

*(CUSIP Number)*

**Robert Atchinson**<br>Adage Capital Partners GP, L.L.C.<br>200 Clarendon Street, 52nd Floor<br>Boston MA 02116<br>617-867-2800

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**10/29/2025**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **282559103** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Adage Capital Management, L.P.** | Name of reporting person<br>**Adage Capital Management, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0%** | Percent of class represented by amount in Row (11)<br>**0%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IA** | Type of Reporting Person (See Instructions)<br>**IA** | |

---

| **CUSIP No.** | **282559103** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Robert Atchinson** | Name of reporting person<br>**Robert Atchinson** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0%** | Percent of class represented by amount in Row (11)<br>**0%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

| **CUSIP No.** | **282559103** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Phillip Gross** | Name of reporting person<br>**Phillip Gross** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0%** | Percent of class represented by amount in Row (11)<br>**0%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, par value $0.001 per share

**(b) Name of Issuer:**
89bio, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
655 MONTGOMERY STREET, SUITE 1500, SAN FRANCISCO, CA, 94111

This Amendment No. 1 ("Amendment No. 1") amends the statement on Schedule 13D filed with the Securities and Exchange Commission (the "SEC") on October 3, 2025 (the "Schedule 13D") relates to the shares of common stock, par value $0.001 per share (the "Common Stock"), of 89bio, Inc., a Delaware corporation (the "Issuer"). This Amendment No. 1 amends and restates Item 5 as set forth below. Capitalized terms used herein and not otherwise defined in this Amendment No. 1 have the meanings set forth in the Schedule 13D. This Amendment No. 1 is the final amendment to the Schedule 13D and constitutes an "exit filing" for the Reporting Persons.

**Item 5. Interest in Securities of the Issuer**

**(a)**
See rows (11) and (13) of the cover pages to this Schedule 13D for the aggregate number of shares of Common Stock and percentages of the shares of Common Stock beneficially owned by each of the Reporting Persons.

**(b)**
See rows (7) through (10) of the cover pages to this Schedule 13D for the number of shares of Common Stock as to which each Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition.

**(c)**
The transactions in the shares of Common Stock since the filing of the Schedule 13D by the Reporting Persons, which were all in the open market, are set forth in Schedule A, and are incorporated herein by reference. In addition, on October 29, 2025, the Reporting Persons tendered all of their 13,097,587 shares of Common Stock into the tender offer pursuant to the Merger Agreement at an offer price of (i) $14.50 per share in cash, and (ii) one non-tradeable contingent value right per share, all as described in the Company's SEC filings.

### SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Adage Capital Management, L.P.

**Signature:** /s/ Robert Atchinson

**Name/Title:** By: Adage Capital Partners LLC, its General Partner, By: Robert Atchinson, its Managing Member

**Date:** 10/31/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Robert Atchinson

**Signature:** /s/ Robert Atchinson

**Name/Title:** Robert Atchinson, Individually

**Date:** 10/31/2025

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

**Reporting Person:** Phillip Gross

**Signature:** /s/ Phillip Gross

**Name/Title:** Phillip Gross, Individually

**Date:** 10/31/2025