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
Adage Capital Partners GP, L.L.C., 200 Clarendon Street, 52nd Floor
Boston, MA, 02116
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)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. Checkbox not checked

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP No.

282559103

Name of reporting person

Adage Capital Management, L.P.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

Aggregate amount beneficially owned by each reporting person

0.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

0 %

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP No.

282559103

Name of reporting person

Robert Atchinson

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

Aggregate amount beneficially owned by each reporting person

0.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

0 %

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

CUSIP No.

282559103

Name of reporting person

Phillip Gross

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 0.00

Aggregate amount beneficially owned by each reporting person

0.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

0 %

Type of Reporting Person (See Instructions)

IN, HC

SCHEDULE 13D

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, CALIFORNIA , 94111.

Item 1 Comment:

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.

(d)

Not applicable.

(e)

October 29, 2025

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.

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

Robert Atchinson

Signature:	/s/ Robert Atchinson
Name/Title:	Robert Atchinson, Individually
Date:	10/31/2025

Phillip Gross

Signature:	/s/ Phillip Gross
Name/Title:	Phillip Gross, Individually
Date:	10/31/2025

Amendment: SEC Form SCHEDULE 13D/A filed by 89bio Inc.