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

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 10)*

89bio, Inc.

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

282559103

(CUSIP Number)

RA Capital Management, L.P.

200 Berkeley Street, 18^th Floor

Boston, MA 02116

Attn: Peter Kolchinsky

Telephone: 617.778.2500

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

August 5, 2024

(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. ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Section 240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

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, as amended (“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).

Item 1 of the Statement is amended and supplemented as follows:

This Amendment No. 10 (this “Amendment No. 10” or this “13D/A”) amends and supplements the Schedule 13D originally filed with the Securities and Exchange Commission (the “SEC”) on November 13, 2019, and amended on July 10, 2020, September 21, 2020, June 2, 2021, July 6, 2022, October 21, 2022, March 30, 2023, August 11, 2023, December 13, 2023 and March 6, 2024 (as amended, the “Statement”), filed by RA Capital Management, L.P., Dr. Kolchinsky, Mr. Shah, and RA Capital Healthcare Fund, L.P. with respect to the common stock, par value $0.001 per share (the “Common Stock”), of 89bio, Inc., a Delaware corporation (the “Issuer”). Unless otherwise defined herein, capitalized terms used in this Amendment No. 10 shall have the meanings ascribed to them in the Statement. Unless amended or supplemented below, the information in the Statement remains unchanged.

Item 2 of the Statement is amended and restated in its entirety to read as follows:

The Reporting Persons’ ownership of the Issuer’s securities includes (i) 13,840,034 shares of Common Stock held directly by the Fund; (ii) 335,364 shares of Common Stock held directly by RA Capital Nexus Fund, L.P. (the “Nexus Fund”); (iii) a total of 78,900 vested stock options (right to buy) held by Derek DiRocco for the benefit of RA Capital; and (iv) a total of 1,081,081 pre-funded warrants (“PFWs”), through which the Fund has the right to acquire 1,081,081 shares of Common Stock subject to the PFW Beneficial Ownership Blocker as defined below. The PFWs contain a provision (the “PFW Beneficial Ownership Blocker”) which precludes exercise of the PFWs to the extent that, following the exercise, the Reporting Persons, together with their affiliates and other attribution parties, would beneficially own more than 9.99% of the Issuer’s outstanding Common Stock. By virtue of the PFW Beneficial Ownership Blocker, the PFWs are currently not exercisable.

RA Capital Healthcare Fund GP, LLC is the general partner of the Fund and RA Capital Nexus Fund GP, LLC is the general partner of the Nexus Fund. The general partner of RA Capital is RA Capital Management GP, LLC, of which Dr. Kolchinsky and Mr. Shah are the controlling persons. RA Capital serves as investment adviser for the Fund and the Nexus Fund and may be deemed a beneficial owner, for purposes of Section 13(d) of the Act, of any securities of the Issuer held by the Fund or the Nexus Fund. The Fund and the Nexus Fund have delegated to RA Capital the sole power to vote and the sole power to dispose of all securities held in the Fund’s and the Nexus Fund’s portfolio, including the shares of the Issuer’s Common Stock reported herein. Because the Fund and the Nexus Fund have divested themselves of voting and investment power over the reported securities they hold and may not revoke that delegation on less than 61 days’ notice, the Fund and the Nexus Fund disclaim beneficial ownership of the securities they hold for purposes of Section 13(d) of the Act and therefore disclaim any obligation to report ownership of the reported securities under Section 13(d) of the Act. As managers of RA Capital, Dr. Kolchinsky and Mr. Shah may be deemed beneficial owners, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned by RA Capital. RA Capital, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of the securities reported in this 13D/A other than for the purpose of determining their obligations under Section 13(d) of the Act, and the filing of this 13D/A shall not be deemed an admission that either RA Capital, Dr. Kolchinsky, or Mr. Shah is the beneficial owner of such securities for any other purpose.

Item 5 of the Statement is hereby amended and restated in its entirety to read as follows:

Item 7 of the Statement is amended and supplemented by the following:

SIGNATURES

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.

Dated: August 7, 2024

Exhibit 1

JOINT FILING AGREEMENT

This Joint Filing Agreement, dated as of August 7, 2024, is by and among RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. (the foregoing are collectively referred to herein as the “Filers”).

Each of the Filers may be required to file with the United States Securities and Exchange Commission a statement on Schedule 13G and/or 13D with respect to Common Stock, par value $0.001 per share of 89bio, Inc. beneficially owned by them from time to time.

Pursuant to and in accordance with Rule 13(d)(1)(k) promulgated under the Securities Exchange Act of 1934, as amended, the Filers hereby agree to file a single statement on Schedule 13G and/or 13D (and any amendments thereto) on behalf of each of such parties, and hereby further agree to file this Joint Filing Agreement as an exhibit to such statement, as required by such rule.

This Joint Filing Agreement may be terminated by any of the Filers upon one week’s prior written notice or such lesser period of notice as the Filers may mutually agree.

Executed and delivered as of the date first above written.