Sec Form 4 Filing - TAKEDA PHARMACEUTICAL CO LTD @ HilleVax, Inc. - 2025-09-17

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person TAKEDA PHARMACEUTICAL CO LTD 2. Issuer Name and Ticker or Trading Symbol HilleVax, Inc. [ HLVX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 1-1, NIHONBASHI-HONCHO 2-CHOME 3. Date of Earliest Transaction (MM/DD/YY) 09/17/2025 (Street) CHUO-KU, TOKYO, M0103-8668 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 09/17/2025 U 6,724,000 D $ 1.95 ( 1 ) 0 I See Explanation of Responses ( 2 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other TAKEDA PHARMACEUTICAL CO LTD 1-1, NIHONBASHI-HONCHO 2-CHOME CHUO-KU, TOKYO, M0103-8668 X Takeda Vaccines, Inc. 75 SIDNEY STREET CAMBRIDGE, MA02139 X Signatures /s/ Paul Sundberg, Authorized Signatory, Takeda Pharmaceutical Company Limited 09/19/2025 Signature of Reporting Person Date /s/ Max Heuer, Authorized signatory, Takeda Vaccines, Inc. 09/19/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These shares were sold pursuant to the cash tender offer (the "Tender Offer") by XOMA Royalty Corporation, a Nevada corporation ("Parent") and XRA 4 Corp., a Delaware corporation and a wholly owned subsidiary of Parent, to purchase all of the outstanding shares of common stock of the Issuer at an offer price of (i) $1.95 per share of common stock and (ii) one non-transferable contractual contingent value right. The Tender Offer expired as scheduled at one minute after 11:59 p.m., Eastern Time, on September 15, 2025 (the "Expiration Time") and closing of the Tender Offer was announced on September 17, 2025. As all conditions to the Tender Offer were satisfied or waived, on September 17, 2025, Parent irrevocably accepted for payment all shares validly tendered into and not validly withdrawn from the Tender Offer and paid for all such shares in accordance with the Tender Offer. ( 2 )Takeda Pharmaceutical Company Limited has beneficial ownership of the reported securities, all of which are held directly by Takeda Vaccines, Inc., an indirect wholly-owned subsidiary of Takeda Pharmaceutical Company Limited. Takeda Vaccines, Inc. is owned directly by Takeda Pharmaceuticals U.S.A., Inc., which is owned directly by both Takeda Pharmaceutical Company Limited (72.70%) and Takeda Pharmaceuticals International AG (27.30%). Takeda Pharmaceuticals International AG is a wholly-owned direct subsidiary of Takeda Pharmaceutical Company Limited.

Remarks: Intentional misstatements or omissions of facts constitute Federal Criminal Violations.

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).

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