[SCHEDULE 13D/A] HilleVax, Inc. SEC Filing

Rhea-AI Filing Summary

Frazier-affiliated reporting persons filed Amendment No. 5 to their Schedule 13D for HilleVax, Inc. (HLVX). The amendment reports that XOMA Royalty Corporation and its subsidiary entered into a merger agreement and commenced a tender offer to acquire all outstanding HilleVax common shares for $1.95 in cash per share plus one non-transferable contingent value right (CVR). The Offer expired September 15, 2025, and on September 17, 2025 Purchaser accepted all validly tendered shares and completed a merger under Delaware law, leaving HilleVax as a wholly owned subsidiary of Purchaser.

At the Effective Time each Share held by the reporting persons converted into the right to receive the stated Offer Price. The Merger Agreement also provided that any outstanding stock option with an exercise price greater than the Offer Price was canceled for no consideration, which included options held by Mr. Heron. As of September 17, 2025 the reporting persons ceased to be beneficial owners of more than 5% of the class.

Positive

• Acquisition completed: Purchaser accepted valid tenders and completed the merger, converting reported shares into the stated Offer Price.
• Certainty of cash consideration: Reporting persons received $1.95 cash per share plus one CVR per share.
• Reporting threshold change: As of September 17, 2025 the reporting persons ceased to be beneficial owners of more than 5% of the class.

Negative

• Cancellation of options: All outstanding stock options with exercise prices greater than the Offer Price were canceled for no consideration, including options held by Patrick J. Heron.
• Loss of public ownership: Merger resulted in HilleVax becoming a wholly owned subsidiary of Purchaser, eliminating the public float for remaining shareholders who did not receive cash/CVR through the offer.

Insights

M&A Specialist

TL;DR: The tender offer and merger completed, converting shares to $1.95 cash plus CVR and delivering full ownership to Purchaser.

The filing documents a completed acquisition structure where Purchaser executed a tender offer followed by a short-form merger under Delaware law, achieving 100% control of HilleVax through acceptance of valid tenders and a Section 251(h) merger. The offer consideration consists of fixed cash plus contingent value rights, preserving potential upside tied to the CVR. The replacement of equity with cash and CVRs crystallizes value for shareholders who tendered but eliminates public float and typical minority protections going forward. Cancellation of options with exercise prices above $1.95 removed upside for option holders and simplifies the post-closing capital structure.

Corporate Governance Expert

TL;DR: Transaction closed via tender offer and short-form merger; reporting persons no longer hold >5% and certain options were canceled.

The amendment is a routine post-closing disclosure updating ownership and transaction effects. It confirms that the reporting group received the Offer Price and that their beneficial ownership fell below the 5% reporting threshold as of the Effective Time. The filing also documents the contractual cancellation of in-the-money options for no consideration, a material governance outcome for option holders but a standard contractual provision in many acquisition agreements. The disclosure does not present new litigation, financing, or governance disputes.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 5)

HILLEVAX, INC.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

43157M102

(CUSIP Number)

Steve R. Bailey
601 Union Street, Suite 3200,
Seattle, WA, 98101
(206) 621-7200

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

09/17/2025

(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.

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. 43157M102

1

Name of reporting person

Frazier Life Sciences Public Fund, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLSP, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLSP, L.L.C.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

Frazier Life Sciences Public Overage Fund, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLSP Overage, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLSP Overage, L.L.C.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

Frazier Life Sciences X, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLS X, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLS X, L.L.C.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

Frazier Life Sciences XI, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

WC

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLS XI, L.P.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

PN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

FHMLS XI, L.L.C.

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

OO

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

James N. Topper

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

Patrick J. Heron

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

Albert Cha

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

James Brush

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

CUSIP No. 43157M102

1

Name of reporting person

Daniel Estes

2

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

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

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

6

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

11

Aggregate amount beneficially owned by each reporting person

0.00

12

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

13

Percent of class represented by amount in Row (11)

0.0 %

14

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.0001 per share
(b)	Name of Issuer: HILLEVAX, INC.
(c)	Address of Issuer's Principal Executive Offices: 321 Harrison Avenue, Boston, MASSACHUSETTS , 02118.
Item 1 Comment: This Amendment No. 5 ("Amendment No. 5") to Schedule 13D amends the statement on Schedule 13D filed on May 6, 2022 (the "Original Schedule 13D") as amended on September 8, 2022, May 5, 2023, September 27, 2023 and May 31, 2024 (the "Prior Amendments", and together with the Original Schedule 13D and this Amendment No. 5, the "Schedule 13D"). Except as otherwise specified in Amendment No. 5, all items in the Original Schedule 13D, as amended by the Prior Amendments, are unchanged. All capitalized terms used in this Amendment No. 5 and not otherwise defined herein have the meanings ascribed to such terms in the Original Schedule 13D, as amended by the Prior Amendments.
Item 4.	Purpose of Transaction
	Item 4 of the Schedule 13D is hereby amended to incorporate the following at the end thereof: On August 4, 2025, the Issuer, XOMA Royalty Corporation ("Purchaser") and XRA 4 Corp., a wholly owned subsidiary of Purchaser ("Merger Sub") entered into an Agreement and Plan of Merger (the "Merger Agreement"). Pursuant to the Merger Agreement, upon the terms and subject to the conditions thereof, Purchaser commenced a tender offer (the "Offer") to acquire all of the outstanding shares of Common Stock of the Issuer (the "Shares"), at an offer price of (i) $1.95 in cash, without interest, plus (ii) one non-transferable contractual contingent value right per Share (collectively, the "Offer Price"). The Offer expired at the end of the day, one minute after 11:59 p.m. Eastern Time, on September 15, 2025. On September 17, 2025, Purchaser accepted for purchase all shares of Common Stock that were validly tendered and not validly withdrawn in accordance with the terms of the Offer, which included the Shares that were held by the Reporting Persons. On September 17, 2025, upon the terms and subject to the conditions set forth in the Merger Agreement and in accordance with Section 251(h) of the Delaware General Corporation Law, Merger Sub merged with and into the Issuer, with the Issuer surviving as a wholly owned subsidiary of Purchaser (the "Merger"), without a meeting or vote of stockholders of the Issuer (the "Effective Time"). At the Effective Time, the Shares held by the Reporting Persons were each converted into the right to receive the Offer Price. In addition, pursuant to the Merger Agreement, at the Effective Time, each outstanding stock option, whether vested or unvested, that had an exercise price per Share that was greater than the Offer Price was canceled for no consideration. This included the stock options held by Heron.
Item 5.	Interest in Securities of the Issuer
(a)	The information contained in Rows 7, 8, 9, 10, 11, and 13 of each Reporting Person's cover page to this Schedule 13D is incorporated by reference into this Item 5. Except as specifically stated herein, the filing of this Schedule 13D shall not be construed as an admission that any Reporting Person or any of the foregoing is, for the purposes of Section 13(d) and/or Section 13(g) of the Act or otherwise, the beneficial owner of any securities covered by this Schedule 13D or a member of a "group" with any other person.
(b)	The information contained in Rows 7, 8, 9, 10, 11, and 13 of each Reporting Person's cover page to this Schedule 13D is incorporated by reference into this Item 5.
(c)	Except as disclosed in Item 4 of this Schedule 13D, none of the Reporting Persons has effected any transactions relating to the Common Stock during the past 60 days.
(e)	As of September 17, 2025, the Reporting Persons ceased to be beneficial owners of more than five percent of the Shares.
Item 7.	Material to be Filed as Exhibits.
	Exhibit 99.1 Joint Filing Agreement (incorporated by reference to Exhibit A to Schedule 13D/A filed on May 31, 2024)

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.

Frazier Life Sciences Public Fund, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLSP, L.L.C., GP of FHMLSP, L.P., GP of Frazier Life Sciences Public Fund, L.P.
Date:	09/17/2025

FHMLSP, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLSP, L.L.C., GP of FHMLSP, L.P.
Date:	09/17/2025

FHMLSP, L.L.C.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLSP, L.L.C.
Date:	09/17/2025

Frazier Life Sciences Public Overage Fund, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLSP Overage, L.L.C., GP of FHMLSP Overage, L.P., GP of Frazier Life Sciences Public Overage Fund, L.P.
Date:	09/17/2025

FHMLSP Overage, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLSP Overage, L.L.C., GP of FHMLSP Overage, L.P.
Date:	09/17/2025

FHMLSP Overage, L.L.C.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLSP Overage, L.L.C.
Date:	09/17/2025

Frazier Life Sciences X, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLS X, L.L.C., GP of FHMLS X, L.P., GP of Frazier Life Sciences X, L.P.
Date:	09/17/2025

FHMLS X, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLS X, L.L.C., GP of FHMLS X, L.P.
Date:	09/17/2025

FHMLS X, L.L.C.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLS X, L.L.C.
Date:	09/17/2025

Frazier Life Sciences XI, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLS XI, L.L.C., GP of FHMLS XI, L.P., GP of Frazier Life Sciences XI, L.P.
Date:	09/17/2025

FHMLS XI, L.P.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLS XI, L.L.C., GP of FHMLS XI, L.P.
Date:	09/17/2025

FHMLS XI, L.L.C.

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, CFO of FHMLS XI, L.L.C.
Date:	09/17/2025

James N. Topper

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, Attorney-in-Fact for James N. Topper, pursuant to a Power of Attorney, a copy of which was filed with the SEC on July 31, 2017
Date:	09/17/2025

Patrick J. Heron

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, Attorney-in-Fact for Patrick J. Heron, pursuant to a Power of Attorney, a copy of which was filed with the SEC on July 31, 2017
Date:	09/17/2025

Albert Cha

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, Attorney-in-Fact for Albert Cha, pursuant to a Power of Attorney, a copy of which was filed with the SEC on August 16, 2021
Date:	09/17/2025

James Brush

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, Attorney-in-Fact for James Brush, pursuant to a Power of Attorney, a copy of which was filed with the SEC on August 16, 2021
Date:	09/17/2025

Daniel Estes

Signature:	/s/ Steve R. Bailey
Name/Title:	By Steve R. Bailey, Attorney-in-Fact for Daniel Estes, pursuant to a Power of Attorney, a copy of which was filed with the SEC on April 18, 2022
Date:	09/17/2025

FAQ

What consideration did HLVX shareholders receive in the transaction?

Shareholders received $1.95 in cash per share plus one non-transferable contractual contingent value right (CVR) per share.

When did the tender offer and merger become effective for HilleVax (HLVX)?

The Offer expired on September 15, 2025, and Purchaser accepted validly tendered shares and completed the merger on September 17, 2025.

Did the reporting persons retain more than 5% ownership after the merger?

No. As of September 17, 2025 the reporting persons ceased to be beneficial owners of more than 5% of the class.

What happened to outstanding stock options as part of the merger?

Any outstanding stock option with an exercise price per share greater than the Offer Price was canceled for no consideration, including options held by Mr. Heron.

Who signed the Schedule 13D/A on behalf of the reporting entities?

Steve R. Bailey signed on behalf of the Frazier-affiliated entities in his capacities including CFO and as attorney-in-fact, dated September 17, 2025.