[SCHEDULE 13D/A] Sinovac Biotech, Ltd SEC Filing

Rhea-AI Filing Summary

Vivo Capital VIII, LLC and Vivo Capital IX, LLC filed Amendment No. 6 to their Schedule 13D regarding Sinovac Biotech Ltd. (NASDAQ: SVA) on 11 July 2025. The filing updates share ownership and details an ongoing proxy and litigation battle over control of Sinovac’s board.

Ownership: Vivo Capital VIII reports 1,361,236 common shares (1.9%); Vivo Capital IX reports 4,541,764 common shares (6.3%), based on 71,860,702 shares outstanding, for a combined 8.2% economic interest. Both entities have shared voting and dispositive power over their respective holdings.

Purpose of transaction: The amendment narrates events surrounding a Special Meeting called for 8 July 2025. Sinovac sought a court injunction to exclude Vivo and another investor from voting. Vivo opposed the injunction; the Eastern Caribbean Court of Appeal stayed enforcement on 8 July, enabling Vivo to vote its shares by proxy in favor of SAIF’s director slate (including Mr. Shan Fu). Sinovac disclosed on 10 July 2025 that the SAIF-backed slate was elected and Mr. Fu joined the board.

Vivo states it will continue to engage with other shareholders and pursue actions under Item 4 of Schedule 13D, such as influencing board composition, dividend policy, auditor replacement, SEC filing compliance, and a potential NASDAQ relisting. Vivo also references multiple legal proceedings, including a 30 June 2025 U.S. District Court injunction compelling disclosure from shareholders linked to Sinovac’s chairman.

Exhibits: Two press releases (2 July 2025 and 9 July 2025) describing the legal developments are incorporated by reference.

Implications for investors: The filing confirms an activist position totaling 8.2% of Sinovac’s equity and outlines continuing efforts to reshape governance. While successful in electing a new board slate, persistent litigation indicates ongoing uncertainty around corporate control and future strategic direction.

Positive

• Vivo Capital secured court relief enabling full voting rights at the 8 July 2025 Special Meeting.
• SAIF-backed director slate, supported by Vivo, was successfully elected, altering Sinovac’s board composition.
• Activist investors now control a combined 8.2% stake, potentially driving governance and strategic changes.

Negative

• Multiple ongoing legal proceedings in several jurisdictions create continued uncertainty and potential costs.
• Issuer previously attempted to block Vivo’s voting rights, signalling entrenched management resistance.
• Sinovac remains non-compliant with SEC reporting and is suspended from NASDAQ, issues still unresolved.

Insights

Equity Research Analyst

TL;DR – Vivo now controls 8.2% of SVA and helped install a new board; governance gains offset by ongoing legal risk.

The amendment shows Vivo Capital’s combined 5.9 million shares and shared voting power, establishing it as a significant activist bloc. The successful election of the SAIF-nominated board—achieved after a court-ordered stay—marks a material governance change that may unlock value via improved transparency, dividend policy, and pursuit of NASDAQ relisting. However, continuous litigation in Antigua, the Eastern Caribbean, and U.S. courts heightens uncertainty, potentially consuming management focus and resources. Overall impact is moderately positive but contingent on litigation outcomes and board effectiveness.

Corporate Governance Specialist

TL;DR – Filing highlights an intensifying control contest; fresh board seats gained, but courtroom battles persist.

This 13D/A signals a classic activist campaign. Vivo leveraged legal avenues to secure voting rights, succeeded in electing its preferred director, and pledges further influence over Sinovac’s auditing, reporting, and listing status. The move strengthens minority shareholder representation, yet the issuer’s attempt to disenfranchise key holders underscores deep governance fractures. Continuous injunctions and appeals could delay operational reforms and amplify regulatory scrutiny. Investors should monitor upcoming court decisions and whether the new board delivers tangible governance and financial improvements.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 6)

Sinovac Biotech Ltd.

(Name of Issuer)

Common Shares, $0.001 par value per share

(Title of Class of Securities)

P8696W104

(CUSIP Number)

Vivo Capital, LLC
192 Lytton Avenue,
Palo Alto, CA, 94301
(650) 688-0818

Stephen Blake
Simpson Thacher & Bartlett LLP,, 2475 Hanover Street
Palo Alto, CA, 94304
650-251-5000

Bryan Jin
Simpson Thacher & Bartlett LLP,, 2475 Hanover Street
Palo Alto, CA, 94304
650-251-5000

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

07/11/2025

(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. P8696W104

1

Name of reporting person

Vivo Capital VIII, LLC

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)

OO

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 1,361,236.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,361,236.00

11

Aggregate amount beneficially owned by each reporting person

1,361,236.00

12

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

13

Percent of class represented by amount in Row (11)

1.9 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

The beneficial ownership reported herein reflects that 1,196,073 of such shares are held by Vivo Capital Fund VIII, L.P. and 165,163 of such shares are held by Vivo Capital Surplus Fund VIII, L.P. Vivo Capital VIII, LLC is the general partner of both Vivo Capital Fund VIII, L.P. and Vivo Capital Surplus Fund VIII, L.P. The beneficial ownership percentage reported herein is based on 71,860,702 common shares outstanding as of March 31, 2024, as reported in the Issuer's Form 20-F filed with the Securities and Exchange Commission on April 29, 2024.

SCHEDULE 13D

CUSIP No. P8696W104

1

Name of reporting person

Vivo Capital IX, LLC

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)

OO

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 4,541,764.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,541,764.00

11

Aggregate amount beneficially owned by each reporting person

4,541,764.00

12

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

13

Percent of class represented by amount in Row (11)

6.3 %

14

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person:

The beneficial ownership reported herein reflects that such shares are held by Vivo Capital Fund IX, L.P. Vivo Capital IX, LLC is the general partner of Vivo Capital Fund IX, L.P. The beneficial ownership percentage reported herein is based on 71,860,702 common shares outstanding as of March 31, 2024, as reported in the Issuer's Form 20-F filed with the Securities and Exchange Commission on April 29, 2024.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Shares, $0.001 par value per share
(b)	Name of Issuer: Sinovac Biotech Ltd.
(c)	Address of Issuer's Principal Executive Offices: No. 39 Shangdi Xi Road, Haidian District, Beijing, CHINA , 100085.
Item 1 Comment: Reference is hereby made to the statement on Schedule 13D filed with the Securities and Exchange Commission on July 11, 2018 by Vivo Capital, LLC with respect to the Common Shares, par value $0.001 per share ("Common Shares") of Sinovac Biotech Ltd. (the "Issuer"), Amendment No. 1 thereto filed by Vivo Capital, LLC and Vivo Capital VIII, LLC on July 20, 2018, Amendment No. 2 thereto filed by Vivo Capital, LLC, Vivo Capital VIII, LLC and Vivo Capital IX, LLC on August 27, 2018, Amendment No. 3 thereto filed by Vivo Capital VIII, LLC and Vivo Capital IX, LLC on March 19, 2025, Amendment No. 4 thereto filed by Vivo Capital VIII, LLC and Vivo Capital IX, LLC on April 24, 2025, and Amendment No. 5 thereto filed by Vivo Capital VIII, LLC and Vivo Capital IX, LLC on June 13, 2025 (as so amended, the "Schedule 13D"). The Items herein amend the information disclosed under the corresponding Items of the Schedule 13D as described herein. Capitalized terms used herein and not otherwise defined have the meanings ascribed to them in the Schedule 13D.
Item 4.	Purpose of Transaction
	Item 4 is hereby supplemented and amended by adding the following: On May 19, 2025, the Issuer gave notice of a Special Meeting of Shareholders to be held on July 8, 2025 and announced an intention to exclude shares held by the Reporting Persons and another investor from the vote. On May 30, 2025, the Issuer filed an application for an injunction in the High Court of Antigua and Barbuda seeking an order prohibiting the Reporting Persons and the other investor from voting their shares at the Special Meeting. The Reporting Persons have opposed such an injunction in the High Court and the Court of Appeal of the Eastern Caribbean Supreme Court, and, on July 8, 2025, the Court of Appeal issued an order staying execution of an injunction from the High Court. In light of the Court of Appeal's stay order, the Reporting Persons exercised their rights as registered shareholders of Sinovac to vote by proxy in support of SAIF's proposed slate of directors at the Special Meeting, including Mr. Shan Fu. The Issuer disclosed on July 10, 2025 that a new Board of Directors consisting of the SAIF nominated slate, including Mr. Fu was elected at the Special Meeting of the Company held on July 8, 2025. Mr. Fu has accepted the appointment and plans to participate in the future governance of Sinovac as a member of the newly elected Board of Directors as of July 8, 2025. The Reporting Person has continued to engage in discussions with other shareholders about the board, the future of the Issuer and the Special Meeting, including with other shareholders who have also been advocating for changes to the board. The Reporting Persons have also been involved in multiple legal proceedings related to the future of Sinovac, their shareholdings and the composition of the Board of Directors. On June 30, 2025, the Reporting Persons obtained an injunction from the United States District Court for the District of Massachusetts, compelling further disclosure from other Sinovac shareholders affiliated with Sinovac's Chairman Mr. Li. Other legal proceedings are continuing. Vivo Capital, an affiliate of the Reporting Persons, issued press releases related to the legal proceedings described above, which are attached as Exhibits K and L and incorporated herein by reference. The Reporting Persons will continue to seek to influence management of the Issuer or its Board of Directors with respect to the business and affairs of the Issuer and may from time to time pursue or propose actions to the Issuer, other shareholders or other persons. The Reporting Persons' pursuit of such matters relate to or would result in actions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D, including, but not limited to, changes in the present Board of Directors or management of the Issuer, changes in the present capitalization or dividend policy of the Issuer, changes in the Issuer's business or corporate structure, changes in the Issuer's charter, bylaws, or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person, and changes that will relate to the listing of the Issuer's securities on a national securities exchange. The Reporting Persons will continue to engage in discussions with other shareholders concerning some or all of such matters, particularly about the Board and the future of the Issuer, including the Issuer's payment of dividends to all shareholders and steps necessary for the Issuer to retain a new independent auditing firm, become current in its SEC report and obtain resumption of trading on NASDAQ. The filing of this Amendment shall not be construed as an admission that the Reporting Persons and their affiliates, on the one hand, and any other shareholders of the Issuer and their affiliates, on the other hand, are a group, or have agreed to act as a group with each other for purposes of Section 13(d) of the Act or for any other purpose. The Reporting Persons expressly disclaim beneficial ownership of the common shares beneficially owned by other shareholders who may also be advocating for changes to the New Board.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Item 6 is hereby supplemented and amended by adding the following: Item 6 of the Schedule 13D is hereby supplemented and amended to incorporate by reference the information set forth in Item 4 to this Amendment No. 5 to Schedule 13D.
Item 7.	Material to be Filed as Exhibits.
	Item 7 is hereby supplemented and amended by adding the following: Exhibit No. Description K Press Release dated July 2, 2025* L Press Release dated July 9, 2025* * Filed herewith

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.

Vivo Capital VIII, LLC

Signature:	/s/ Dr. Frank Kung
Name/Title:	Dr. Frank Kung, Managing Member
Date:	07/11/2025

Vivo Capital IX, LLC

Signature:	/s/ Dr. Frank Kung
Name/Title:	Dr. Frank Kung, Managing Member
Date:	07/11/2025

FAQ

How many Sinovac shares does Vivo Capital own?

Vivo Capital VIII owns 1,361,236 shares (1.9%) and Vivo Capital IX owns 4,541,764 shares (6.3%), totaling about 8.2%.

What was the key outcome of Sinovac’s 8 July 2025 Special Meeting?

A new board slate nominated by SAIF and backed by Vivo, including Mr. Shan Fu, was elected.

Why did Vivo Capital file this Schedule 13D/A amendment?

To update its beneficial ownership and detail recent legal actions and board changes following the Special Meeting.

What legal actions are mentioned in the filing?

They include an Antigua & Barbuda injunction attempt, an Eastern Caribbean Court of Appeal stay, and a U.S. District Court injunction dated 30 June 2025.

What future actions does Vivo intend to pursue?

Vivo plans to influence board composition, dividend policy, auditor selection, SEC compliance, and NASDAQ relisting efforts.