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

Rhea-AI Filing Summary

Schedule 13D/A Amendment No. 6 filed by Dr. Weidong Yin discloses continued beneficial ownership of 6,359,500 Sinovac Biotech (SVA) common shares, representing 8.85 % of the 71.86 million shares outstanding as reported in the company’s 2023 Form 20-F.

The amendment adds one material update: on 10 July 2025 Sinovac announced a newly constituted 10-member Board of Directors that now includes Dr. Yin. He has accepted the appointment and intends to participate in the issuer’s future governance. Aside from this governance change, Dr. Yin states he currently has no specific plans that would trigger any of clauses (a)–(j) of Item 4 (e.g., mergers, asset sales, recapitalisations). He continues conversations with other shareholders on governance and value-enhancing matters but expressly disclaims acting as a group.

• Ownership structure: Sole voting and dispositive power over the entire 6.36 million-share position; no shared power disclosed.
• Funding source: Personal funds (“PF”).
• Citizenship: China.

No new contracts or arrangements regarding the securities are reported beyond those described in Item 4. The filing is signed by Dr. Yin on 14 July 2025.

Positive

• Founder-shareholder added to the Board, potentially improving governance alignment with minority investors.
• Stable 8.85 % ownership affirms continued commitment by a key insider.

Negative

• No immediate strategic plans or value-accretive actions were outlined, limiting near-term catalysts for shareholders.

Insights

Corporate Governance Expert

TL;DR: Major shareholder gains board seat; ownership steady at 8.85 %; limited immediate strategic signals.

Dr. Yin’s addition to Sinovac’s board formalises long-standing influence by the company’s founder-CEO. While the 8.85 % stake is unchanged, a board position can enhance oversight and strategic input, potentially aligning management decisions with shareholder interests. The absence of new activist intentions points to continuity rather than immediate restructuring. Investors should monitor forthcoming board actions, especially given prior governance disputes at Sinovac.

Securities Analyst

TL;DR: Filing signals governance update, but no change to ownership or financial outlook—impact neutral.

The Schedule 13D/A confirms Dr. Yin controls 6.36 million shares, unchanged from earlier amendments, equating to 8.85 % of outstanding stock. The sole new element is his acceptance of a board seat announced 10 July 2025. Because no incremental share purchases, sales, or financing arrangements are disclosed, the filing has no direct balance-sheet or dilution impact. Market reaction is likely muted unless subsequent board actions lead to strategic shifts or corporate events.

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

(Title of Class of Securities)

P8696W104

(CUSIP Number)

Weidong Yin
No. 39 Shangdi Xi Road, Haidian District
Beijing, F4, 100085
86-10-8289-0088

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

07/10/2025

(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

Weidong Yin

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)

PF

5

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

6

Citizenship or place of organization

CHINA

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 6,359,500.00
8	Shared Voting Power 0.00
9	Sole Dispositive Power 6,359,500.00
10	Shared Dispositive Power 0.00

11

Aggregate amount beneficially owned by each reporting person

6,359,500.00

12

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

13

Percent of class represented by amount in Row (11)

8.85 %

14

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person:

Comments to item 13: Calculation is based on 71,860,702 Common Shares of the Issuer outstanding as of March 31, 2024 according to the Issuer's annual report on Form 20-F for the fiscal year ended December 31, 2023 (the "2023 Annual Report").

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Shares
(b)	Name of Issuer: SINOVAC BIOTECH LTD.
(c)	Address of Issuer's Principal Executive Offices: No. 39 Shangdi Xi Rd, Haidian District, Beijing, CHINA , 100085.
Item 1 Comment: This Amendment No.6 to Schedule 13D is being filed on behalf of Weidong Yin (the "Reporting Person"), to amend the Schedule 13D relating to the common shares, par value $0.001 per share (the "Common Shares"), of Sinovac Biotech Ltd. (the "Issuer"), filed by the Reporting Person on February 7, 2008, as amended by Amendment No.1 to Schedule 13D filed on February 8, 2016, Amendment No.2 to Schedule 13D filed on June 27, 2017, Amendment No.3 to Schedule 13D filed on March 21, 2025, Amendment No.4 to Schedule 13D filed on April 30, 2025 and Amendment No.5 to Schedule 13D filed on June 20, 2025 (collectively, the "Original Schedule 13D"). The information in each Item below amends the information disclosed under the corresponding Item of the Original Schedule 13D. Except as amended and supplemented herein, the information set forth in the Original Schedule 13D remains unchanged. Capitalized terms used herein have meanings as assigned thereto in the Original Schedule 13D unless defined herein. The information set forth in response to each separate Item below shall be deemed to be a response to all Items where such information is relevant.
Item 4.	Purpose of Transaction
	Item 4 is hereby amended and supplemented to add the following: The Issuer announced on July 10, 2025 a new board of directors of the Issuer (the "Board"), comprising Mr. Simon Anderson, Mr. Shan Fu, Mr. Shuge Jiao, Mr. Chiang Li, Mr. Yuk Lam Lo, Mr. Yumin Qiu, Mr. Yu Wang, Ms. Rui-Ping Xiao, Mr. Andrew Y Yan (as Chairman of the Board) and the Reporting Person. The Reporting Person has accepted the appointment and plans to participate in the future governance of the Issuer as a member of the newly Board. Except as set forth in this Item 4, the Reporting Person has no present plan or intention that would resu lt in or relate to the listed transactions described in Item 4 of Schedule 13D. The Reporting Person has engaged and will continue to engage in discussions with other shareholders of the Issuer regarding the Board, the corporate governance and similar matters that the Reporting Person believes would increase shareholder value, and depending on the outcome of the discussion, the Reporting Person may pursue plans or proposals that relate to or would result in any of the matters set forth in clauses (a)-(j) of Item 4 of Schedule 13D. The filing of this Amendment shall not be construed as an admission that the Reporting Person, 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 Person expressly disclaims beneficial ownership of the common shares beneficially owned by other shareholders of the Issuer.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Item 6 is hereby amended and supplemented to add the following: Item 4 of Amendment No. 6 is incorporated herein by reference.

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.

Weidong Yin

Signature:	/s/ Weidong Yin
Name/Title:	Weidong Yin
Date:	07/14/2025

FAQ

How many Sinovac (SVA) shares does Dr. Weidong Yin own?

6,359,500 common shares, equal to 8.85 % of shares outstanding.

Did the filing report any new share purchases or sales by Dr. Yin?

No. The amendment shows ownership unchanged from prior filings.

What corporate role did Dr. Yin accept according to the Schedule 13D/A?

He joined Sinovac’s Board of Directors as announced on 10 July 2025.

Does Dr. Yin plan to pursue mergers or restructuring at Sinovac?

The filing states he has no present plans for actions under Item 4(a)-(j), but remains open to discussions.

What funding source was used for the share acquisition?

The filing lists personal funds (PF) as the source.