# EDGAR Filing Document

**Accession Number:** 0001472789
**File Stem:** 0001104659-25-067508
**Filing Date:** 2025-7
**Character Count:** 14004
**Document Hash:** 63ff887258628633962ec5ae7d924f51
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-25-067508.hdr.sgml**: 20250714

**ACCESSION NUMBER**: 0001104659-25-067508

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250714

**DATE AS OF CHANGE**: 20250714

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** SINOVAC BIOTECH LTD
- **CENTRAL INDEX KEY:** 0001084201
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** B9
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-79318
- **FILM NUMBER:** 251120062

**BUSINESS ADDRESS:**
- **STREET 1:** NO. 39 SHANGDI XI ROAD
- **STREET 2:** HAIDIAN DISTRICT
- **CITY:** BEIJING
- **STATE:** F4
- **ZIP:** 100085
- **BUSINESS PHONE:** 86-10-82890088

**MAIL ADDRESS:**
- **STREET 1:** NO. 39 SHANGDI XI ROAD
- **STREET 2:** HAIDIAN DISTRICT
- **CITY:** BEIJING
- **STATE:** F4
- **ZIP:** 100085

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NET FORCE SYSTEMS INC
- **DATE OF NAME CHANGE:** 19991110
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** SAIF Partners IV L.P.
- **CENTRAL INDEX KEY:** 0001472789

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** E9

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** SAIF PARTNERS, 2 PACIFIC PL., STE. 2115
- **STREET 2:** 88 QUEENSWAY
- **CITY:** HONG KONG
- **STATE:** K3
- **ZIP:** 00000
- **BUSINESS PHONE:** 852-2918-2205

**MAIL ADDRESS:**
- **STREET 1:** SAIF PARTNERS, 2 PACIFIC PL., STE. 2115
- **STREET 2:** 88 QUEENSWAY
- **CITY:** HONG KONG
- **STATE:** K3
- **ZIP:** 00000

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 19)**

**SINOVAC BIOTECH LTD.**

*(Name of Issuer)*

**Common Shares, par value US$0.001 per share**

*(Title of Class of Securities)*

**P8696W104**

*(CUSIP Number)*

**Andrew Y Yan**<br>c/o Suite 1102, Five Pacific Place<br>28 Hennessy Road, Wanchai<br>Hong Kong K3 00000<br>852 2918-2200

*(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)*

| **CUSIP No.** | **P8696W104** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**SAIF Partners IV L.P.** | Name of reporting person<br>**SAIF Partners IV L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**10780820.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**10780820.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**10780820.00** | Aggregate amount beneficially owned by each reporting person<br>**10780820.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**15.00%** | Percent of class represented by amount in Row (11)<br>**15.00%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for 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").

| **CUSIP No.** | **P8696W104** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**SAIF IV GP, L.P.** | Name of reporting person<br>**SAIF IV GP, L.P.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**10780820.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**10780820.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**10780820.00** | Aggregate amount beneficially owned by each reporting person<br>**10780820.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**15.00%** | Percent of class represented by amount in Row (11)<br>**15.00%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for 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 2023 Annual Report.

| **CUSIP No.** | **P8696W104** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**SAIF IV GP Capital Ltd.** | Name of reporting person<br>**SAIF IV GP Capital Ltd.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**CAYMAN ISLANDS** | Citizenship or place of organization<br>**CAYMAN ISLANDS** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**10780820.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**10780820.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**10780820.00** | Aggregate amount beneficially owned by each reporting person<br>**10780820.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**15.00%** | Percent of class represented by amount in Row (11)<br>**15.00%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

**Comment for 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 2023 Annual Report.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Shares, par value US$0.001 per share

**(b) Name of Issuer:**
SINOVAC BIOTECH LTD.

**(c) Address of Issuer's Principal Executive Offices:**
No. 39 Shangdi Xi Rd, Haidian District, Beijing, F4, 100085

This Amendment No.19 to Schedule 13D is being filed on behalf of each of SAIF Partners IV L.P., SAIF IV GP, L.P., and SAIF IV GP Capital Ltd. (each, a "Reporting Person," and collectively, the "Reporting Persons"), 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 Persons on May 31, 2011, as amended by Amendment No.1 to Schedule 13D filed on August 23, 2011, Amendment No.2 to Schedule 13D filed on September 30, 2011, Amendment No.3 to Schedule 13D filed on November 29, 2011, Amendment No.4 to Schedule 13D filed on December 30, 2011, Amendment No.5 to Schedule 13D filed on February 2, 2016, Amendment No. 6 to Schedule 13D filed on June 26, 2017, Amendment No. 7 to Schedule 13D filed on December 12, 2022, Amendment No. 8 to Schedule 13D filed on March 15, 2023, Amendment No. 9 to Schedule 13D filed on May 25, 2023, Amendment No. 10 to Schedule 13D filed on September 15, 2023, Amendment No. 11 to Schedule 13D filed on December 1, 2023, Amendment No. 12 to Schedule 13D filed on June 17, 2024, Amendment No. 13 to Schedule 13D filed on September 12, 2024, Amendment No. 14 to Schedule 13D filed on February 19, 2025, Amendment No. 15 to Schedule 13D filed on March 19, 2025, Amendment No. 16 to Schedule 13D filed on April 28, 2025, Amendment No. 17 to Schedule 13D filed on May 23, 2025, and Amendment No. 18 to Schedule 13D filed on June 17, 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 in previous amendments and 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 disclosed 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 Mr. Yin Weidong.

The Reporting Persons have also engaged and will continue to engage in discussions with other shareholders of the Issuer regarding the Board, the corporate governance of the Issuer and similar matters that the Reporting Persons believe would increase shareholder value, as well as pursue other 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 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 Board.

**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. 19 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.

**Reporting Person:** SAIF Partners IV L.P.

**Signature:** /s/Andrew Y Yan

**Name/Title:** Director of SAIF IV GP Capital Ltd., which is the General Partner of SAIF IV GP, L.P., which is the General Partner of SAIF Partners IV L.P.

**Date:** 07/14/2025

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.

**Reporting Person:** SAIF IV GP, L.P.

**Signature:** /s/Andrew Y Yan

**Name/Title:** Director of SAIF IV GP Capital Ltd., which is the General Partner of SAIF IV GP, L.P.

**Date:** 07/14/2025

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.

**Reporting Person:** SAIF IV GP Capital Ltd.

**Signature:** /s/Andrew Y Yan

**Name/Title:** Director of SAIF IV GP Capital Ltd.

**Date:** 07/14/2025