SCHEDULE 13D/A 0001650757 XXXXXXXX LIVE 2 Common Shares 07/08/2025 true 0001084201 P8696W104 SINOVAC BIOTECH LTD.

No. 39 Shangdi Xi Road, Haidian District Beijing F4 100085

Xingluo Zhu 86-10-8593-5676 Suite 1707-08, 17/F, One Exchange Square 8 Connaught Place, Central Hong Kong K3 000000 0001650757 N Advantech Capital L.P. b WC N E9 0.00 5851423.00 0.00 5851423.00 5851423.00 N 8.14 PN Comments to item 13: 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"). Y Advantech Capital Partners Ltd. b WC N E9 0.00 5851423.00 0.00 5851423.00 5851423.00 N 8.14 CO Comments to item 13: Based on 71,860,702 Common Shares of the Issuer outstanding as of March 31, 2024 according to the 2023 Annual Report. Y Green Vision Partners Limited b WC N E9 0.00 5851423.00 0.00 5851423.00 5851423.00 N 8.14 CO Comments to item 13: Based on 71,860,702 Common Shares of the Issuer outstanding as of March 31, 2024 according to the 2023 Annual Report. Y Prime Success, L.P. b WC N E9 0.00 5851423.00 0.00 5851423.00 5851423.00 N 8.14 PN Comments to item 13: Based on 71,860,702 Common Shares of the Issuer outstanding as of March 31, 2024 according to the 2023 Annual Report. Common Shares SINOVAC BIOTECH LTD. No. 39 Shangdi Xi Road, Haidian District Beijing F4 100085 This Amendment No.2 to Schedule 13D is being filed on behalf of Advantech Capital L.P., Advantech Capital Partners Ltd., Green Vision Partners Limited and Prime Success, L.P. (each, a "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 Persons on March 25, 2025, as amended by Amendment No. 1 filed by the Reporting Persons on April 10, 2025 (collectively, the "Original Schedule 13D"). The items herein amend the information disclosed under the corresponding items of the Original Schedule 13D. Capitalized terms used herein and not otherwise defined have the meanings given to them in the Original Schedule 13D. Item 4 is hereby supplemented and amended by adding the following: On July 7, 2025, the High Court of Antigua and Barbuda granted an interim injunction prohibiting the Reporting Persons and certain other shareholders from voting their shares at the Special Meeting (the "Injunction Order"). On July 8, 2025, the Court of Appeal of the Eastern Caribbean Supreme Court issued an order staying the Injunction Order (the "Stay Order"). After the Court of Appeal issued the Stay Order, the Special Meeting of Shareholders of the Issuer requisitioned by SAIF Partners IV L.P. ("SAIF") (the "Special Meeting") was convened. Mr. Chiang Li delivered a short statement and then purported to adjourn the Special Meeting. The Reporting Persons understand that the shareholders attending the Special Meeting then continued with the Special Meeting chaired by an incumbent director of the Issuer. The Reporting Persons voted their shares by proxy in favor of SAIF's proposals at the Special Meeting. The Reporting Persons understand that the shareholders of the Issuer approved both of SAIF's proposals at the Special Meeting and elected the nominees proposed by SAIF, including Mr. Yumin Qiu, a partner of Advantech Capital, to be the directors of the Issuer. Mr. Yumin Qiu accepted the appointment and intends to serve as a member of the board of directors of the Issuer. The Reporting Persons understand that on July 10, 2025, the previous directors removed at the Special Meeting issued a press release disputing the election results of the Special Meeting, and on July 11, 2025, the new board of directors of the Issuer elected at the Special Meeting issued a press release announcing the convening of the first board meeting. Except as set forth herein as may be necessary for defending their lawful interests in the Issuer in relation to the 2018 Private Placement, either alone or in coordination with any one or more shareholders of the Issuer, the Reporting Persons have no present plan or intention that would result in or relate to any of the transactions described in clauses (a) through (j) of Item 4 of Schedule 13D. Depending on discussions with other shareholders of the Issuer, the financial condition, results of operations and prospects of the Issuer and other factors that the Reporting Persons deem relevant, the Reporting Persons may take steps and pursue other plans or proposals that relate to or would result in any of the matters set forth in clauses (a) through (j) of Item 4 of Schedule 13D. The filing of this Amendment No. 2 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 of the Issuer. Not applicable. Item 6 is hereby supplemented and amended by adding the following: Item 4 of this Amendment No. 2 to Schedule 13D is incorporated herein by reference. Advantech Capital L.P. /s/ Yan Yang 07/14/2025 Advantech Capital Partners Ltd. /s/ Yan Yang 07/14/2025 Green Vision Partners Limited /s/ Yan Yang 07/14/2025 Prime Success, L.P. /s/ Yan Yang 07/14/2025