Item 4 of the Original Schedule 13D is hereby amended and supplemented by the following: On June 10, 2025 (Beijing time), an extraordinary general meeting of shareholders of the Issuer was held at the Issuer's office at at No. 76 Zhichun Road, Haidian District, Beijing, People's Republic of China. At the extraordinary general meeting, the shareholders of the Issuer authorized and approved the Merger Agreement, the plan of merger required to be filed with the Registrar of Companies of the Cayman Islands (the "Plan of Merger") and the transactions contemplated by the Merger Agreement, including the Merger. On June 16, 2025, the Issuer and Merger Sub filed the Plan of Merger with the Registrar of Companies of the Cayman Islands, which was registered by the Registrar of Companies of the Cayman Islands as of June 16, 2025, pursuant to which the Merger became effective on June 16, 2025 (the "Effective Time"). As a result of the Merger, the Issuer became a wholly owned subsidiary of Parent. At the Effective Time, each ordinary share of the Issuer issued and outstanding immediately prior to the Effective Time was cancelled in exchange for the right to receive US$0.5 in cash without interest, except for (i) shares held by the Reporting Persons, (ii) shares held by the Issuer or any subsidiary of the Issuer or held in the Issuer's treasury, in each case, immediately prior to the Effective Time, and (iii) shares held by shareholders who had validly exercised and not effectively withdrawn or lost their rights to dissent from the Merger pursuant to Section 238 of the Companies Act of the Cayman Islands, which were cancelled and ceased to exist in exchange for the right to receive the payment of fair value of such shares in accordance with Section 238 of the Companies Act of the Cayman Islands. As a result of the Merger, the Issuer's ADSs ceased to trade on the Nasdaq Global Select Market after June 16, 2025. The Issuer has requested the Nasdaq to file an application on Form 25 with the SEC to notify the SEC of the delisting of the ADSs on the Nasdaq and deregistration of the Issuer's registered securities. The deregistration will become effective in 90 days after the filing of Form 25 or such shorter period as may be determined by the SEC. The Issuer's reporting obligations under the Exchange Act will be suspended upon the Company's filing of a certification and notice on Form 15 with the SEC, and will terminate once the deregistration becomes effective. Accordingly, this Amendment No. 6 constitutes an exit filing for the Reporting Persons.

As a result of the Merger, as described in Item 4 of this Amendment, the Reporting Persons do not beneficially own any securities of the Issuer identified pursuant to Item 1 or have any voting power or dispositive power over any securities of the Issuer identified pursuant to Item 1.

See Item 5(a) above.

Except as disclosed in this statement, none of the Reporting Persons has effected any transaction in the ordinary shares of the Issuer during the past 60 days.

Not applicable.

June 16, 2025