Entry into a Material Definitive Agreement. On August 11, 2026, ArriVent BioPharma, Inc. (the “Company”) entered into a Collaboration and License Agreement (the “Allist License Agreement”) with Shanghai Allist Pharmaceuticals Co., Ltd. (“Allist”), a pharmaceutical company incorporated under the laws of China. Pursuant to the Allist License Agreement, the Company granted Allist an exclusive, sublicensable (through multiple tiers), royalty-bearing license under certain intellectual property own…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

Other Events. On May 11, 2026, ArriVent BioPharma, Inc. (the “Company”) filed with the Securities and Exchange Commission (the “SEC”) a prospectus supplement (the “Prospectus Supplement”), dated May 11, 2026, with respect to the Company’s existing “at the market offering” program (the “ATM Program”). Pursuant to the Prospectus Supplement, the Company may offer and sell shares of its common stock having an aggregate offering price of up to $250,000,000, from time to time, through Jefferies LLC…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

Entry into a Material Definitive Agreement. On July 1, 2025, ArriVent BioPharma, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Goldman Sachs & Co. LLC, Citigroup Global Markets Inc., and Guggenheim Securities, LLC as representatives of the several underwriters named therein (the “Underwriters”), relating to the issuance and sale in an underwritten public offering (the “Offering”) by the Company of an aggregate of 2,482,692 shares (the “Firm Sh…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

Director — Carl L. Gordon, Ph.D., CFA: Dr. Gordon decided not to stand for re-election and was succeeded by Dr. Parsey.

Changes in the Registrant’s Certifying Accountant. (a) Dismissal of Previous Independent Registered Public Accounting Firm ​ On March 11, 2025, the Audit Committee (the “Audit Committee”) of the Board of Directors of ArriVent BioPharma, Inc. (the “Company”) approved the dismissal of KPMG LLP (“KPMG”) as the Company’s independent registered public accounting firm. The dismissal was not related to any disagreements with KPMG on any matter of accounting principles or practices, financial stateme…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

Entry into a Material Definitive Agreement. On January 21, 2025, ArriVent BioPharma, Inc. (the “Company”) entered into an Exclusive License Agreement (the “Lepu Biopharma Agreement”) with Lepu Biopharma Co., Ltd. (“Lepu Biopharma”), pursuant to which Lepu Biopharma granted the Company a right to develop and commercialize MRG007, an antibody drug conjugate for gastrointestinal cancers outside greater China, which is mainland China, Hong Kong, Macau and Taiwan (“Greater China”). Under the Lepu…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

Director on Nominating and Corporate Governance Committee and Compensation Committee — John Hohneker, M.D.: Dr. Hohneker was appointed to additional board committees.

Entry into a Material Definitive Agreement. On June 4, 2024 , ArriVent BioPharma, Inc. (the “Company”) entered into a Research and Collaboration Agreement with Jiangsu Alphamab Biopharmaceuticals Co., Ltd. (“Alphamab”), a wholly owned subsidiary of Alphamab Oncology, pursuant to which the Company and Alphamab will discover, develop and commercialize novel antibody drug conjugates for the treatment of cancers (the “Alphamab Agreement”). Under the Alphamab Agreement, and subject to the Company’…

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…

Director — Kristine Peterson: Ms. Peterson was appointed to the Board of Directors.

and in the press release furnished as Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, or incorporated by reference in any filing with the U.S. Securities and Exchange Commission made by the Company, whether made before or after the date hereof, regardless of any general incorporation langua…