Abivax announces trading resumption of its ordinary shares on Euronext Paris

PARIS, France, July 1, 2026 – 02:35 p.m. CEST – Abivax SA (Euronext Paris: FR0012333284 – ABVX) (“Abivax” or the “Company”), a clinical-stage biotechnology company focused on developing therapeutics that harness the body’s natural regulatory mechanisms to stabilize the immune response in patients with chronic inflammatory diseases, announced the trading resumption of its ordinary shares on the regulated market of Euronext Paris as from 3:30 p.m. CEST. Trading of the ordinary shares of the Company was halted at the request of the Company on July 1, 2026 from 9:00 a.m. CEST in the context of the previously announced public offering by the Company of its American Depositary Shares, each representing one ordinary share, €0.01 nominal value per share, of the Company, in the United States (the “Offering”), in order to allow for the confirmation of allocations to investors and the announcement of the pricing of the Offering. *** About Abivax Abivax is a clinical-stage biotechnology company focused on developing therapeutics that harness the body’s natural regulatory mechanisms to stabilize the immune response in patients with chronic inflammatory diseases. Based in France and the United States, Abivax’s lead drug candidate, obefazimod (ABX464), is in Phase 3 clinical trials for the treatment of moderately to severely active ulcerative colitis. Contacts:

Abivax Investor Relations Patrick Malloy patrick.malloy@abivax.com +1 847 987 4878

*** Disclaimer This press release does not constitute an offer to sell or the solicitation of an offer to buy any securities of the Company, nor shall there be any sale of such securities, in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.