X0202 SCHEDULE 13G/A 0002005369 XXXXXXXX LIVE 2 Ordinary Shares, nominal value Euro 0.01 per share 06/30/2026 0001956827 Abivax S.A. 00370M103 7 BD HAUSSMANN PARIS I0 75009 Rule 13d-1(c) Invus Public Equities, L.P. D0 4790187.00 0.00 4790187.00 0.00 4790187.00 N 6.0 PN Invus Public Equities, L.P. holds an aggregate of 4,249,759 Ordinary Shares, nominal value Euro 0.01 per share (the "Shares"), and 540,428 American Depositary Shares ("ADSs"), each of which ADS represents one Share of Abivax S.A. (the "Issuer"). Invus Public Equities Advisors, LLC DE 4790187.00 0.00 4790187.00 0.00 4790187.00 N 6.0 OO Invus Public Equities, L.P. holds an aggregate of 4,249,759 Ordinary Shares, nominal value Euro 0.01 per share (the "Shares"), and 540,428 American Depositary Shares ("ADSs"), each of which ADS represents one Share of Abivax S.A. (the "Issuer"). Invus Global Management, LLC DE 4790187.00 0.00 4790187.00 0.00 4790187.00 N 6.0 OO Invus Public Equities, L.P. holds an aggregate of 4,249,759 Ordinary Shares, nominal value Euro 0.01 per share (the "Shares"), and 540,428 American Depositary Shares ("ADSs"), each of which ADS represents one Share of Abivax S.A. (the "Issuer"). Siren, L.L.C. DE 4790187.00 0.00 4790187.00 0.00 4790187.00 N 6.0 OO Invus Public Equities, L.P. holds an aggregate of 4,249,759 Ordinary Shares, nominal value Euro 0.01 per share (the "Shares"), and 540,428 American Depositary Shares ("ADSs"), each of which ADS represents one Share of Abivax S.A. (the "Issuer"). Avicenna Life Sci Master Fund LP E9 35572.00 0.00 35572.00 0.00 35572.00 N 0.0 PN Avicenna Life Sci Master Fund LP holds an aggregate of 35,572 American Depositary Shares ("ADSs"), each of which ADS represents one Ordinary Share, nominal value Euro 0.01 per share (the "Shares"), of Abivax S.A. (the "Issuer"). Avicenna Life Sci Master GP LLC DE 35572.00 0.00 35572.00 0.00 35572.00 N 0.0 OO Avicenna Life Sci Master Fund LP holds an aggregate of 35,572 American Depositary Shares ("ADSs"), each of which ADS represents one Ordinary Share, nominal value Euro 0.01 per share (the "Shares"), of Abivax S.A. (the "Issuer"). Ulys, L.L.C. DE 35572.00 0.00 35572.00 0.00 35572.00 N 0.0 OO Avicenna Life Sci Master Fund LP holds an aggregate of 35,572 American Depositary Shares ("ADSs"), each of which ADS represents one Ordinary Share, nominal value Euro 0.01 per share (the "Shares"), of Abivax S.A. (the "Issuer"). Raymond Debbane R1 4825759.00 0.00 4825759.00 0.00 4825759.00 N 6.0 IN Invus Public Equities, L.P. holds an aggregate of 4,249,759 Ordinary Shares, nominal value Euro 0.01 per share (the "Shares"), and 540,428 American Depositary Shares ("ADSs"), and Avicenna Life Sci Master Fund LP holds an aggregate of 35,572 ADSs, each of which ADS represents one Share of Abivax S.A. (the "Issuer"). Abivax S.A. 7-11 boulevard Haussmann, 75009 Paris, France See Item 2(c) below. See Item 2(c) below. (i) Invus Public Equities, L.P. ("Invus Public Equities") 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Bermuda limited partnership (ii) Invus Public Equities Advisors, LLC ("Invus PE Advisors") 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Delaware limited liability company (iii) Invus Global Management, LLC ("Global Management") 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Delaware limited liability company (iv) Siren, L.L.C. ("Siren") c/o The Invus Group, LLC, 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Delaware limited liability company (v) Avicenna Life Sci Master Fund LP ("Avicenna Fund") 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Cayman Islands limited partnership (vi) Avicenna Life Sci Master GP LLC ("Avicenna GP") 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Delaware limited liability company (vii) Ulys, L.L.C. ("Ulys") 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Delaware limited liability company (viii) Mr. Raymond Debbane 750 Lexington Avenue, 30th Floor, New York, NY 10022 Citizenship: Panama The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons." Y As of June 30, 2026, Invus Public Equities beneficially held 4,790,187 Ordinary Shares, nominal value Euro 0.01 per share (the "Shares") of Abivax S.A. (the "Issuer"), represented by (i) 4,249,759 Shares and (ii) 540,428 American Depositary Shares ("ADSs") directly held by Invus Public Equities, and Avicenna Fund directly held 35,572 ADSs. Each ADS represents one Share. Invus PE Advisors, as the general partner of Invus Public Equities, controls Invus Public Equities and, accordingly, may be deemed to beneficially own the Shares beneficially held by Invus Public Equities. Global Management, as the managing member of Invus PE Advisors, controls Invus PE Advisors and, accordingly, may be deemed to beneficially own the Shares that Invus PE Advisors may be deemed to beneficially own. Siren, as the managing member of Global Management, controls Global Management and, accordingly, may be deemed to beneficially own the Shares that Global Management may be deemed to beneficially own. Avicenna GP, as the general partner of Avicenna Fund, controls Avicenna Fund and, accordingly, may be deemed to beneficially own the Shares beneficially held by Avicenna Fund. Ulys, as the managing member of Avicenna GP, controls Avicenna GP and, accordingly, may be deemed to beneficially own the Shares that Avicenna GP may be deemed to beneficially own. Mr. Raymond Debbane, as the managing member of Siren and Ulys, controls Siren and Ulys and, accordingly, may be deemed to beneficially own the Shares that Siren and Ulys may be deemed to beneficially own. As of June 30, 2026, each of the Reporting Persons may be deemed to be the beneficial owner of the Shares listed on such Reporting Person's cover page. Calculations of the percentage of Shares beneficially owned are based on 79,800,669 Shares outstanding as of June 26, 2026, as reported in the Issuer's Form 424(b)(5) filed with the Securities and Exchange Commission on July 2, 2026. See each cover page hereof. See each cover page hereof. See each cover page hereof. See each cover page hereof. Y Y Y Y Y N Each of the Reporting Persons hereby makes the following certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11. Invus Public Equities, L.P. /s/ Raymond Debbane 08/13/2026 Invus Public Equities Advisors, LLC /s/ Raymond Debbane 08/13/2026 Invus Global Management, LLC /s/ Raymond Debbane 08/13/2026 Siren, L.L.C. /s/ Raymond Debbane 08/13/2026 Avicenna Life Sci Master Fund LP /s/ Raymond Debbane 08/13/2026 Avicenna Life Sci Master GP LLC /s/ Raymond Debbane 08/13/2026 Ulys, L.L.C. /s/ Raymond Debbane 08/13/2026 Raymond Debbane /s/ Raymond Debbane 08/13/2026