Mont-Saint-Guibert, Belgium, December 20, 2023, 10:01 p.m. CET – regulated information – Celyad Oncology SA (Euronext: CYAD) (“Celyad Oncology” or the “Company”), announces today, in accordance with article 14 of the Belgian law of May 2, 2007 relating to the publication of significant participations in issuers whose shares are admitted to trading on a regulated market (the “Transparency Law”), having received a transparency notification dated December 19, 2023 indicating that CFIP CLYD (UK) Limited, a subsidiary of Fortress Investment Group LLC, has crossed the statutory threshold of 55%, holding 29,358,654 voting rights, or 58.37% of the voting rights of Celyad Oncology.