CMB, owned by the Saverys family, and affiliates together hold 88.61% of the outstanding shares in Euronav, which exceeds the maximum allowed for the index.
"The Bel 20 rulebook prescribes that should the acquiring party own more than 85% of the shares, the company being acquired will exit the index," Euronext said.
Belgium's Euronav announced in October that its two major shareholders, CMB and Frontline, had reached a deal that would see the Saverys family take control of the oil tanker company and buy its remaining shares.
Euronav, which had debuted on the index on Monday, will exit it as of Wednesday morning, Euronext said.
(Reporting by Diana Mandiá; Editing by Mark Potter)