Tanker company Euronav will exit Belgium's blue-chip Bel-20 index after just two days of trading, as it no longer meets the membership conditions after its takeover by Compagnie Maritime Belge (CMB), bourse operator Euronext said on Tuesday.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.