Interbrew is set to join Bel20, the index of Belgium's 20 largest companies, despite the shares currently trading below the issue price at which they floated less than two months ago.

The Belgian brewing company raised €2.9bn ($2.73bn) in November last year in the largest initial public offering on Euronext Brussels. Euronext is a pan-European market formed from the merger of the Brussels, Paris and Amsterdam exchanges in September last year. It enters Bel20, the Euronext Brussels index which is widely used locally as a benchmark for investment performance, on 1 February..