Banca Popolare di Lodi has disclosed it has more than doubled its stake in Banca Antonveneta in a month. Consob, the Italian regulator, yesterday launched an investigation into Antonveneta shareholdings.

Lodi declared a 10.8% stake in Antonveneta, the Italian bank at the centre of a proposed €6.3m ($8.1bn) takeover bid by ABN Amro. On March 9 it owned 4.98%.