The bank will canvass institutional investor interest through Thursday, while the offer for retail investors will end on Wednesday. As the lender didn't provide terms of the offer, the price and total number of shares to be sold will be determined based on investor demand and on the outcome of the separate debt-to-equity swap which started last week.

The bank's CEO Marco Morelli, who took over in September, is scrambling to find financial backers in his effort to clean up the bank's balance sheet which continues to corrode under the weight of rising non-performing loans. A failure to recatpialize the bank would be a blow to Italy's sputtering efforts to revive a banking industry that's burdened with about €360 billion in troubled loans, dragging down the economy by limiting lending.