The last time Banca Monte dei Paschi di Siena SpA bought another lender, it was the beginning of the road to collapse and nationalization.Most Read from BloombergWhat Happened to Hanging Out on the Street?

The surprise move is the latest amid a wave of consolidation in the country’s banking industry in recent months and would create Italy’s third-largest entity in the sector.

The deal intensifies with MPS offering 23 of its shares for every 10 shares of Mediobanca, representing a 5% premium over the last closing price.