Mediobanca SpA’s chief executive officer said a takeover attempt by smaller rival Banca Monte dei Paschi di Siena SpA was unsolicited, as the Italian investment bank prepared to respond and possibly defend itself.

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.

Shares in Italy's Monte dei Paschi (MPS) fell at market open on Monday, extending Friday's losses, after the state-backed lender launched a surprise 13.3-billion-euro ($13.9 billion) bid for merchant bank Mediobanca.