But Grillo, swarmed by reporters outside his villa in Genoa, said his forces would seek to thwart any Bersani-Berlusconi deal. Raising the specter of early elections, he predicted any such coalition will "last seven, eight months. The economy won't let them escape."
Investors around the world appeared skeptical over the prospects of a deal.
"Clearly markets are taking fright from the messy and chaotic Italian election result," said Louise Cooper, financial analyst at CooperCity.
Italy is hugely important for the future of the euro, and its apparent stability over the past six months has been one of the reasons that concerns over the currency have eased. Of the 17 European Union countries that use the euro, Italy has the second-highest debt burden as a proportion of its gross domestic product, at 127 percent. Only Greece's is higher. Italy has to spend around €80 billion a year just to service its debt.
The worry across in financial markets is that Italy's appetite for reform may wane and its debt situation may deteriorate. Though Italy's annual borrowing — its budget deficit — is relatively small compared with other euro countries at 3 percent of its annual gross domestic product, its overall debt stands at a colossal €2 trillion.