A day after Prime Minister Silvio Berlusconi offered his resignation in the face of rising global market skepticism, investors revolted Wednesday, suggesting they do not believe that even a new leadership could fix Italy’s intransigent financial problems and revive its economy.

Italian bond rates crossed a crucial level of 7 percent, prompting questions about whether Italy could soon need an international bailout just as the financially strapped nations of Greece, Ireland and Portugal did before it.

The difference this time is that Italy, the third largest economy in the euro zone, is on a different scale than those other, much smaller European nations. That means any bailout would have to be proportionately far larger, and some analysts question whether the European Union or the International Monetary Fund have enough resources to pay for it at all.

“This is a new phase of the crisis,” said Nicolas Veron, a senior fellow at Bruegel, a research organization in Brussels. “This is uncharted territory.”