You don’t have to be Italian to be worried about the repercussions.

Financial crises tend to arrive every decade or so, and Italy is near the top of a list of flash points that could touch off the next one, alongside Turkey’s economic and political turmoil, President Trump’s trade war, Britain’s exit from the European Union and a broad slowdown in global growth.

But in contrast to the financial crisis that began in 2008, central banks may not be able to come to the rescue this time, said Richard Portes, a professor of economics at London Business School. They used up much of their crisis fighting tools coping with the last meltdown.

“It would be very difficult for Mario Draghi to think of another way to get out of the mess,” Mr. Portes said, referring to the president of the European Central Bank.

That is why investors are so worried about Italy. The eurozone is still recovering from a debt crisis that began in Greece in 2010. Italy, the currency bloc’s third-largest economy, accounts for 11 percent of the European Union’s gross domestic product — 10 times as much as Greece — and has the potential to create far more damage.