Washington ? The Greek debt crisis sent a shudder through global financial markets and served as a reminder of how vulnerable the world economy remains to the threat of a financial panic.

To many, market developments this week served as a spooky reminder of the fall of 2008 and the panic after Lehman Brothers collapsed in September 2008.

“If people get scared that Greece could default, they are going to be scared that Portugal will default and then other countries. Once people panic, they panic about everything,” said David Wyss, chief economist at Standard and Poor’s in New York.

European and Germany officials have sought to assure investors that they were working quickly to approve a bailout for Greece with European Union monetary affairs commission Olli Rehn, saying he was confident that talks on a bailout package of support from European countries and the International Monetary Fund would be wrapped up in a few days.

The White House released a statement late Wednesday that President Barack Obama and German Chancellor Angela Merkel had discussed the “importance of resolute action by Greece and timely support from the IMF and Europe to address Greece’s economic difficulties.”

In Asia, while there are not yet significant concerns about the governments’ creditworthiness, big economies like China and Japan still have much at stake. Europe is an important export market for Asia, and China and Japan are among the biggest investors in the debt issued by the United States and European countries with holdings worth billions of dollars.

There are also concerns the turmoil in Europe could convince China to delay any appreciation of its currency — widely viewed as undervalued — aggravating tensions with the U.S. and other trading partners.

Economists noted that the debt problems in Greece and other European countries often occur after a financial crisis. Governments borrow heavily to prop up their banking systems, which sends their debt burdens soaring.

The United States has seen its publicly held debt jump from 36 percent of the total economy in 2007 to 64 percent this year. That’s the highest level since 1951, when the country was paying off the debt run up to fight World War II.

Debt levels of all developing countries are rising to levels not seen over the past 60 years, the IMF said in an economic survey released last week.

“Governments used their resources to end the financial panic and the Great Recession,” said Mark Zandi, chief economist at Moody’s Analytics, “but now they have to figure out how to pay for it.”