But on Thursday, the market moved swiftly in the other direction.
The Dow Jones Industrial Average hit its highest mark since December 2007, and the Standard & Poor's 500 index soared to its highest level since January 2008 in a rally that seemed destined to mark a milestone: American stocks have come almost all the way back.
A long-anticipated plan to support struggling countries in the European Union provided the necessary jolt, and the gains were extraordinarily broad.
"There's just a sea of green," said JJ Kinahan, TD Ameritrade's chief derivatives strategist. "It's pretty fun."
At the start of 2008, the U.S. economy was already a month into recession, though most people scarcely knew it at the time. The S&P had recently hit an all-time high, and the unemployment rate was 5%, compared with the current 8.3%.
Then, in March 2008, the investment bank Bear Stearns collapsed under the weight of bad mortgage bets, and investors began to sell.
In September, the full financial crisis took hold as Lehman Brothers filed for bankruptcy, banks stopped lending to each other and investors began dumping stocks in earnest.
By March 2009, the S&P had dropped 57% from its high to hit a 12-year low of 676.
Since then, the index has been on an impressive if often bumpy climb.
Helping to power it was unprecedented support from the Federal Reserve, which critics say has reignited a dangerous gambling spirit among professional investors, and record profits at big U.S. companies.
Although stocks have rebounded, the broader economy is still lagging. But Barry Knapp, head of U.S. equity strategy at Barclays Capital, said stocks tend to anticipate the future economy rather than reflecting current conditions.
"It can be a misleading forecasting tool, but sometimes it's telling you something significant," he said. "It's entirely possible the stock market is telling us that there is a better economic environment out there."
So could the rally help President Barack Obama?
A number of recent studies have connected a rising stock market to improved odds of re-election for the incumbent president.
Since 1900, when the S&P 500 has posted gains from July to October in an election year, voters returned the sitting president to the White House 80% of the time, according to a study by S&P Capital IQ.
The S&P 500 index jumped 28.68 points to 1,432.12. The Dow Jones surged 244.52 points to 13,292.
The Nasdaq composite index also reached a milestone, gaining 66.54 points to close at 3,135.81, its highest level in 12 years.