And, as many already suspected, it started a year ago:
The Business Cycle Dating Committee of the National Bureau of Economic Research met by conference call on Friday, November 28. The committee maintains a chronology of the beginning and ending dates (months and quarters) of U.S. recessions. The committee determined that a peak in economic activity occurred in the U.S. economy in December 2007. The peak marks the end of the expansion that began in November 2001 and the beginning of a recession. The expansion lasted 73 months; the previous expansion of the 1990s lasted 120 months.
The Times suggests this wasn't the reason for today's sell-off on Wall Street:
The announcement came as the stock market fell sharply, its first decline in five sessions. The Dow Jones industrial average was off more than 440 points by early afternoon. The Standard & Poor’s 500-stock index fell nearly 6 percent.
Analysts said that after last week’s gains — the biggest five-day rally in decades — a sell-off was to be expected.
"You had the biggest weekly gain in 30, 35 years," said Anthony Conroy, head equity trader at BNY ConvergEx Group. "Some profit-taking is warranted."
...
Monday brought its own share of poor economic news. The manufacturing industry suffered its worst month since 1982, according to a closely watched index published by the private Institution for Supply Management. The index fell to 36.2 in November from 38.9 in October, on a scale where readings below 50 indicate contraction.
That was the worst monthly reading since 1982, and a sign that the worldwide credit crisis was taking a serious toll on American businesses. New orders fell sharply, although export orders held steady from October.
A separate report from the Commerce Department showed that spending on construction projects fell 1.2 percent in October, after staying unchanged in September. Private construction dropped 2 percent with a sharp drop in the residential sector, offering few signs of relief from the housing slump.
More good times.