Cambridge, Massachusetts based National Bureau of Economic Research, a private, nonprofit group of economists, said on Monday that U.S. has been in a recession since December 2007. The committee identified December 2007 as the peak month, after determining that the subsequent decline in economic activity was large enough to qualify as a recession.

The NBER announced that December 2007 marked the end of a 73 month expansion in US. The previous cycle of economic expansion, which ended in 2001, lasted 120 months or 10 years.

The report said "because a recession is a broad contraction of the economy, not confined to one sector, the committee emphasizes economy-wide measures of economic activity. The committee believes that domestic production and employment are the primary conceptual measures of economic activity."

"The committee views the payroll employment measure, which is based on a large survey of employers, as the most reliable comprehensive estimate of employment. This series reached a peak in December 2007 and has declined every month since then."

According to traditional view, an economy is said to be in recession if it suffers two consecutive quarters of negative growth. However, the committee's defines recession as "a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in production, employment, real income, and other indicators."

A report last week showed U.S. economy contracted at an annual rate of 0.5% in the third quarter after expanding 2.8 percent in the second quarter. The economy has lost 1.2 million jobs in the first 10 months of this year.

Commenting on NBER's report, White House spokesman Tony Fratto said "the most important things we can do for the economy right now are to return the financial and credit markets to normal, and to continue to make progress in housing, and that's where we'll continue to focus."

US Stocks were trading deep in red in afternoon session. At 1:36 pm ET, Dow Jones Industrial Average shed 403.49 points or 4.57% to 8,425.55. Nasdaq Composite shrank 86.99 points or 5.66% while S&P 500 slipped 49 points or 5.47%.