The Federal Reserve Bank of Chicago's national activity index, which measures economic activity in the U.S., fell in November. The three-month average of the index slipped to -2.49 from October's reading of -2.40.

"This negative value suggests that growth in national economic activity was well below its historical trend," according to the Chicago Fed's report.

A reading of zero indicates the economy is expanding at its historical rate of growth. Negative readings indicate below-average growth. And readings of below -0.70 following a period of economic expansion indicate an increasing likelihood of recession. The measure first indicated an increasing likelihood of recession in December 2007, according to the Chicago Fed; and the National Bureau of Economic Research has since announced that the U.S.' business cycle peaked in that month.

The national activity index is a weighted average of 85 indicators of economic activity.