A gauge of future U.S. economic activity tumbled for a 10th straight month in December with a widespread weakening outlook for manufacturing, home building and both job and financial markets.

The Conference Board Monday said its Leading Economic Index slid 1.0% in December following a downwardly revised decline of 1.1% in November. The decline exceeded all 22 forecasts in a poll of economists by Reuters, which had a median expectation of a decline of 0.7%.

"The U.S. LEI fell sharply again in December - continuing to signal recession for the U.S. economy in the near term," Ataman Ozyildirim, the Conference Board's senior director for economics, said in a statement.