Markit Economics released its preliminary services purchasing managers' index (PMI) for the U.S. on Tuesday. The U.S. preliminary services purchasing managers' index (PMI) declined to 54.4 in October from 55.1 in September. It was the lowest level since January.

Analysts had expected the index to remain unchanged at 55.1.

A reading above 50 indicates expansion in economic activity.

The decline was driven by a slowdown in new business growth and a weaker employment growth.

"Combined with the manufacturing results released last week, the services PMI survey indicates that the pace of economic growth slowed in October to the weakest since January, when business was hit by extreme weather," Markit Chief Economist Chris Williamson.

He added that the figures suggest that the U.S. economy was expanding at an annual rate of 1.8% at the beginning of the fourth quarter.