Markit Economics released its preliminary services purchasing managers' index (PMI) for the U.S. on Friday. The U.S. preliminary services purchasing managers' index (PMI) declined to 55.6 in September from 56.1 in August, in line with expectations.

A reading above 50 indicates expansion in economic activity.

The decline was driven by a slowdown in new business growth and a drop in input price inflation.

"The survey data point to sustained steady expansion of the US economy at the end of the third quarter, but various warning lights are now flashing brighter, meaning growth may continue to weaken in coming months. Although the surveys suggest the economy expanded at a 2.2% annualised rate in the third quarter, growth slowed in September and could weaken further in coming months," Markit Chief Economist Chris Williamson.