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 56.4 in May from 57.4 in April, missing expectations for a decrease to 57.0.

A reading above 50 indicates expansion in economic activity.

The decline was driven by a decrease in new business growth. The preliminary new business index declined to 55.8 in May from 57.7 in April.

"The rate of expansion remains below the buoyant rates seen throughout much of last year, as slower growth of service activity has been accompanied by a slowdown in the manufacturing sector, which has seen exporters hit by the stronger dollar," Markit Chief Economist Chris Williamson.