Markit Economics released its final services purchasing managers' index (PMI) for the U.S. on Wednesday. The final U.S. services PMI declined to 56.2 in May from 57.4 in April, down from the preliminary reading of 56.4.

A reading over 50 indicates expansion in the sector.

The downward revision was driven by weaker than previously estimated new business index, which decreased to 55.7 in May from 57.7 in April, down from the preliminary reading of 55.8.

"Slowing service sector growth adds to signs that the U.S. economy has lost some momentum after an initial bounce-back from weather-related weakness at the start of the year," Markit Economics Chief Economist Chris Williamson noted.