Markit Economics released its preliminary manufacturing purchasing managers' index (PMI) for the U.S. on Monday. The U.S. preliminary manufacturing purchasing managers' index (PMI) fell to 50.5 in May from 50.8 in April, missing expectations for an increase to 51.0. It was the lowest level since September 2009.

A reading above 50 indicates expansion in economic activity.

The decline was driven by a fall in output and a softer pace of expansion in new business.

"The weak manufacturing PMI data cast doubt on the ability of the US economy to rebound from its disappointing start to the year in the second quarter," Markit Chief Economist Chris Williamson said.

"The survey is signalling that manufacturing will act as a drag on economic growth in the second quarter, leaving the economy once again dependent on the service sector, and consumers in particular, to sustain growth," he added.