The Institute for Supply Management released its manufacturing purchasing managers' index for the U.S. on Tuesday. The index declined to 51.1 in August from 52.7 in July, missing expectations for a fall to 52.6. It was the lowest level since May of 2013.

A reading above 50 indicates expansion, below indicates contraction.

The decline was partly driven by a fall in new orders. The new orders index dropped to 51.7 in August from 56.5 in July.

The employment index was down to 51.2 in August from 52.7 in July.

The production index declined to 53.6 in August from 56.0 in July.

The price index declined to 39.0 in August from 44.0 in July.