The Institute for Supply Management released its manufacturing purchasing managers' index for the U.S. on Friday. The index remained unchanged at 51.5 in April, missing expectations for a rise to 52.0.

March's figure was revised up from 51.3.

A reading above 50 indicates expansion, below indicates contraction.

The new orders index increased to 53.5 in April from 51.8 in March.

The production index increased to 56.0 in April from 53.8 in March.

The employment index decreased to 48.3 in April from 50.0 in March.