The Institute for Supply Management released its manufacturing purchasing managers' index for the U.S. on Wednesday. The index rose to 51.3 in May from 50.8 in April. Analysts had expected the index to decrease to 50.2.

A reading above 50 indicates expansion, below indicates contraction.

The increase was mainly driven by rises in prices and supplier deliveries. The price index jumped to 63.5 in May from 59.0 in April, while supplier deliveries climbed 54.1 from 49.1.

The production index dropped to 52.6 in May from 54.2 in April, while the new orders index fell to 55.7 from 55.8.

The employment index remained unchanged at 49.2 in May.