The U.S. service sector expanded in May, but at a slightly slower pace than in April, according to the Institute for Supply Management's nonmanufacturing index released today. The index slipped to 51.7 from 52.0 in April. Index readings above 50 indicate growth.

Employment in the service sector, however, contracted in May. The employment portion of the index fell to 48.7 from 50.8 in April.

The report is based on a survey of purchasing and supply executives across the country.