"With a 28-point plunge in [weekly leading index] growth since October we're clearly seeing a downturn in forward-looking data that has inevitably been followed by a slowdown in overall U.S. economic growth," said Lakshman Achuthan, managing director of the institute.

In the weekly period ending May 28, the weekly leading index level fell to 124.1 from the prior period's reading of 125.6. The index's growth rate fell to 0.4% from 5.1% in the prior period.

The growth rate is derived from a four-week average of the levels that is compared against the previous year's average.