The index measures where the overall U.S. economy is headed in the next three to six months. It stood at 100 in 1996, its base year. July's decline was the third time in the last four months that the indicators index failed to increase.
Contributing most to last month's decline were stock prices, the Conference Board said.
The coincident index, which measures current economic activity, rose 0.1 percent in July to 115.0. The index of lagging indicators, which reflects changes that have already occurred, rose 0.1 percent last month to 100.7.