The Conference Board's measure of leading indicators decreased by 0.1% in August, compared with the expectations for a 0.1% increase in a survey compiled by Bloomberg and following a 0.2% increase in July.
This is the first monthly decline since March.
There were negative contributions from four of the 10 components, with a decline in business conditions expectations the largest factor.
The Conference Board said that the six-month growth rate has turned negative due to the August decline, while growth rate is expected to slow in the near future.