The Thomson Reuters/University of Michigan preliminary consumer sentiment index slid to 85.7 in September from a final reading of 91.9 in August, missing expectations for a decrease to 91.2. It was the lowest level since September 2014.

"Consumers still anticipate a weaker domestic economy due to the global slowdown and are less optimistic about future growth in jobs and wages than they were a few months ago," the Surveys of Consumers chief economist at the University of Michigan Richard Curtin said.

The decline in the index was mainly driven by falls in the index of current economic conditions and the index of consumer expectations.

The index of current economic conditions declined to 100.3 in September from 105.1 in August, while the index of consumer expectations decreased to 76.4 from 83.4.

The one-year inflation expectations rose to 2.9% in September from 2.8% in August.