The University of Michigan’s consumer sentiment index fell to 90.2 in August from 90.9 in July. Economists had expected a reading of 91.

The closely watched measure of consumer confidence in the United States fell in August, according to a published report Tuesday.

“While it’s a bit of a surprise, the slightly downbeat news on confidence can be explained by the ongoing weakness in employment, and perhaps consumers are a little concerned about the backup in mortgage rates,” said Douglas Porter, senior economist at BMO Nesbitt Burns. “But while they’re becoming less confident, they’re still buying — the latest sales numbers still look good.”

In the university’s report, available only to paying subscribers, the “current conditions” component of the index, which measures how consumers feel about their present situation, rose to 100.5 from 94.7.

The “expectations” component of the index, which measures how consumers think the economy will perform in the next 12 months, was flat at 83.6, matching July’s level, according to the report.