U.S. consumer sentiment dipped in August, led by Americans' worsening expectations for the future as corporate layoffs pile higher and the stock market weakens, market sources said a Friday report showed.

The University of Michigan's August consumer sentiment index, which is released directly to subscribers only, dipped to 91.5 from 92.4 in July, sources said. Economists had forecast the index to read 93.2. The preliminary reading, released mid-month, was 93.5. 

The current conditions index, a gauge of how comfortable American consumers feel about present economic conditions, rose to 101.2 in August from 98.6 in July. That number was down slightly from a preliminary figure of 101.7. 

The expectations gauge of the index, which measures consumers' attitudes about the year ahead, fell sharply to 85.2 in August from 88.4 in July. The preliminary reading was 88.3. 

The main index tracked the direction of the Conference Board's barometer of consumer confidence, which also fell in August. But the drop in that measure, released on Tuesday, was led by a more pessimistic assessment of the present situation. That report rattled financial markets around the globe on worries U.S. consumer spending growth could slow in months ahead.