The Chicago Federal Reserve Bank's monthly National Activity Index fell to a reading of minus 0.08 in July from 0.06 in June compared with expectations for a smaller decrease to minus 0.05 in a Bloomberg survey.
The three-month moving average fell to minus 0.04 from 0.01.
Of the 85 individual indicators, 40 made positive contributions to the index in July, while 45 made negative contributions. Some 37 indicators improved in the month, while 48 indicators deteriorated.