Chicago-area business activity unexpectedly expanded at a faster rate in the month of July, according to a report released by the Institute for Supply Management - Chicago on Tuesday. The ISM Chicago said its business barometer rose to 53.7 in July from 52.9 in June, with a reading above 50 indicating an increase in business activity. The modest increase by the business barometer came as a surprise to economists, who had expected the index to edge down to 52.5.