A worker at the Aluminum Case Company in Chicago.
Tim Boyle | Bloomberg | Getty Images
The Chicago Purchasing Managers Index showed surprising weakness in September, with the gauge dropping below 50.
Chicago PMI, a reading on manufacturing activity, fell to 48.7, compared with expectations of 53.0 and down sharply from 54.4 reported a month earlier.
A reading below 50.0 indicates a contraction in the sector.
