PMI stands for Purchasing Managers' Index. The official name of this report, however, is the ISM - Chicago. ISM is an acronym for Institute for Supply Management. This report is released monthly on the last business day of the month. The report is released to private subscribers three minutes before it is released to the public. Datat in the report pertains to the same month that the report is released in. January data is release on the last business day of Januray. This report is not revised in subsequent months.

Kingsbury International (on behalf of the Institute for Supply Management (Chicago)) conduct a survery of both manufacturing and non-manufacturing firms in the Chicago area. A composite diffusion index is compiled from this survey. A value over 50 percent is indicative of an expanding business sector.

The overall index that is produced by the survey is called the Business Barometer which investors usually refer to as the Chicago PMI. The figure shows acceleration with a value of 50% showing zero acceleration. A figure above 50% indicates expansion and a figure below contraction. The further that the figure is away from 50% the faster the acceleration.