The Chicago Fed National Activity Index was −2.57 in September, down from −1.61 in August. Most of the index's decline in September was driven by the steep drop in industrial production, as reflected in the contribution of the production and income category of indicators. However, all four broad categories of indicators made negative contributions to the index in September.
The CFNAI is a weighted average of 85 existing monthly indicators of national economic activity. It is constructed to have an average value of zero and a standard deviation of one. Since economic activity tends toward trend growth rate over time, a positive index reading corresponds to growth above trend and a negative index reading corresponds to growth below trend.