The national activity index was within the range of expectations in September at 0.02, up from minus 0.22 in August, which was revised down from minus 0.16. The 3-month average was at zero after minus 0.14 the previous month. Readings point to economic growth close to historical trends.

All four categories improved in September, although only two made a positive contribution: production and income at 0.03, up from minus 0.01 in August, and employment-related indicators at 0.01. By contrast, personal consumption and housing, and sales-related indicators both made a negative contribution of minus 0.01, each improving from minus 0.06.

The national activity index is expected to rise to plus 0.05 in September versus a lower-than-expected minus 0.16 in August.

The Chicago Fed National Activity Index (CFNAI) is a monthly index that tracks overall economic activity and inflationary pressures. 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 over time, a positive index reading corresponds to growth above trend and a negative index reading corresponds to growth below trend.

This index is unique among regional Federal Reserve Bank indexes in that it is national in scope. Investors are eager to have insight into economic growth and inflation. This index combines 85 diverse and already released indicators from four broad categories -- production and income; employment, unemployment, and hours; personal consumption and housing; and sales, orders, and inventories -- into an overall index to measure economic performance. The index provides another measure with which investors can measure overall growth.