Chicago Fed National Activity Index
A weighted average of 85 monthly US series; zero is trend growth, and a three-month average below −0.70 has marked every recession since 1967.
The CFNAI is the first principal component of 85 series covering production, employment, consumption and sales, published monthly by the Federal Reserve Bank of Chicago. Zero means the economy is growing at its historical trend; negative values mean below-trend growth.
The Chicago Fed's own rule uses the three-month moving average: below −0.70 after a period of expansion signals a recession has begun, and above +0.70 more than two years into an expansion signals rising inflation risk.