Recession
A recession is a significant, widespread, and prolonged downturn in economic activity, officially declared in the United States by the National Bureau of Economic Research (NBER) based on a range of indicators including GDP, employment, industrial production, and retail sales.
The popular rule of thumb — two consecutive quarters of negative real GDP — is a useful shorthand but not the NBER's official definition. The NBER's Business Cycle Dating Committee looks for a 'significant decline in economic activity that is spread across the economy and lasts more than a few months.' This explains why the COVID-19 recession of February–April 2020 was only two months long (making it the shortest in U.S. history) yet was officially designated a recession: the magnitude and breadth of the contraction were unmistakable even though the timeline was brief.
Recessions are deeply damaging to households. Unemployment rises (sometimes sharply), consumer and business confidence collapses, credit tightens as banks become risk-averse, housing prices often decline, and equity markets typically fall. The average post-World War II U.S. recession lasted about 10 months and saw unemployment rise by roughly 3 percentage points. The Great Recession (December 2007 to June 2009) was the worst in the post-war era, lasting 18 months and destroying 8.7 million jobs.
For equity investors, recessions are historically associated with bear markets — peak-to-trough declines of 20% or more in broad indices. The S&P 500 fell about 57% from its October 2007 peak to its March 2009 trough during the Great Recession, and about 34% during the COVID-19 crash (though it recovered within months). However, since markets are forward-looking, they typically bottom well before the economy does — often 3–6 months before the NBER officially calls the end of a recession. Missing the early stages of a recovery by waiting for 'all-clear' economic signals is a costly mistake for investors.
The inverted yield curve, the Conference Board's Leading Economic Indicators index, and the ISM Manufacturing PMI (below 50) are among the most reliable early-warning signs of recession risk. Rising credit spreads in the corporate bond market — as investors demand more compensation for default risk — also tend to precede recessions. Monitoring a basket of these indicators, rather than any single signal, gives the most reliable assessment of recession probability.