Business cycle

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Macroeconomics
Basic concepts Aggregate demand Aggregate supply Business cycle CAGR Deflation Demand shock Disinflation Effective demand Expectations Adaptive Rational Financial crisis Growth Inflation Demand-pull Cost-push Interest rate Investment Liquidity trap Measures of national income and output GDP GNI NNI Microfoundations Money Endogenous Money creation Demand for money Liquidity preference Money supply National accounts SNA Nominal rigidity Price level Recession Shrinkflation Stagflation Supply shock Saving Unemployment
Policies Fiscal Monetary Commercial Central bank Universal basic income
Models IS–LM AD–AS Keynesian cross Multiplier Accelerator Phillips curve Arrow–Debreu Harrod–DomarНмиф Solow–Swan Ramsey–Cass–Koopmans Overlapping generations General equilibrium DSGE Endogenous growth Matching theory Mundell–Fleming Overshooting NAIRU
Related fields Econometrics Economic statistics Monetary economics Development economics International economics
Schools Mainstream Keynesian Neo- New Monetarism New classical Real business-cycle theory Stockholm Supply-side New neoclassical synthesis Saltwater and freshwater Heterodox Austrian Chartalism Modern monetary theory Ecological Post-Keynesian Circuitism Disequilibrium Marxian Market monetarism
People François Quesnay Adam Smith Thomas Robert Malthus Karl Marx Léon Walras Knut Wicksell Irving Fisher Wesley Clair Mitchell John Maynard Keynes Alvin Hansen Michał Kalecki Gunnar Myrdal Simon Kuznets Joan Robinson Friedrich Hayek John Hicks Richard Stone Hyman Minsky Milton Friedman Paul Samuelson Lawrence Klein Edmund Phelps Robert Lucas Jr. Edward C. Prescott Peter Diamond William Nordhaus Joseph Stiglitz Thomas J. Sargent Paul Krugman N. Gregory Mankiw
See also Macroeconomic model Publications in macroeconomics Economics Applied Microeconomics Political economy Mathematical economics
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Business cycles are intervals of general expansion followed by recession in economic performance. The changes in economic activity that characterize business cycles have important implications for the welfare of the general population, government institutions, and private sector firms.

There are many definitions of a business cycle. The simplest defines recessions as two consecutive quarters of negative GDP growth. More satisfactory classifications are provided by, first including more economic indicators and second by looking for more data patterns than the two quarter definition. In the United States, the National Bureau of Economic Research oversees a Business Cycle Dating Committee that defines a recession as "a significant decline in economic activity spread across the market, lasting more than a few months, normally visible in real GDP, real income, employment, industrial production, and wholesale-retail sales."^[1]

Business cycles are usually thought of as medium term evolution. They are less related to long-term trends, coming from slowly-changing factors like technological advances. Further, a one period change, that is unusual over the course of one or two years, is often relegated to “noise”; an example is a worker strike or an isolated period of severe weather.

The individual episodes of expansion/recession occur with changing duration and intensity over time. Typically their periodicity has a wide range from around 2 to 10 years.

There are many sources of business cycle movements such as rapid and significant changes in the price of oil or variation in consumer sentiment that affects overall spending in the macroeconomy and thus investment and firms' profits. Usually such sources are unpredictable in advance and can be viewed as random "shocks" to the cyclical pattern, as happened during the 2007–2008 financial crises or the COVID-19 pandemic.