A sudden, exogenous shock: Unlike most financial crises, COVID-19's market impact stemmed from an external public health emergency, not built-up financial excess.
Global lockdowns: Widespread business shutdowns to slow the virus's spread caused an abrupt halt to huge swaths of economic activity.
Extreme uncertainty: Investors faced unprecedented uncertainty about the pandemic's severity and duration, fueling rapid, severe selling.
Effects
The fastest bear market in history, with a 20%+ decline reached faster than in any prior crash.
Unprecedented monetary and fiscal response, including near-zero rates, unlimited QE, and roughly $2 trillion in initial fiscal stimulus.
One of the fastest market recoveries on record, even as employment and other parts of the real economy took much longer to fully recover.
A period of elevated inflation in 2021-2022, which many economists partly attribute to the scale of pandemic-era stimulus combined with supply chain disruptions.