The S&P 500 fell about 34% during the COVID-19 stock-market crash from February to March 2020.
The decline began after investors recognized the worldwide economic threat posed by COVID-19, including business closures, travel restrictions, supply disruptions, and uncertainty about public-health measures. From its February 19, 2020, closing high to its March 23 low, the S&P 500 lost roughly one-third of its value.
The index tracks large U.S. companies and is weighted by market capitalization, so the largest firms have the greatest effect on its movement. It is therefore different from the price-weighted Dow and the technology-heavy Nasdaq Composite. Markets recovered sharply after central-bank intervention, fiscal support, and improving expectations, although the economic effects of the pandemic continued well beyond the index’s low.