The S&P 500 lost approximately 57% from its 2007 peak to its 2009 low during the global financial crisis.
The index reached an intraday high of 1,576.09 on October 11, 2007, before the housing and credit crisis spread through the financial system. It later reached an intraday low of 666.79 on March 6, 2009. Measured from those intraday extremes, the decline was about 57.7%.
The S&P 500 tracks 500 large U.S. companies and is widely used as a broad gauge of the U.S. equity market. Its fall therefore captured more than the performance of banks or technology firms alone. Financial companies, industrial businesses, consumer firms, and other sectors were affected by recession and restricted credit.
The exact percentage can vary slightly depending on whether analysts use closing prices or intraday values. That is why sources may describe the loss as about 57%, 57.6%, or 57.7%. The underlying historical event is the same.