The S&P 500 lost approximately 57 percent from its 2007 peak to its 2009 low.
The index reached an intraday record of 1,576.09 on October 11, 2007, before the global financial crisis drove markets lower. It eventually reached an intraday low of 666.79 on March 6, 2009.
The decline accompanied a severe crisis involving U.S. housing, mortgage-backed securities, leveraged financial institutions, and frozen credit markets. The bankruptcy of Lehman Brothers in September 2008 intensified panic, but the market downturn had already begun months earlier.
The 57 percent figure measures the peak-to-trough fall in the S&P 500 during the bear market. It should not be confused with the percentage loss on a single day or with the performance of every stock. The index began a major recovery after March 2009, though the economic effects of the crisis continued for years.