A bear market occurs when a security falls at least 20 percent from a recent peak.
While bear markets typically occur during periods of economic weakness, they often begin when the economy looks strong. That’s because the stock market is forward-looking, often six or 12 months into the future.
There have been 26 bear markets in the history of the S&P 500, according to Dow Jones Market Data.
Bear markets have no set length as their duration depends on a number of factors including the economy and decisions specific to a company or industry.
The average bear market has lasted 142 trading days and seen a decline of 36 percent, the data showed. After exiting its bear market, the S&P 500 has taken an average of 1,120 days to return to its previous peak, As a reference, there were 252 trading days last year.