A sudden and significant decline in the value of a market. A crash is most often associated with an inflated stock market. Causes for a crash may include an economic bubble in which securities, or other investments, are trading at prices far above their intrinsic value, or a highly-leveraged market in which debt is used to finance further investment. Crashes are distinguishable from a bear market by their rapid decline in a number of days, rather than a decline over a longer period of time. A crash can lead to a depression in the overall economy and subsequent bear market.


A crash is both an economic phenomenon and a psychological one. Investors who see a rapid decline in the value of a particular stock may sell off other securities as well, leading to the possibility of a vicious spiral marked by negative crowd behavior. In order to reduce the effect of a crash, many stock markets employ circuit breakers designed to halt trading if declines cross certain thresholds.