The STOCK MARKET CRASH OF 1987 or "BLACK MONDAY" was the largest one-day market crash in history. The Dow lost 22.6% of its value or $500 billion dollars on October 19th 1987. 1986 and 1987 were banner years for the stock market fueled by low interest rates, hostile takeovers, leveraged buyouts and merger mania. . . . After the '87 crash, a system of circuit breakers were put in place to electronically halt stocks from trading if they fell too quickly.