Black Monday Stock Crash
On Monday, October 19, 1987, the Dow Jones Industrial Average fell about 22 percent in a single session, the largest one-day percentage decline in its history. Markets from Hong Kong to London to New York tumbled in succession, and the crash raised fears that a sudden collapse of confidence could trigger a broader economic catastrophe, as many believed had happened in 1929.
The years before the crash had been a remarkable bull market. Stock prices rose strongly through the mid-1980s, fueled by falling inflation, economic recovery, corporate takeovers, and growing enthusiasm among investors. By late summer of 1987, many analysts considered valuations stretched. In the weeks before the crash, concerns grew over rising interest rates, a large U.S. trade deficit, a weakening dollar, and proposed tax legislation that might dampen merger activity. Markets had already declined noticeably in the days leading up to the 19th.
On the day itself, selling began at the opening and quickly overwhelmed the system. Trading volume reached record levels, and the exchanges' infrastructure struggled to keep pace, with delayed reporting leaving investors uncertain about actual prices. Many specialists, who were supposed to maintain orderly markets, found themselves unable to absorb the flood of sell orders. The sell-off spread across the globe, and several markets abroad fell sharply the following day.
Economists still debate what caused such an extreme drop. Many point to portfolio insurance, a strategy in which institutions automatically sold stock index futures as prices fell, as a factor that may have intensified the decline. Others emphasize program trading more broadly, the overvaluation of stocks, herd behavior among investors, and the failure of market mechanisms under stress. No single explanation has won universal agreement, and there was no obvious news event large enough to account for the scale of the panic.
The aftermath was less severe than many feared. The Federal Reserve, under its new chairman Alan Greenspan, publicly affirmed its readiness to provide liquidity to the financial system, which helped calm credit markets. Stocks recovered a significant portion of their losses within the following years, and the U.S. economy avoided a recession.
The crash nonetheless prompted lasting reforms. Exchanges introduced circuit breakers, rules that pause trading when prices fall by set amounts, to give participants time to reassess. Regulators and exchanges also worked to improve coordination between stock and futures markets and to strengthen clearing and settlement systems. Black Monday remains a touchstone for discussions of market volatility, automated trading, and the role of central banks in stabilizing financial crises.