Black Monday Stock Crash
Stock markets worldwide crashed on Black Monday, with the Dow falling 22.6% in a single day
October 19, 1987
The Largest Single-Day Market Drop
On October 19, 1987, stock markets around the world crashed in a single trading day. The Dow Jones Industrial Average fell 22.6 percent — the largest single-day percentage drop in the index's history, exceeding even the worst days of the Great Depression. The crash happened with terrifying speed. In Hong Kong and Australia, markets had already fallen sharply before U.S. markets opened. As New York opened, sell orders overwhelmed the system. Trading programs that automatically sold stocks when prices fell a certain amount amplified the decline, creating a feedback loop of selling.
Why It Happened
The causes of Black Monday have been debated for decades. Markets had been rising steeply for years and many analysts believed stocks were overvalued. Rising interest rates and trade deficit concerns were contributing factors. But the immediate trigger was portfolio insurance — a computerized trading strategy that was supposed to protect investors by automatically selling stock futures when prices fell. When markets began declining, these programs all triggered simultaneously, creating a flood of sell orders that no buyers could absorb. The interconnectedness of global markets meant the crash spread instantaneously around the world.
Recovery and Reform
Unlike the 1929 crash, Black Monday did not trigger a depression. The Federal Reserve moved quickly to reassure markets by injecting liquidity into the banking system. Markets recovered most of their losses within two years. The crash did, however, lead to significant reforms. Stock exchanges introduced "circuit breakers" — automatic trading halts that kick in when markets fall too far too fast, giving traders time to pause and assess the situation. These mechanisms have been triggered several times since, including during the market volatility of March 2020. The Great Depression crash of 1929 offers a stark comparison of a crash with far worse long-term consequences.