The event highlighted the dangers of fully automated, unmonitored trading, fundamentally changing how risk is managed on Wall Street.
Unlike the 1929 crash, Black Monday did not result in a long-term depression. The market recovered its losses within two years, according to The Guardian.
Black Monday, which occurred on , stands as a defining moment in financial history, marking the largest one-day percentage decline in stock market history, with the Dow Jones Industrial Average (DJIA) plummeting 22.6%. This event marked the first truly global financial crisis, as panic spread from Asian markets to Europe and the U.S., resulting in roughly US$1.71 trillion in global losses.
A proposed tax bill in the U.S. House of Representatives designed to make corporate takeovers more expensive, paired with statements about allowing the dollar to fall, reportedly lit the fuse, say reports in the International Banker and Investopedia. The Day’s Events (Oct 19, 1987)
The immense volume of sell orders paralyzed computerized trading systems, making it impossible to accurately price stocks.
A significant driver was the widespread use of computerized "program trading" designed to sell stocks automatically as prices fell, intended to hedge against losses. This backfired, creating a, "cascading feedback loop" where selling sparked more selling.
