The Dow Jones Industrial Average’s lowest closing value during the 1987 crash month was 1,738.74. The index reached that close on October 19, 1987, the session known as Black Monday.
The Dow had closed at 2,246.74 on the previous Friday, October 16. Monday’s fall of 508 points represented a decline of 22.6%, an unprecedented percentage loss for the index. Intraday trading was also exceptionally volatile, with market liquidity becoming difficult as sell orders overwhelmed available buyers.
The decline was part of an international market shock rather than an isolated New York event. Equity markets in Europe, Asia, and other regions experienced major losses around the same period. The causes debated afterward included valuation concerns, macroeconomic tensions, portfolio insurance, and program trading.
The crash prompted regulators to consider how trading systems behaved under extreme stress. Circuit breakers and coordinated procedures were introduced to create pauses during steep declines. The Dow recovered over time, but the event remains a benchmark for discussions of market contagion and automated selling.