On Black Monday, October 19, 1987, the Dow Jones Industrial Average lost 508 points.
That fall represented 22.6% of the Dow’s value, making it the largest one-day percentage decline in the index’s history. The decline occurred in the United States during a worldwide equity-market sell-off, with markets in several countries also suffering exceptionally large losses.
The point figure can be confusing because the Dow’s numerical level was much lower in 1987 than it is today. A 508-point fall therefore represented a much larger percentage move than the same number of points would now. The percentage loss, rather than the raw point total, is the standard way historians compare crashes across eras.
Researchers have linked the crash to several factors, including rising interest rates, trade tensions, investor anxiety and computerized portfolio-insurance selling. No single cause explains every market’s move, and the crash did not produce a prolonged economic depression comparable to the 1930s.