The Dow Jones Industrial Average lost 22.6% during the 1987 crash’s single-day record. On October 19, 1987, the index fell 508 points, producing the largest one-day percentage decline in its history.
The fall occurred in markets around the world, not only in the United States. Concerns about economic growth, rising interest rates, trade tensions, and an overvalued market combined with computerized portfolio-insurance selling. Once prices began dropping, automated sell orders added pressure.
The percentage loss is different from the point loss often quoted in historical summaries. A 508-point fall was enormous for the Dow’s level in 1987, but later crashes could produce larger point changes without matching the same percentage. After the crash, U.S. exchanges developed circuit breakers designed to slow trading during extreme declines.