Which index suffered the biggest one-day percentage loss during the 1987 global crash?

The Dow Jones Industrial Average suffered the biggest one-day percentage loss during the 1987 global crash among the major U.S. indexes commonly cited for that event.

On October 19, 1987, the Dow fell 22.6%, or 508 points. The decline was extraordinary because the index had never before experienced such a large single-day percentage drop. The S&P 500 and Nasdaq Composite also fell sharply, while markets in Europe, Asia, and elsewhere recorded major losses.

The crash followed a period of strong equity gains and rising concern about interest rates, trade imbalances, and valuation. Portfolio insurance and computerized selling added pressure when prices began to fall. The exact mix of causes remains a subject of financial research.

The Dow’s percentage loss is distinct from its point loss. Point changes depend on the index’s level, while percentages allow comparisons across eras. That distinction explains why historical accounts emphasize both 508 points and 22.6%.