An exhausted trader at the end of the worst day in stock market history, “Black Monday”, October 19, 1987. After “Black Monday”, stock exchanges instituted circuit breakers, or trading pauses, when there are large declines.

By the end of October, stock markets in Hong Kong, Australia, Spain, the United Kingdom, the United States and Canada had fallen 45.5%, 41.8%, 31%, 26.45%, 22.68% and 22.5% respectively. New Zealand’s market was hit especially hard, falling about 60% from its 1987 peak