Black Monday prompted the United States to create circuit breakers for stock trading.
The 19 October 1987 market collapse exposed how quickly selling could spread through linked exchanges and computerized trading systems. The Dow Jones Industrial Average lost 22.6% in one session, while other major markets also recorded severe declines. Regulators wanted mechanisms that could temporarily slow trading during exceptional price movements.
In the United States, exchange-wide circuit breakers were introduced after recommendations from the Brady Commission and later regulatory work. These rules pause trading when broad market indexes fall by specified amounts, giving investors time to assess information and reducing the possibility of automatic orders feeding one another.
Circuit breakers do not prevent losses or guarantee stable markets. They are designed to create a pause, and their thresholds and procedures have changed over time. The system was tested during later crises, including the March 2020 market turmoil. Black Monday therefore influenced not only market history but also the architecture of modern trading safeguards.