Which U.S. stock exchange was at the center of the 1987 Black Monday crash's trading-floor response?

The New York Stock Exchange was at the center of the trading-floor response during the 1987 Black Monday crash.

On October 19, 1987, selling overwhelmed markets around the world. The NYSE’s trading floor handled a huge volume of orders as prices plunged, while many investors and brokers struggled with delayed information and overloaded communications systems.

The crash affected more than the United States. Hong Kong, Australia, Britain, and other markets also experienced severe declines. The Dow Jones Industrial Average fell 22.6%, its largest one-day percentage loss, and the shock raised fears that the financial system itself could become unstable.

The exchange was not the sole cause of the crash. Computerized portfolio insurance and program trading were important factors, alongside high valuations and investor psychology. Afterward, regulators developed coordinated trading halts, now commonly called circuit breakers, to slow future panics.