Which U.S. market regulator introduced the circuit breaker after the 1987 stock-market crash?

The Securities and Exchange Commission introduced the circuit breaker after the 1987 stock-market crash.

The October 1987 collapse exposed how rapidly computerized and linked markets could move. In response, the SEC approved new market-wide trading halts, commonly called circuit breakers, designed to pause trading after exceptionally large declines.

The original system used percentage thresholds tied to the Dow Jones Industrial Average. A pause was intended to give investors time to absorb information and reduce panic-driven orders rather than allowing an uninterrupted cascade of selling.

Modern U.S. rules use thresholds based on the S&P 500 rather than the Dow. Circuit breakers do not prevent prices from falling; they temporarily interrupt trading when specified limits are reached.