The speed of the latest rout on Wall Street is rekindling unpleasant memories of market-wide trading halts that fired time and again during the the Covid meltdown of March 2020.

The S&P 500 fell as much as 5.97% Friday, taking it within striking distance of the 7% plunge that would trip the NYSE breakers that halt all trading for 15 minutes. The circuit breakers are designed to tamp down volatility in markets and can also help address the risk of erroneous trades in an era of high-frequency trading.