Adopting new, U.S. market-wide circuit breakers to halt precipitous drops in individual stocks is a done deal, a source said on Tuesday, five days after a severe market plunge rattled investors and perplexed regulators.

The circuit breakers would likely trip when individual stocks fell by a set amount in a set time frame. The U.S. Securities and Exchange Commission hosted exchange heads at a meeting Monday, and said afterward the parties agreed to a framework that would strengthen circuit breakers.

(Reporting by Jonathan Spicer, editing by Gerald E. McCormick)