Stats › Volatility and VIX › Circuit breakers
Market circuit breakers and trading halts
A circuit breaker is a rule that stops all trading in US stocks when the market falls far enough, fast enough. The thinking behind it is simple. If prices are dropping so quickly that nobody can tell a real price from a backlog of unfilled orders, everyone gets fifteen minutes to breathe.
This page has the three thresholds, what each one actually does, and the complete list of days they have ever fired. That list is short. Five trading days in the whole record, and four of them fall inside the same nine day stretch of March 2020. I put it together because this is one of those mechanisms people know exists without ever knowing the numbers, and the numbers are exactly what stop you panicking when a headline says trading has been halted. There's a short section on the near misses too, because knowing how close the market has come without triggering anything tells you as much as the trigger list does.
The thresholds and the trigger history come from the NYSE's own working group report, with the 1987 background from a second source. Both are at the bottom with the date I read them. The NYSE document is a dry PDF and it is the primary text, so if something on this page looks wrong to you, that's where to go and settle it. I'd rather you did that than take my word for how the rules work, especially since they've already been rewritten once.
US market wide circuit breakers halt all equity trading when the S&P 500 falls by set amounts from the previous close: 7% and 13% each cause a fifteen minute halt, and 20% closes the market for the day. They have been triggered on only five trading days in history. One was 27 October 1997 under the older Dow points based rules. The other four were all in March 2020, on the 9th, 12th, 16th and 18th. Level 3 has never been triggered.
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