What triggers that? And who makes that call - Isn't everyone nogeiah bedavar?
It's a pre-configured circuit breaker for when the market drops.
The rules, which apply to regular trading hours only, are as follows:
Level 1: If the S&P 500 drops 7%, trading will pause for 15 minutes.
Level 2: If the S&P 500 declines 13%, trading will again pause for 15 minutes if the drop occurs on or before 3:25 p.m. ET. There will be no halt if the drop happens after that. (This would occur Monday if the S&P falls 386 points).
Level 3: If the S&P 500 falls 20%, trading would halt for the remainder of the day. (This would occur if the S&P falls 594 points).