The bourses fix the circuit breaker limit at the end of every quarter for the next three-month period, based on the closing level of the index in the quarter.

A 10 per cent movement triggers a trading halt for one hour, while a 15 per cent rise or fall leads to the market closing for two hours and a 20 per cent move leads to trading being suspended for the entire day. “The exchange implements on a quarterly basis the index based market wide circuit breaker system for the quarter beginning January 1 to March 31, 2008,” an exchange statement said here. The circuit breaker will be triggered if the Sensex goes up or down over the previous day’s closing by 10 per cent or equivalent of 2,025 points, 15 per cent or equivalent of 3,050 points and 20 per cent or equivalent of 4,050 points any day during the January-March quarter, the statement said.

Coordianted halt

This circuit breaker brings about a coordinated trading halt in all equity and equity derivative markets nationwide, it said.

The market wide circuit breakers would be triggered by movement of either Sensex or the NSE S&P CNX Nifty whichever is breached earlier. In case of a 10 per cent movement of either of Sensex or Nifty indices, there would be a one-hour market halt if the movement takes place before 1 pm.

If the movement takes place at or after 1 pm but before 2.30 pm, there will be a trading halt for half-an hour.