will bring a nationwide trading halt for up to one hour in a day till October 11, while such circuits would be calculated on a daily basis thereafter.
Markets regulator Sebi had asked stock exchanges last month to begin calculating the trading halt circuit breakers on a daily basis, as against the prevailing practice of such trigger points being calculated on a quarterly basis.
In separate circulars, BSE and NSE said that the circuit breakers for 10 per cent, 15 per cent and 20 per cent movements in Sensex and Nifty have been calculated on the basis of quarter-end figures for trading till October 11.
Thereafter, the circuit triggers would be determined as per Sebi's latest direction of daily calculation.
So far, the exchanges have been calculating the trigger values on the basis of closing value of Sensex or Nifty at the end of every quarter, the latest being as per the value on September 30.
As per the circuit-breaker system, in case of a 10 per cent movement of either of these indices (1,950 points for Sensex or 570 points for Nifty), there would be a one-hour market halt if the movement takes place before 1300 hrs.
In case such a movement takes place at or after 1300 hrs but before 1430 hrs there will be a trading halt for 30 minutes. If the movement takes place at or after 1430 hrs there will be no trading halt at the 10 per cent level and the market will continue trading.
At 15 per cent (2,900 points for Sensex or 860 points for Nifty), there will be a two-hour market halt if the movement takes place before 1300 hrs.
If the 15 per cent trigger is reached on or after 1300 hrs but before 1400 hrs, there will be a one-hour halt. If the 15 per cent trigger is reached on or after 1400 hrs, the trading will be halted for the remainder of the day.
A movement of 20 per cent (3,875 points for Sensex and 1,150 points for Nifty) would lead to the trading being halted for the remainder of the day.
The percentages have been calculated on the basis of closing value of Sensex as on September 30, 2013. These percentages are translated into absolute points of index variations (rounded-off to the nearest 25 points in case of Sensex).
These triggers would be applicable for the period October 1-11, 2013.