The BSE and NSE stopped trading for 45 minutes starting from little past 9.20 am.
To curb excessive volatility, circuit breakers are triggered on the basis of three thresholds for stock movement -- 10 per cent, 15 per cent and 20 per cent.
The BSE and the NSE compute the index circuit breaker limits for 10 per cent, 15 per cent and 20 per cent levels on a daily basis based on the previous day's closing level of the index rounded off to the nearest tick size, HDFC Securities said citing regulatory framework.
For 10 per cent movement before 1 pm, trading is halted for 45 minutes. The break time is 15 minutes for 10 per cent movement between 1 pm and 2.30 pm while there would be no halt in case the same happens after 2.30 pm.
As per norms, trading would be halted for 1.45 hours if there is 15 per cent movement before 1 pm and 45 minutes for such movement between 1 pm and 2 pm. Trading would be stopped for the day in case the 15 per cent movement is on or after 2 pm.
Finally, a 20 per cent movement at any point of time would result in complete halt of trading for the day.
Geojit Financial Services Chief Investment Strategist V K Vijaykumar said the last time there was a circuit freeze and trading halt was on January 22, 2008.
There was also a brief trading halt on the National Stock Exchange on October 5, 2012 due to a freak trade.
Before trading was halted on Friday, nearly Rs 13 lakh worth investor wealth evaporated in less than 15 minutes of market open.
"Last time, we had a circuit freeze and halt to trading was on January 22, 2008 when the Sensex had its biggest till date loss of 1,408 points. This was also the first ever four-digit crash in the Sensex. The global financial crisis and fears about a global recession had caused the crash," Vijaykumar said.
HDFC Securities Head of Retail Research Deepak Jasani said halting of trade is basically "cooling down period" for investors. RAM MKJ