• In June 2001, the Securities and Exchange Board of India (SEBI) implemented index-based market-wide circuit breakers. Circuit breakers are triggered to prevent markets from crashing, which happens when market participants start to panic induced by fears that their stocks are overvalued and decide to sell their stocks.
• This index-based market-wide circuit breaker system applies at three stages of the index movement, at 10, 15 and 20 per cent. When triggered, these circuit breakers bring about a coordinated trading halt in all equity and equity derivative markets nationwide.
• For instance, if the S&P BSE Sensex were to fall more than 10 per cent before 1 pm on a given day, circuit breakers would be triggered for a period of 45 minutes; in case it fell more than 15 per cent on or after 2 pm, circuit breakers would be triggered for the remainder of the day and in case it fell more than 20 per cent at any time of the day, the trading would be halted for the remainder of the day.

Soure:IE