Circuit Breaker
A circuit breaker is a regulatory mechanism that temporarily halts trading on stock exchanges when price movements or index levels breach predefined thresholds. SEBI mandates market-wide circuit breakers on NSE and BSE to prevent runaway crashes and allow markets to stabilise.
Circuit breakers were introduced in Indian markets following recommendations from SEBI after the market crash of 2001, inspired by similar mechanisms in the US. They operate at two levels: index-level circuit breakers (triggered by movements in the Nifty 50 or Sensex) and stock-level circuit filters (applied to individual securities). At the index level, a 10% movement triggers a 45-minute trading halt, a 15% movement triggers a 1 hour 45 minute halt, and a 20% movement results in trading being halted for the remainder of the trading day. These thresholds are measured from the previous day's closing level.
India's index-level circuit breakers were triggered for the first time on March 13, 2020, when the Nifty 50 fell more than 10% in a single session due to COVID-19 panic. Trading was halted for 45 minutes, allowing market participants time to reassess positions and for clearing mechanisms to manage margin calls. This was a significant real-world test of the system, and while volatility remained high, the halt helped prevent a complete disorderly collapse. Prior to this, the mechanism had been tested only in simulations since its introduction.
For retail investors, understanding circuit breakers provides reassurance that markets have structural safeguards. Individual stock circuit filters operate differently from index circuit breakers — stocks can have upper and lower price bands of 2%, 5%, 10%, or 20% depending on SEBI's classification of the security. Stocks placed in the trade-to-trade segment or under the ASM (Additional Surveillance Measure) framework typically have tighter bands to curb speculative activity and manipulation.
One important caveat is that circuit breakers do not eliminate losses — they only pause them temporarily. When trading resumes after a halt, prices may continue moving in the same direction if the underlying cause of the move persists. Circuit breakers are designed to prevent 'flash crashes' driven by algorithmic or panic selling rather than fundamentals, giving rational participants time to step in. They are a market structure tool, not a guarantee of recovery.