Market Wide Circuit Breaker: What Happens When Nifty or Sensex Falls 10%, 15% or 20% in a Day

Triggers at 10%, 15% and 20% of the previous close, on Nifty 50 or Sensex, whichever breaks first. A 20% move ends trading for the day. Reopening starts with a 15-minute pre-open call auction.

The market wide circuit breaker is the exchange’s emergency brake. When an index moves far and fast, trading across the whole market stops, so that panic or euphoria can settle and fresh information can be absorbed.

This guide covers the three trigger levels, the halt durations in a table, how the market reopens, how the index version differs from a single-stock circuit, and what long-term investors should do on a day when it triggers.

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What Is a Market Wide Circuit Breaker?

The circuit breaker is an index-based system that operates at three stages: 10 percent, 15 percent and 20 percent. It is triggered by a move in either the Nifty 50 or the Sensex, whichever is breached first, measured against the previous day’s close. When it triggers, trading stops on both exchanges in the equity and equity derivatives segments.

The exchanges recalculate the trigger levels each day in index points. You can see the day’s levels on the exchange website, so a large percentage is not something you have to calculate yourself.

Circuit Breaker Rules: Halt Duration by Time

The length of the halt depends on how far the index has moved and the time at which the trigger is hit. A later trigger means a shorter halt, because less of the session remains.

How the Market Reopens After a Halt

When a halt ends, the market reopens with a 15-minute pre-open call auction session, similar to the one at the start of the day. Orders that were pending when the halt began are cancelled, so you need to place fresh orders after the reopening.

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This design gives participants a chance to reassess prices before continuous trading resumes, and it reduces the risk of a disorderly rush at the reopening bell.

Index Circuit Breaker vs Single Stock Circuit

The index circuit breaker works on the whole market. A single stock circuit works on one share and stops trades beyond a daily price band, such as 5, 10 or 20 percent. A stock can hit its band every day without any effect on the rest of the market, but an index breach halts everyone.

Index triggers are rare because the Nifty 50 and the Sensex are made of large, liquid companies and seldom move 10 percent in a session. One well-known occasion was in March 2020, when a sharp global sell-off pushed the benchmark down about 10 percent in a day and both exchanges halted trading.

What Should an Investor Do When a Circuit Breaker Triggers?

• Do not rush to place orders during the halt. Orders are cancelled, and prices at the reopening can differ from what you expect.
• Check whether your positions carry margin or stop-loss levels that could be affected on the reopening.
• Long-term investors usually gain more from holding to their plan than from reacting to a single day.
• Keep cash handy for margin requirements, because volatility often rises after a halt.

During a trading halt, review your outstanding orders, because some may need changes before the market reopens. An index circuit breaker exists to give everyone time to think, so avoid panic decisions.

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Conclusion

The market wide circuit breaker is a safety mechanism, not a signal about where markets are going next. It pauses trading at 10, 15 and 20 percent index moves, reopens through a pre-open call auction, and cancels pending orders.

Knowing the rules in advance helps you stay calm on the rare day it triggers, and keeps you from acting on impulse during the pause.

Frequently Asked Questions

What is a market wide circuit breaker?

Ans. It is an index-based mechanism that halts all trading on the exchanges when the Nifty 50 or Sensex moves 10, 15 or 20 percent from the previous day’s close. The trigger can be on a rise or a fall, and the halt applies to equity and equity derivatives.

How long does trading halt on a 10 percent fall?

Ans. If the 10 percent trigger is hit before 1:00 pm, trading halts for 45 minutes followed by a 15-minute pre-open call auction. Between 1:00 pm and 2:30 pm the halt is 15 minutes plus the pre-open session, and after 2:30 pm there is no halt.

What happens at a 20 percent move?

Ans. A 20 percent move in either index at any time during market hours ends trading for the rest of the day. The market reopens normally on the next trading day, and the day’s trades stay as they were before the halt.

What happens to my pending orders during a halt?

Ans. Orders that were outstanding when the halt began are cancelled by the exchange. After the market reopens, you must place fresh orders. Check your stop-loss and limit orders so that you are not left without protection.

Is a market-wide circuit breakers the same as a stock’s upper or lower circuit?

Ans. No. A stock circuit limits price movement in a single share to a daily band, and trading in other shares continues. The circuit breaker is triggered by a large move in an index and stops trading across the market.

Which index triggers the circuit breaker?

Ans. Either the Nifty 50 on the NSE or the Sensex on the BSE. Whichever index breaches the level first triggers the halt, and the halt applies to both exchanges so that trading stays aligned.

Has the circuit breaker been triggered before?

Ans. Yes. It was triggered in March 2020, when a sharp global sell-off pushed the Indian benchmark down by about 10 percent in a session. It is a rare event, because the indices are made of large and liquid companies.