NSE Circuit Breaker Rules: 10% / 15% / 20% Triggers and How Trading Halts Work

The Indian equity market has a built-in circuit breaker that can pause trading across both NSE and BSE simultaneously when the Nifty 50 or BSE Sensex moves by 10%, 15%, or 20% in either direction. These index-based market-wide circuit breakers (IBMWCBs) were last recalibrated by SEBI in 2013 and remain the rulebook for any halt on the broader benchmarks today. Knowing precisely when a halt triggers, how long it lasts, and how the pre-open phase resumes after a halt is essential for any active trader heading into a high-volatility session.

This pre-open primer walks through the SEBI/NSE circuit breaker framework that governs every trading session: when it triggers, how the halt timing depends on the time of day, why individual stock price bands work differently, and what historical instances illustrate the rule in action. The controlling instrument is SEBI's circular dated 3 September 2013 on the Index-Based Market-Wide Circuit Breaker mechanism, which harmonised the trigger calculation across both exchanges.

Market Snapshot

The pre-open session on the NSE runs from 09:00 IST to 09:08 IST for order entry, modification, and cancellation, followed by an order-matching window from 09:08 IST to 09:12 IST. Continuous trading then runs from 09:15 IST to 15:30 IST. Index-based market-wide circuit breakers can engage at any point during continuous trading on either the Nifty 50 or BSE Sensex; whichever index breaches the threshold first triggers the halt across both exchanges per SEBI's 2013 harmonised framework.

The three thresholds defined by SEBI's 2013 update are 10%, 15%, and 20%, applied symmetrically to upward and downward moves from the previous day's official closing index value. The halt duration is not fixed: it depends on which threshold is breached and at what time of day the breach occurs. The earlier in the session a circuit breaker triggers, the longer the halt and the longer the post-halt pre-open call auction that follows before continuous trading resumes.

The previous-close reference for the circuit breaker calculation is the official closing index value from the immediately preceding trading day, not the special pre-open opening price. Once a circuit breaker is triggered, all equity cash and equity derivatives trading on both NSE and BSE is halted in unison — index futures, index options, single-stock futures, and single-stock options all stop together. Want to model how a 10% market-wide drop affects long-term equity contributions? Try our SIP calculator to plot monthly contributions through volatility, or our lumpsum calculator to test single-shot deployment against a sharp drawdown.

What Moved Yesterday

Index-wide circuit breakers triggering in Indian markets are uncommon enough that each instance is historic. The 10% downside threshold under the post-2013 framework was famously breached on 13 March 2020 and again on 23 March 2020 during the early COVID-19 panic, when the Nifty 50 and Sensex collapsed within minutes of the open and the lower circuit halted both exchanges for 45 minutes before a post-halt pre-open call auction reopened price discovery. The 17 May 2004 session, when the Sensex fell sharply on UPA-1 election results, is the textbook pre-2013 instance under the older threshold framework.

In a normal session, however, most movement stays well within the price-band tolerance set on individual stocks rather than the index-wide trip wires. Stock-specific price bands operate separately from IBMWCB rules and are applied scrip-by-scrip by NSE based on liquidity and segment, typically at 2%, 5%, 10%, or 20% on either side of the previous close. Stocks in the Futures and Options (F&O) segment generally do not have a fixed price band but operate under a dynamic price-band mechanism that flexes in 5% increments after a cooling-off period.

The asymmetry is deliberate: index-level circuit breakers interrupt trading only when the broad market is in genuine free-fall or vertical melt-up, while stock-level price bands manage idiosyncratic single-name volatility without halting the wider market. Derivative traders should note that mark-to-market settlement is paused during a halt but resumes once trading reopens; for a primer on margin mechanics, see our margin trading glossary entry and the futures and options glossary.

What to Watch Today

The first thing every trader should mentally pre-compute is the absolute index level that corresponds to each threshold relative to yesterday's close. If the Nifty 50 closed at X, then the 10% downside trigger sits at 0.90X and the 10% upside trigger at 1.10X; the 15% and 20% triggers follow the same proportional logic. The same applies to the Sensex on its own previous close. Knowing these absolute levels in advance avoids panic recalculation during a fast-moving session.

The halt durations under the 2013 SEBI circular are explicitly time-of-day sensitive. The 10% threshold breached before 13:00 IST triggers a 45-minute trading halt followed by a 15-minute pre-open call auction; if the same 10% breach occurs between 13:00 and 14:30 IST, the halt is shortened to 15 minutes plus the 15-minute pre-open; after 14:30 IST, no halt is enforced and trading continues to the close. The 15% threshold triggers a 1 hour 45 minute halt before 13:00, a 45-minute halt between 13:00 and 14:00, and closure for the rest of the day if breached after 14:00 IST. The 20% threshold halts trading for the rest of the day regardless of when in the session it occurs.

A nuance often missed: during the halt itself, all open orders in the order book are not cancelled. They are retained, and on resumption, a special pre-open call auction collects fresh orders and computes an equilibrium re-opening price before continuous trading restarts. Investors running step-up SIPs or systematic equity programmes are not directly affected by intraday halts because mutual fund schemes are priced on the official closing NAV, computed from end-of-day index values regardless of intraday halts.

For derivatives traders, mark-to-market settlement is suspended during a halt, but margin obligations already issued must still be met. The exchange does not issue fresh margin calls during the halt window itself, but on resumption, any incremental margin requirement based on the post-halt price is enforced. The 2013 circular also clarifies that a given threshold can trigger only once per day; once the 10% halt has occurred and trading has resumed, the next live threshold becomes 15%, not another 10%. This staged structure echoes the broader SEBI effort to keep Indian markets resilient under stress, mirrored in the operational shortening discussed in our piece on SEBI's T+1 vs T+0 settlement cycle.

FAQ

When were the current 10/15/20 circuit breaker thresholds set?

SEBI fixed the current three-tier threshold structure in its circular dated 3 September 2013 on the Index-Based Market-Wide Circuit Breaker mechanism. The earlier framework had different percentage bands and trigger levels; the 2013 update harmonised the calculation between NSE and BSE so that whichever exchange's benchmark — Nifty 50 or BSE Sensex — breaches a threshold first triggers the market-wide halt on both exchanges simultaneously.

Does the circuit breaker apply to commodity and currency derivatives?

The IBMWCB framework as defined by SEBI's 2013 circular applies to equity cash and equity derivatives. Commodity derivatives on MCX/NCDEX and currency derivatives on NSE/BSE operate under separate price-band rules issued by SEBI for those specific segments, and a halt on the equity index does not automatically halt those segments.

What is the difference between an index circuit breaker and a stock price band?

An index circuit breaker halts all equity trading market-wide when the Nifty 50 or Sensex moves 10%, 15%, or 20% from the previous close. A stock price band restricts a single security to a daily move of 2%, 5%, 10%, or 20% from previous close, applied scrip-by-scrip. Stocks in the F&O segment operate under a dynamic price band that flexes in 5% increments rather than a fixed daily cap.

How is the post-halt pre-open different from the morning pre-open?

The morning pre-open runs 09:00 to 09:08 IST for order entry, with matching from 09:08 to 09:12 IST. The post-halt pre-open is shorter — typically 15 minutes — and uses the same call auction matching mechanism to discover an equilibrium re-opening price. Existing orders from before the halt remain in the order book and participate in the post-halt price discovery alongside fresh orders.

What was the most recent instance of a circuit breaker triggering on the Nifty?

The most prominent post-2013 instances were 13 March 2020 and 23 March 2020 during the COVID-19 risk-off, when the lower 10% threshold was breached on the Nifty 50 and Sensex within minutes of the open, halting trading for 45 minutes each time. These remain the textbook examples of how the 2013 IBMWCB framework operates in live, fast-moving conditions.

Are mutual fund SIPs affected if a circuit breaker triggers during the day?

No. Mutual fund schemes are priced on the official closing NAV computed at the end of the trading day. An intraday halt simply means the closing index — and therefore the closing NAV — is computed from the price prevailing at 15:30 IST or whenever the halt-shortened session ends. A live SIP investor's purchase is allotted at that closing NAV regardless of intraday halts.

Does a circuit breaker reset every trading day?

Yes. The threshold ladder resets on each trading day relative to that day's previous-close reference value. A 10% halt on a given session does not carry over to the next day; the next session opens with the full 10/15/20 ladder available again, calculated against a fresh previous-close reference index value.

Do circuit breakers freeze open positions on derivatives?

During a halt, open derivative positions are frozen in the sense that no new trades can be entered, modified, or cancelled. Mark-to-market settlement is suspended during the halt window but resumes on the post-halt pre-open price once continuous trading restarts. Margin requirements computed on the post-halt price are then enforced for the remainder of the session.