Circuit Breaker

A circuit breaker is the market's emergency brake. When prices move violently, trading is paused to let panic cool, information spread, and rationality return, preventing a freefall driven by pure fear.

How it works in India

There are two distinct kinds.

Individual stock price bands cap how far a single scrip can move in a day, with limits set at 2%, 5%, 10% or 20% depending on the stock. Once a stock hits its upper circuit, there are only buyers and no sellers, so trading effectively freezes at that price; at the lower circuit, the reverse. Stocks in the F&O segment generally do not have these fixed bands, instead using dynamic price ranges.

Market-wide (index-based) circuit breakers apply to the whole market and trigger on movements of the Nifty 50 or the BSE Sensex, whichever breaches first, at three thresholds: 10%, 15% and 20%. When tripped, trading halts across all equity and equity-derivative segments simultaneously.

The halt length depends on the level and the time of day. Roughly, a 10% move triggers a pause early in the session but none after 2:30 PM; a 15% move triggers a longer halt; and a 20% move shuts the market for the rest of the day. After a halt, trading resumes with a pre-open call-auction session.

Why it matters

Circuit breakers protect ordinary investors during crashes and crazes alike. India saw market-wide halts during the March 2020 Covid crash. They buy time to prevent algorithmic cascades and let buyers and sellers re-assess instead of stampeding.

Common mistakes

A stock locked in an upper circuit is not a guaranteed winner, it is often illiquid, possibly being manipulated, and you may be unable to sell when it reverses. A lower circuit is a trap of a different kind: you cannot exit, and the stock can hit successive lower circuits for days. Treat repeated circuit hits, especially in small or micro-cap names, as a red flag for liquidity and operator activity, not as a quick-money signal.