How stock market circuit breakers work and why crypto has none

What is a circuit breaker in the stock market?

It is an automatic stop on trading, triggered by how far a benchmark index has moved in one day. The point is to interrupt a fall that is feeding on itself. Sellers cannot find buyers, prices drop further, and that drop brings more sellers.

A halt does not set a price or reverse a loss. It gives everyone time to read the news and decide before the next order lands.

In India the trigger is the Nifty 50 or the Sensex, whichever moves first. The NSE's circuit breaker page says a trigger brings a coordinated halt in all equity and equity derivative markets nationwide.

This is separate from the price band on a single stock. A band limits how far one share can move. A circuit breaker stops the whole market.

How do India's three stages work?

There are three trigger levels, each measured against the previous day's closing level of the index. The exchange recalculates the limits every day.

Stage one: a 10 percent move

The length of the halt depends on the clock. A fall of 10 percent before 1:00 pm halts the market for 45 minutes. Between 1:00 pm and 2:30 pm the halt is 15 minutes. At or after 2:30 pm there is no halt at all.

Stage two: a 15 percent move

Before 1:00 pm the halt runs 1 hour 45 minutes. From 1:00 pm until 2:00 pm it runs 45 minutes. At or after 2:00 pm trading stops for the rest of the day.

Stage three: a 20 percent move

Trading stops for the rest of the day, whatever the time.

After the first two stages the market reopens through a 15-minute pre-open call auction, so orders are matched at one price before continuous trading resumes.

As a worked example, the NSE page read for this piece shows the Nifty 50 closing at 23,146.15 on 16 October 2026. Ten percent of that is 2,314.60 points, 15 percent is 3,471.90 points and 20 percent is 4,629.25 points. A fall of 2,314.60 points from that close, before 1:00 pm, would have stopped the market for 45 minutes.

Source: NSE India, circuit breaker page, read on 18 October 2026.

Where did the idea come from?

It came from one day. On 19 October 1987 the Dow Jones Industrial Average fell 508 points, or 22.6 percent, in a single session. Federal Reserve History calls it the largest one-day decline in the history of that index.

The same essay says exchanges had been powerless to step in against heavy selling. Regulators afterwards wrote rules that let exchanges halt trading in exceptionally large declines. On the New York Stock Exchange today the S&P 500 triggers pauses at 7, 13 and 20 percent.

The same essay records what followed. The Dow gained back 288 points, 57 percent of the fall, in two sessions. Within two years US stocks passed their earlier highs. A halt did not cause that recovery, and nobody can say what the day would have looked like with one.

The lesson regulators took was narrower. A market that cannot pause makes every participant decide at the speed of the fall.

Why does crypto have no circuit breaker?

Because no single body runs the market. Bitcoin trades around the clock on hundreds of venues in many countries, and a halt on one venue leaves the others open.

CoinDesk reported on 13 April 2026 that the Bank of Korea had proposed stock-style circuit breakers for its domestic crypto exchanges. The trigger was a February error at a Korean exchange. A promotion paid out about 60 trillion won in phantom bitcoin, and the price on that exchange fell 17 percent.

The same CoinDesk report states the open problem. If one exchange paused for 20 minutes, bitcoin would keep trading elsewhere, and the paused venue's price would snap to wherever the global market had moved.

Some venues do run narrower brakes. CoinDesk says CME Group halts bitcoin futures for two minutes when prices move 10 percent inside 60 minutes. That brake covers one contract on one exchange, and bitcoin itself keeps trading.

Crypto has local controls on some venues and no market-wide halt. A fall that starts on a Saturday night runs until buyers show up.

What does that mean for someone holding crypto?

The halt in equities does one useful thing. It makes you wait before you act. Take the exchange out of the picture and that job moves to you, and a decision made mid-fall is rarely the one you would make on a calm day.

My position is that a circuit breaker is the wrong thing to want from crypto. A halt pauses an order book. What protects a portfolio is a rule written before the fall, one that tells you what to do without asking how you feel.

Take a ₹1 crore portfolio with a crypto sleeve (the slice of the portfolio held in crypto) capped at 3 percent, which is ₹3,00,000.

Suppose, purely as an illustration, crypto halves while everything else stays flat. The sleeve is now ₹1,50,000 and the portfolio is ₹98,50,000, so the sleeve is 1.52 percent of it.

A written rule that restores the 3 percent cap does not need a halt. Three percent of ₹98,50,000 is ₹2,95,500. Topping up the sleeve by ₹1,45,500 (₹2,95,500 minus ₹1,50,000) is a sizing decision made in advance, on a schedule, with the arithmetic done.

The rule can run the other way too. If the sleeve grows past its cap, it is trimmed back. Both directions are mechanical, and neither needs a view on where prices go next.

Such a rule has three parts. The first is a cap on the sleeve, stated as a share of the whole portfolio. The second is a check on a fixed date, and the third is a written instruction for when the cap is breached either way.

This is what a rebalance is: bringing a position back to its target weight. The four QSI indices at Qatobit rebalance monthly on a published methodology, so the rule for what the basket holds is written before the market moves. If you want to invest in that structure, QSI Growth is the index to read first.

Where to read next

For what a market with no buyers looks like from inside a portfolio, see what a flash crash does to a portfolio. For how deep past crypto falls ran, read how far past bitcoin crashes went. And for what an index does while the market falls, see how a crypto index rebalances during a crash.

India's equity market pauses itself at 10, 15 and 20 percent. Crypto does not pause at any level, so the only stop a crypto position gets is the one its owner wrote down in advance.

Frequently asked questions

What is a circuit breaker in the stock market?

It is an automatic halt in trading when a benchmark index falls or rises by a set percentage in one day. In India the triggers are 10, 15 and 20 percent on the Nifty 50 or the Sensex, whichever moves first.

How long does an Indian market halt last?

A 10 percent move before 1:00 pm halts trading for 45 minutes, and a 15 percent move before 1:00 pm halts it for 1 hour 45 minutes. A 20 percent move ends trading for the day. The halts shorten later in the session, and a 10 percent move at or after 2:30 pm brings none.

Is there a circuit breaker in crypto?

There is no market-wide circuit breaker for crypto. Some venues run their own limits, such as CME Group's two-minute halt on bitcoin futures after a 10 percent move in 60 minutes, but bitcoin keeps trading on other venues.

What is the difference between a circuit breaker and a stock's price band?

A price band limits how far a single share can move in a day. A market-wide circuit breaker stops trading in every equity and equity derivative contract once the Nifty 50 or the Sensex hits a trigger level.

Did circuit breakers exist before the 1987 crash?

According to Federal Reserve History, exchanges were powerless to intervene against heavy selling in 1987, and circuit breaker rules were developed afterwards. India's index-based breakers have operated since 2 July 2001, per the NSE.

Crypto investments are subject to market risk. Not financial advice.