Circuit Breakers and Halts
Mechanisms that stop trading, at the market level and at the individual security level. They pause the market rather than preventing the move.
MadStockAlerts Research · Updated August 28, 2026
What to take away
- Market-wide circuit breakers halt all trading at defined index declines.
- Limit up-limit down bands halt individual securities that move too far too fast.
- News and regulatory halts are a separate category with different mechanics.
- A halt removes the ability to exit for its duration.
- Reopening is by auction, and the reopening price can be far from the halt price.
MAD Academy Training Video · 0:45
When the Market Stops on Purpose
Halts are designed to interrupt a disorderly market, and knowing which kind you are looking at tells you what happens next.
This lesson is part of a Stock Alerts + Tools plan.
The market-wide levels
| Level | Decline in the reference index | Effect |
|---|---|---|
| 1 | 7 percent | A 15-minute halt, if before a stated time in the afternoon |
| 2 | 13 percent | A further 15-minute halt on the same condition |
| 3 | 20 percent | Trading halts for the remainder of the session |
The levels are measured against the previous session's close and reset daily. The intent is to interrupt a disorderly decline and give participants time to assess rather than to prevent the market from falling.
Limit up-limit down
Individual securities have price bands computed from a rolling reference price. A quote that would take price outside the band triggers a limit state, and if it does not resolve within a short period the security is halted for five minutes.
- The band width depends on the security's price and on whether it is in a broad index.
- Bands are wider at the open and close, when volatility is structurally higher.
- The mechanism was introduced after a disorderly session in which many securities traded at implausible prices.
- It affects thin securities far more often than large ones, which is where the bands are proportionally tightest.
- 1Price moves toward the bandComputed from a rolling reference price
- 2A limit stateQuotes outside the band are not permitted
- 3It does not resolveA five-minute halt follows
- 4Reopening auctionAt whatever price balances the accumulated orders
News and regulatory halts
| Type | Reason | Typical duration |
|---|---|---|
| News pending | The company has material news to release | Minutes to hours |
| Volatility | A limit up-limit down trigger | Five minutes |
| Regulatory | Concerns about the adequacy of public information | Up to ten business days |
| Operational | An exchange or system issue | Varies |
The third row is the one that matters most for anything unfamiliar. A regulatory trading suspension can last ten business days, and securities frequently reopen far below where they were suspended.
What a halt does to a position
For the duration of a halt there is no exit at any price. Stops do not execute, orders rest unfilled, and the position is held through whatever the reopening produces. That is a specific risk that no position sizing based on a stop level accounts for.
It is also why halts cluster around exactly the events that make an exit most desirable. The mechanism is triggered by disorderly movement, which is the condition in which a holder most wants to act.
The reopening auction
A halt ends with an auction rather than with continuous trading resuming. Orders accumulate during the pause, and the reopening price is whichever price maximises the volume that can be matched from them.
- Orders can be entered and cancelled during the halt, so the book being auctioned is built while nobody can trade.
- Indicative prices are published during the pause and can move substantially before the reopening.
- The reopening price is frequently well beyond the level at which the halt was triggered.
- A security can halt again immediately if the reopening move is large enough to breach the band a second time.
The last item is the mechanism behind a sequence of consecutive halts on a single security, which occurs regularly on news. Each pause allows orders to accumulate, and each reopening moves far enough to trigger the next.
For a position held through one, the consequence is that the exit price is set by an auction rather than by anything resembling a continuous market, and no stop order participates in the way it would in ordinary trading.