Glossary · PSX Mechanics
Circuit Breaker
A regulatory mechanism that temporarily halts trading in a security or the entire market when prices move beyond a defined threshold. On the PSX, individual stocks generally have upper and lower price limits of 10% or Re 1, whichever is higher, per session to prevent extreme volatility.
01—What is Circuit Breaker?
The definition — and what it means in practice.
A circuit breaker is a regulatory control that temporarily stops trading in a single security or, in some markets, the whole exchange when prices move beyond a set limit. The aim is to slow down extreme moves and allow time for orders and information to be processed. Circuit breakers can take the form of a timed halt or a price limit that prevents trades outside an allowed range.
For investors, circuit breakers affect whether your order can execute at the price you want and how quickly you can enter or exit a position during fast markets. When a limit is hit, liquidity can dry up and spreads can widen, so market orders may fill at unexpected levels once trading resumes or when prices move back within limits. They also influence intraday strategies and risk controls.
If a PSX share closed at Rs 100, it generally cannot trade above Rs 110 or below Rs 90 in that session (or Re 1, if higher).
- A circuit breaker is designed to curb disorderly trading during sharp price moves.
- It may halt trading or impose a trading band that blocks prints outside set limits.
- When limits are reached, execution can be delayed and liquidity may worsen.
- Your order type matters: market orders can behave unpredictably around halts/limits.
- Circuit breakers reduce intraday extremes, but they do not remove investment risk.
02—How circuit breaker works on the PSX
The Pakistan-specific rules, conventions, and numbers.
On the Pakistan Stock Exchange (PSX), most equities have daily price limits around the last day close price (LDCP). The limit is generally ±10% or Re 1 (whichever is higher) per session. When the limit is reached, trades cannot occur beyond that band, effectively acting as a circuit breaker at the individual-stock level.
A PSX investor most commonly encounters circuit breakers when a stock becomes a “top gainer” or “top loser” and hits its upper or lower limit. In that situation, orders may queue at the limit price and execution depends on whether opposite-side orders appear. Because trades clear through NCCPL and settle on T+1, a limit-hit day affects trading activity and order management, but it does not change the standard settlement cycle.
03—Common misconceptions
Where investors most often get this wrong.
A circuit breaker means the price will reverse after the halt or limit.
It only slows or constrains trading. Price direction afterwards still depends on supply, demand, and new information when trading continues within allowed limits.
If a stock is at upper limit, buying will definitely execute.
Execution requires sellers. At limits, orders often stack on one side, so your order may remain unfilled until liquidity appears.
Circuit breakers eliminate the risk of large losses.
They can reduce intraday extremes, but losses can still accumulate over multiple sessions or via gaps between sessions within the permitted limits.
04—Using circuit breaker on BSL
Where this term shows up across the platform — with live data.
- See which shares closed locked at their band with Upper & Lower Cap Stocks.
- Check current movers and limit-hit names via Top Gainers.
- Track sharp down-moves and potential lower-limit pressure using Top Losers.
- Use the Stock Screener to filter shares by liquidity and other basics before placing orders.
- Learn how execution works by reviewing Order Book.
05—Frequently asked questions
What investors ask about circuit breaker on the PSX.
Frequently Asked Questions
On the PSX, a circuit breaker is typically implemented as a daily price limit for most equities. Trading is constrained to a band around the last day close price (LDCP), generally ±10% or Re 1, whichever is higher, for the session.
For most listed shares, the allowed trading range for the session is set around the LDCP. The band is generally plus or minus 10%, or Re 1, whichever produces the larger absolute move from the LDCP.
You can usually place orders, but execution depends on available opposite-side liquidity within the permitted band. If a stock is pinned at the upper or lower limit, orders may queue and remain unfilled until matching interest appears.
No. PSX equity trades clear through NCCPL and typically settle on T+1 (one business day). A circuit breaker changes what prices can trade during the session, not the standard settlement cycle.
Not always. A trading halt is a stoppage of trading, usually for a defined period or condition. A circuit breaker is the broader concept and can be implemented either as a halt or as a price limit that prevents trades beyond a set range.
06—Related terms
Keep building the picture.
The price at which a stock finished trading on the previous business day. Serves as the reference point for calculating the day's allowable price movement under the PSX's circuit breaker rules.
A temporary suspension of trading in a security ordered by the PSX. Can be triggered by a pending announcement, unusual price activity, or regulatory action.
The degree of price fluctuation in a security or market over a given period. High volatility means prices move sharply and unpredictably. Low volatility indicates steadier, more predictable movement.
An instruction to buy or sell a security at a specific price or better. The order is only executed if the market reaches the specified price, giving the investor control over the execution price.
A real-time electronic record of all buy and sell orders for a security on the exchange, showing prices and quantities at each level.
The ease with which a security can be bought or sold without significantly affecting its price. High-liquidity stocks have large trading volumes and narrow bid-ask spreads.
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