August 2023. The rupee had been under sustained pressure. An unexpected policy announcement came mid-session. Within forty minutes, the KSE-100 had shed nearly 1,200 points. Then something happened that confused thousands of retail investors: trading halted. Screens froze. You couldn't sell - or buy - anything.
If you've been investing on the PSX for any length of time, you've likely hit this wall. Your brokerage app stops accepting orders. The price on your screen won't move. And if you're new to this, it's terrifying.
It's not a glitch. It's a circuit breaker and understanding exactly when and how they trigger is critical knowledge for any PSX investor, especially if you're holding ETFs.
What is a Circuit Breaker?
A circuit breaker is a pre-programmed automatic halt in trading. It's the PSX's equivalent of a fire suppression system: when a certain threshold of heat is detected (extreme price movement), it kicks in to stop things from getting worse before rational participants can reassess.
The logic is behavioral, not technical. During a market panic, human psychology can cause prices to overshoot their rational equilibrium dramatically. By briefly suspending trading, circuit breakers give investors time to breathe, read actual news, talk to their brokers, and make a more considered decision rather than a panic-driven one.
Two Types of Circuit Breakers on the PSX
1. Individual Security Circuit Breakers: The ±7.5% Rule
For every stock and ETF listed on the PSX, a maximum daily price movement is enforced. The limit is ±7.5% or PKR 1.00 from the previous session's closing price, whichever is greater.
Let's make this concrete with real PSX examples:
Example A - Small ETF: ACIETF closes at PKR 8.50 on Monday.
- 7.5% of PKR 8.50 = PKR 0.64 - which is less than PKR 1.00, so the PKR 1.00 floor applies.
- Upper limit on Tuesday: PKR 9.50
- Lower limit on Tuesday: PKR 7.50
Example B - Larger ETF: NITGETF closes at PKR 25.00 on Monday.
- 7.5% of PKR 25.00 = PKR 1.875 - which is greater than PKR 1.00, so the percentage applies.
- Upper limit on Tuesday: PKR 26.875
- Lower limit on Tuesday: PKR 23.125
Once the price hits the upper or lower limit, the security is said to be locked. Trading can technically continue at that exact limit price, but in practice, liquidity collapses. If a stock or ETF is locked at the lower limit - what traders call a lower lock - it means everyone who wants to sell has hit the floor price, but barely anyone wants to buy at that level. Your sell order will sit unfilled, potentially for the entire session.
WARNING A lower-lock situation in an ETF is not a permanent loss of value. It's a trading halt, not a fundamental event. The underlying stocks inside the ETF continue to trade and have value. Once the next session opens, normal trading resumes and the price can reflect the true NAV again - unless multiple consecutive lower locks occur during an extended market crisis.
2. Market-Wide Circuit Breaker: The 5% KSE-30 Rule
When the panic isn't isolated to a single stock but has infected the entire market, a different circuit breaker applies.
If the KSE-30 index falls by 5% from its previous closing value at any point during the trading session, the PSX triggers a Market Halt - a full suspension of trading across all equities, all ETFs, and all other securities listed on the exchange.
This halt lasts 45 minutes.
During those 45 minutes, no orders can be placed or matched. The PSX essentially forces a cooling-off period for the entire market. When trading resumes, prices are wherever buyers and sellers agree to transact - circuit breakers reset for the remainder of that session based on the last traded prices.
What Circuit Breakers Mean Specifically for ETF Investors
ETFs add a layer of complexity when circuit breakers hit, because of the relationship between the ETF's market price and the underlying stocks it holds.
Scenario: Two of MIIETF's heavy-weight stocks hit their 7.5% lower lock simultaneously.
With two illiquid, locked underlying stocks in the basket, the ETF's Authorized Participant can no longer accurately price or execute the creation-redemption mechanism. They don't know exactly what those two stocks are "worth" because no trades are going through. As a result:
- The Authorized Participant may pause their activity, widening the ETF's premium/discount to NAV.
- The ETF's Market Maker may widen their bid-ask spread dramatically to protect themselves from the uncertainty.
- If selling pressure on the ETF itself is heavy enough, the ETF may hit its own 7.5% lower limit lock, even if the underlying stocks inside it haven't all locked individually.
This cascade effect is why ETF prices can look strange during market stress - they're reflecting not just the underlying value, but the uncertainty in the valuation process itself.
What Should You Actually Do When a Circuit Breaker Hits?
The worst thing you can do is panic. And the second-worst thing is to immediately queue a market order for the moment trading resumes. Here's a more sensible approach:
- Check the news - is this a temporary panic or a structural market event? A rate decision, an FBR circular, a one-off political development? Context matters.
- Check the iNAV - the PSX portal will still be showing the Indicative NAV based on the current prices of the underlying stocks. Use this to understand the true fair value of your ETF, independent of the market price chaos.
- Use a limit order, not a market order - when trading resumes, liquidity is often thin in the first few minutes. A market order in a thin book can execute at a terrible price. A limit order set near the iNAV protects you.
- Consider your time horizon - if you're a long-term investor and the underlying ETF fundamentals haven't changed, a lower-lock day often presents a buying opportunity rather than a reason to sell.
The Bottom Line
Circuit breakers are frustrating in the moment but they exist because markets without them can and do crash to absurd levels in minutes through pure panic mechanics. For long-term PSX investors, they are almost always noise rather than signal. Understanding how they work lets you stay rational when everyone else isn't.
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This article is for educational and informational purposes only. It does not constitute investment advice. Always conduct your own due diligence and consult a qualified financial advisor before making any investment decisions. All data sourced from PSX, MUFAP, and fund factsheets. Past performance is not indicative of future results.
Dr. Faisal Shahzad
Chief Investment Strategist
Dr. Faisal Shahzad holds an MBA from Innsbruck, Austria, and has spent over a decade navigating complex financial markets. He specializes in Exchange Traded Funds (ETFs) and brings extensive, practical knowledge of both international markets and the Pakistan Stock Exchange (PSX).
Expertise: 15+ Years of experience in ETFs, both internationally and on the PSX.