Trading Halts: What Are They and Why Do They Happen?

A trading halt is a temporary suspension of trading in a security or across an entire market. In the fast-moving world of financial markets, trading halts serve as emergency brakes — pausing activity to prevent panic, allow information to spread fairly, or fix technical problems before trading resumes.

For traders and investors, a trading halt can be alarming — especially if you are holding a position and suddenly cannot exit it. Understanding why halts happen, how long they last, and what you should do when one occurs is essential knowledge for anyone active in stock, forex, or cryptocurrency markets.

This guide covers everything: the definition of a trading halt, who can trigger one, the main causes, how circuit breakers work, how long halts last, how they differ from price limits, and how trading halts compare across different markets including US exchanges, the Tehran Stock Exchange, and the forex market.

What Is a Trading Halt?

A trading halt is a temporary pause in the buying and selling of a specific security or group of securities on one or more exchanges. During a halt, no orders can be placed, matched, or executed. Existing orders in the order book may be cancelled or held, depending on the exchange's rules.

Trading halts can apply to:

• A single stock (e.g. following a major corporate announcement)
• An entire sector or index
• An entire exchange or market (market-wide circuit breaker)

The duration can range from a few minutes to several days. In rare cases — such as the closure of US exchanges following the September 11, 2001 attacks — a halt can last multiple trading sessions.

Who Can Halt Trading?

Trading halts can be initiated by several different authorities depending on the market:

In practice, the vast majority of trading halts on major exchanges are initiated automatically by circuit breaker systems — not by human decision-makers. This makes the system faster and removes political considerations from the process.

Why Does Trading Get Halted? — Main Causes

1. Pending Material News

The most common cause of a single-stock trading halt. When a company is about to release information that could materially affect its share price — a merger announcement, earnings restatement, FDA drug approval, or major litigation outcome — trading is halted to ensure all investors receive the information simultaneously before reacting.

This prevents informed insiders from trading before the public announcement, maintaining market fairness. These halts are typically brief — lasting 30 minutes to a few hours — and are lifted once the news is publicly disseminated.

2. Extreme Volatility — Circuit Breakers

Market-wide circuit breakers are automatic mechanisms that pause trading when a major index falls beyond a set threshold within a single session. In the United States, the S&P 500 circuit breaker levels are:

Circuit breakers were introduced after the 1987 Black Monday crash and have been triggered several times since — most notably in March 2020 during the COVID-19 market panic, when US markets hit Level 1 circuit breakers on four separate days.

3. Technical Glitches

Technology failures — exchange system outages, software bugs, data feed errors, or cybersecurity incidents — can trigger trading halts. The 2010 Flash Crash, during which the Dow Jones fell nearly 1,000 points in minutes before recovering, led to the introduction of individual stock circuit breakers (Limit Up-Limit Down rules) in addition to market-wide breakers.

4. Regulatory Investigation

Regulators such as the SEC (USA) or FCA (UK) can halt trading in a stock for up to 10 trading days if they suspect fraud, manipulation, or that investors lack adequate information to make informed decisions. These halts are typically announced publicly and can last significantly longer than volatility-triggered halts.

5. Voluntary Company Request

A listed company can request a voluntary trading halt — typically ahead of a major announcement — to prevent disorderly trading based on rumour or leaked information. The company requests the halt from the exchange and provides an expected timeline for resumption.

How Long Do Trading Halts Last?

The duration of a trading halt depends entirely on its cause:

For most retail traders, the most commonly encountered halts are brief — under an hour — and related to news announcements. The longer and more serious halts (regulatory investigations, multi-day closures) are rare and typically affect specific securities rather than the entire market.

Trading Halt vs Up/Down Price Limits — What Is the Difference?

These two mechanisms are frequently confused but function very differently:

Price limits are particularly common in Asian markets and on the Tehran Stock Exchange, where the TSE imposes a ±5% daily price limit on most listed shares. This means a stock cannot move more than 5% up or down from its previous closing price in a single session — but trading continues within that range. For more detail on how price limits work on the Iranian market, see our guide on investing in the Tehran Stock Exchange.

Trading Halts in the Forex Market

One of the key advantages of the forex market over stock markets is that forex does not have circuit breakers or trading halts in the traditional sense. The forex market is decentralised — there is no single exchange that can pause activity — so trading continues 24 hours a day, five days a week across global financial centres.

However, forex traders do encounter situations that function similarly to trading halts:

• Weekend gaps: Forex markets close Friday at 22:00 GMT and reopen Sunday at 22:00 GMT. Major news events over the weekend can cause prices to gap significantly at open — effectively creating an information asymmetry similar to a news-driven trading halt.
• Central bank interventions: When a central bank directly intervenes in currency markets (e.g. the Swiss National Bank's surprise franc cap removal in 2015), liquidity can disappear almost instantly — resembling a halt in practice even if not formally declared.
• Broker-side restrictions: Individual forex brokers can restrict trading on specific pairs during extreme volatility — widening spreads to levels that make trading uneconomical, or temporarily removing a pair from the platform entirely.
• Major news events: NFP (Non-Farm Payrolls), central bank rate decisions, and geopolitical shocks can cause spreads to widen dramatically in the seconds surrounding the announcement — discouraging trading without formally halting it.

What Should You Do When a Trading Halt Occurs?

1. Do not panic. Most halts are brief and the stock or market resumes trading within minutes to hours. Panic decisions made based on incomplete information during a halt typically lead to poor outcomes.
2. Check the reason. Most major exchanges publish halt notifications in real time on their websites. The reason for the halt determines how you should respond — a brief news halt is very different from a regulatory fraud investigation.
3. Avoid placing orders immediately at resumption. The first few minutes after a halt resumes are often volatile and have wide spreads. Wait for the initial rush to settle before entering or exiting.
4. Review your stop-loss levels. If the halt was triggered by bad news, the stock may gap down significantly when trading resumes. Ensure your risk parameters are appropriate for this scenario.
5. Do not rely on pre-halt prices. If major news has been released during the halt, the pre-halt price is no longer a reliable reference. Reassess the position based on the new information.

Frequently Asked Questions