A trading circuit breaker is an automatic pause in trading that kicks in when prices move too far, too fast. In U.S. stocks there are two kinds: market-wide halts that trigger when the S&P 500 falls 7%, 13% or 20% from the prior close, and single-stock pauses that trigger when one stock leaves its price band. A kill switch is a different tool: it stops one trader's or one firm's own activity. This guide covers the exact numbers, what happens during a halt, and how to build a personal circuit breaker so your own rules do what the exchange's rules do for the market.
TL;DR
- Market-wide circuit breakers halt U.S. stock trading when the S&P 500 drops 7% (Level 1), 13% (Level 2) or 20% (Level 3) from the previous day's close.
- Level 1 and Level 2 halts last at least 15 minutes. Level 3 halts trading for the rest of the day.
- Single stocks have their own Limit Up-Limit Down (LULD) bands, and a stock that stays outside its band for 15 seconds gets a pause.
- A kill switch is not a circuit breaker. It is a control that cancels orders and blocks new ones for one participant.
- You can copy the idea for your own account with a daily loss limit, a lockout and a stand-aside rule.
Table of Contents
- What a trading circuit breaker is
- Market-wide circuit breakers: the three levels
- Single-stock pauses: Limit Up-Limit Down
- Circuit breaker vs. kill switch
- Do crypto, forex and other markets have circuit breakers?
- Build your own trading circuit breaker
- Perspective
- Put a circuit breaker into your routine
- Common mistakes when markets pause
- A short checklist before each session
- FAQ
- Sources
What a trading circuit breaker is
The idea is simple: when selling or buying becomes disorderly, force a pause so that people can reassess instead of reacting. The SEC's investor guidance describes the modern U.S. system as two layers: market-wide circuit breakers and a Limit Up-Limit Down mechanism for individual securities (SEC Investor Bulletin).
The market-wide version was adopted by all U.S. equity exchanges and FINRA in 2012 as uniform rules meant to slow the effects of extreme price movement through coordinated halts across markets (Federal Register, November 2, 2026). The same document calls the mechanism an automatic safeguard invoked to promote stability during significant stress.
Two things matter for you as a trader:
- The pause is not a prediction. It does not say whether prices will rebound or keep falling.
- It is not personal. It applies to everyone at once, and it will not protect your account from your own bad decisions. That second part is where your own rules come in, covered below.
Market-wide circuit breakers: the three levels
U.S. market-wide circuit breakers (MWCB) trigger when the S&P 500 declines by 7%, 13% or 20% from the prior day's closing price, according to the NYSE's Market-Wide Circuit Breakers FAQ.
| Level | S&P 500 decline from prior close | What happens |
|---|---|---|
| Level 1 | 7% | Trading halts for at least 15 minutes |
| Level 2 | 13% | Trading halts for at least 15 minutes |
| Level 3 | 20% | Trading halts for the rest of the trading day |
The 15-minute minimum for Levels 1 and 2, and the full-day halt at Level 3, come from the same NYSE FAQ.
The 3:25 p.m. rule
Timing matters. Level 1 and Level 2 halts can be triggered before 3:25 p.m. ET. A similar decline at or after 3:25 p.m. will not halt market-wide trading (SEC Investor Bulletin). A Level 3 decline, by contrast, can trigger at any time of day and ends trading for the session (Federal Register).
Each level fires once per day
Each halt level can only be triggered once per trading day. If a Level 1 halt happens and trading resumes, there will be no second Level 1 halt even if the S&P 500 crosses the 7% line again (Cboe MWCB FAQ). That detail surprises many traders: a market can keep falling after the first pause with no new Level 1 stop, so the next safeguard is Level 2 at 13%.
What the halt covers
All National Market System securities are halted when a threshold is breached (Nasdaq). FINRA Rule 6121 backs this up by requiring FINRA to halt trading otherwise than on an exchange in NMS stocks when the major markets initiate market-wide halts (FINRA Rule 6121). So there is no off-exchange loophole for those stocks.
How trading resumes
After a Level 1 or Level 2 halt, NYSE, NYSE Arca and NYSE American run reopening auctions in their primary-listed securities (NYSE FAQ). Expect wide spreads and fast price discovery right after the reopen. If you hold open orders, they may fill at prices you did not expect.
The old thresholds
Before the 2013 revision, the thresholds were 10%, 20% and 30% measured against the Dow Jones Industrial Average (SEC Investor Bulletin). Older articles quoting those numbers are out of date.
What about the "80% rule"?
There is no 80% threshold in the U.S. market-wide system. The figure readers see in search suggestions most likely traces back to the old exchange rule number: the regulatory filing behind U.S. circuit breakers has been known as Rule 80B (Wikipedia). The levels that matter today are 7%, 13% and 20%.
Single-stock pauses: Limit Up-Limit Down
A market-wide halt is rare. A single-stock pause is far more common, and if you trade individual shares you are more likely to meet one.
The LULD mechanism prevents trades in an individual security from happening outside a price band set as a percentage above and below the stock's average price over the preceding five minutes (SEC Investor Bulletin). The SEC approved LULD on May 31, 2012, to replace single-stock circuit breakers triggered by erroneous trades, and implementation began April 8, 2013.
If a stock hits the edge of its band and does not move back inside within 15 seconds, trading in that stock pauses (Investor.gov). The pause normally lasts five minutes, and it can run longer if the reopening auction cannot be priced within its collars because of continuing imbalances (Cornerstone Research).
The price bands
FINRA's Regulatory Notice 13-12 lists the bands (FINRA):
| Stock type | Band |
|---|---|
| Tier 1 NMS stocks (S&P 500, Russell 1000, select ETPs) priced above $3.00 | 5% |
| Tier 2 NMS stocks priced above $3.00 | 10% |
| Stocks priced $0.75 to $3.00 | 20% |
| Stocks priced below $0.75 | The lesser of $0.15 or 75% |
The bands apply during regular hours, 9:30 a.m. to 4:00 p.m. ET, and they double during the last 25 minutes of the day for all Tier 1 stocks and for Tier 2 stocks at or below $3.00 (Investor.gov).
Why this matters for your orders
- A market order in a fast-moving small cap can sit unfilled if the stock is outside its band.
- A stop order can trigger and then fail to fill at the price you pictured.
- A pause is not a safe exit. You still hold the position when trading reopens, and the price can reopen far from where it stopped.
That last point is the practical lesson. An exchange pause protects the market's order, not your P&L.
Circuit breaker vs. kill switch
People searching for a trading kill switch often land on circuit breaker pages, and the two are easy to mix up. The difference is who they protect and who controls them.
- Circuit breakers are market-wide or security-level pauses set by exchanges and regulators.
- Kill switches are participant-, strategy- or firm-specific controls that stop that party's own trading (Global Banking and Finance).
An exchange kill switch, as described in an SEC-filed rule for ISE, lets a member send a message to the trading system to promptly cancel orders and restrict new orders until re-entry is enabled (SEC filing, ISE Rule 711).
In automated trading, one design lesson stands out: a kill switch works best outside the strategy, in a separate gatekeeper every order passes through, because a bug that breaks a strategy can also break its own self-checks (Quant Memo). The same lesson applies to a discretionary trader. If your only safeguard is your own judgment in the moment, it fails exactly when you are tilted. Put the rule somewhere your emotions cannot edit it.
Do crypto, forex and other markets have circuit breakers?
The numbers above apply to U.S. stocks. Crypto and forex are structured differently, and many venues set their own halt, price-limit or liquidation rules. Read each venue's published rules before you trade there, and do not assume a pause will arrive to save a position. If you trade crypto, forex and stocks, you effectively need your own circuit breaker, because the market's may not exist for the instrument you hold.
Build your own trading circuit breaker
The exchange version fires on a measured threshold, pauses everyone for a fixed time, and reopens in an orderly way. You can copy all three features.
1. Set a measurable trigger
Pick numbers before the session starts, never during it. Common triggers:
- A daily loss limit, such as a fixed percentage of account equity.
- A maximum number of consecutive losing trades.
- A maximum number of trades per day.
- A breach of your planned risk on a single trade.
The trigger should be a number you can check in a second. "I feel off" is useful, but it is not a trigger.
2. Define the pause
The exchange pauses for a set time, not "until it feels better." Decide your pause in advance: stop for the rest of the day, or a fixed cooling-off period. Our guide to preconfiguring a trading lockout shows templates and platform checks so the lockout is already in place when you need it.
3. Plan the reopening
Markets reopen with an auction, not a free-for-all. Your return to trading should be just as structured. Start with smaller size, require a full checklist before the first trade, and do not try to win back the loss in one trade. The reentry routine after a stop walks through a short reset, and a pre-trade validation checklist keeps the first trade back from being an impulse.
4. Size for the halt you cannot control
Market halts and gaps are where position size matters most. If a stock reopens far below where it paused, a stop order will not save you from the gap. Smaller size, defined risk per trade and sensible leverage are the only protections that work before the event. For a plain-language list of controls to set up first, see these risk controls for newer traders.
A worked example
Suppose you trade with a $10,000 account and set a daily circuit breaker at 2% equity loss, which is $200. You risk 0.5% ($50) per trade. Four full stop-outs reach your limit. After the fourth loss, the day is done: you close the platform or activate your lockout, and you review the trades the next morning. Compare that with having no limit: the fifth, sixth and seventh trades are usually the ones taken in frustration, at larger size, with weaker setups. The numbers here are an illustration of the mechanism, not a recommendation for your account.
Perspective
Exchanges built circuit breakers because they know a simple truth: people and systems make their worst decisions at speed, under stress. We built Discipline AI around the same idea, applied to the individual trader.
Sentinel, our intelligence and research system, looks at market structure, liquidity events, volatility and market regimes, and helps you see when conditions call for caution or standing aside. Standing aside is a decision, and often the best one. A market-wide halt only happens once in a long while. Your own bad day can happen any week.
That is why we put risk planning, position sizing, paper trading and trade journaling in the same place as the trade setups. You plan the risk before the trade, you practice without capital when you are testing a new idea, and you review outcomes honestly afterward. We emphasize measurable evidence over predictions, and we do not promise profitable trades. What we do offer is a structure that makes disciplined behavior easier to repeat.
If you take one thing from this article, take this: write your circuit breaker down while you are calm, then let a tool enforce it when you are not.
Tony
Put a circuit breaker into your routine
Discipline AI is a mobile app for iOS and Android that brings risk planning, stand-aside guidance, paper trading and automated trade journaling into one workflow. It is built to help you plan position size and leverage before you enter, spot unfavorable conditions, and learn from completed trades through performance analytics and AI Trade Autopsies. It does not guarantee profits, and it will not replace your own judgment.
The Pro plan is $8.99 per month, $79.99 per year, or $199.99 one-off. See the details on the pricing page. If you want a structured course on trading behavior, The Disciplined Trader is available for a one-off $79.
Common mistakes when markets pause
- Treating the pause as a buy signal. A halt says nothing about direction. Wait for the reopening and for your own setup to appear.
- Placing market orders into the reopen. Spreads can be wide. Limit orders give you control over price, though they may not fill.
- Assuming one halt means the worst is over. Each market-wide level fires once per day, and a deeper level can still follow.
- Revenge trading after a stop. This is the personal version of a Level 3 halt: when the day is over, it is over.
- Ignoring your own data. A journal reveals which hours, instruments and setups you lose in most. If you are unsure which tools can hold you accountable, compare these trader accountability tools.
A short checklist before each session
- Do I know today's maximum loss in dollars?
- Do I know my maximum number of trades?
- Is a lockout or stand-aside rule set up before the open?
- Do I know the major scheduled events and the hours when spreads widen?
- Does each setup have a defined entry, stop and size before I click?
- Do I know what I will do after the first loss, and after the third?
If you cannot answer all six, trade smaller or practice in paper mode until you can.
FAQ
What triggers a stock market circuit breaker?
A market-wide breaker triggers when the S&P 500 falls 7%, 13% or 20% from the prior day's close. A single-stock pause triggers when a stock reaches its price band and does not return within 15 seconds (Investor.gov). The bands depend on the stock's tier and price.
How long does a circuit breaker halt last?
Level 1 and Level 2 market-wide halts last at least 15 minutes. A Level 3 halt lasts for the rest of the trading day (NYSE FAQ). Single-stock pauses usually run five minutes and can extend if the reopening auction cannot be priced.
Is a trading kill switch the same as a circuit breaker?
No. A circuit breaker pauses a market or a security for everyone. A kill switch is a control that stops one participant's own trading by canceling open orders and blocking new ones. Individual traders can copy the idea with a daily loss limit and a lockout.
Can a circuit breaker trigger late in the day?
Level 1 and Level 2 halts cannot trigger at or after 3:25 p.m. ET. A Level 3 halt can trigger at any time (SEC). Single-stock bands also widen in the last 25 minutes of the session for many stocks.
Sources
- Stock Market Circuit Breakers, Investor.gov
- Investor Bulletin: New Measures to Address Market Volatility, SEC
- Market-Wide Circuit Breakers FAQ, NYSE
- U.S. Market Wide Circuit Breaker FAQ, Cboe
- Market-Wide Circuit Breakers: What You Need to Know, Nasdaq
- FINRA Rule 6121
- FINRA Regulatory Notice 13-12
- Federal Register, November 2, 2026
- March Trading Halts May Complicate Securities Class Actions, Cornerstone Research
- The Truth About Financial Kill Switches, Global Banking and Finance
- ISE Rule 711 filing, SEC
- Kill Switches and Circuit Breakers, Explained, Quant Memo
- Trading curb, Wikipedia