How Do Stock Market Circuit Breakers Work?
Trading halts are designed to give investors a chance to breathe when things get ugly. Here's how they function.
U.S. stocks had gone more than 20 years without a market-wide trading halt. We've now tripped the so-called circuit breakers two times in four days.
On Monday, March 9, the S&P 500 fell 7% within minutes of the open, triggering a market-wide trading halt for the first time since 1997. Thursday morning's plunge of more than 7% also tripped a circuit breaker.
Circuit breakers were first introduced after the Black Monday crash of October 1987. The Dow dropped almost 23% in a single session, which stands as a record to this day.
From just $107.88 $24.99 for Kiplinger Personal Finance
Become a smarter, better informed investor. Subscribe from just $107.88 $24.99, plus get up to 4 Special Issues
Sign up for Kiplinger’s Free Newsletters
Profit and prosper with the best of expert advice on investing, taxes, retirement, personal finance and more - straight to your e-mail.
Profit and prosper with the best of expert advice - straight to your e-mail.
Circuit breakers are intended to curb panic selling. Like calling a timeout in sports, a temporary pause in trading allows market participants to catch their breath, though it doesn't necessarily keep stocks from declining once trading resumes.
How Circuit Breakers Work
There are three levels of circuit breakers tied to how steeply the market declines:
- A Level 1 market-wide circuit breaker is tripped if the S&P 500 falls 7% from its previous close.
- A Level 2 circuit breaker comes into effect when the market plunges 13%.
- A Level 3 circuit breaker kicks in if the market tanks 20%.
A Level 1 or Level 2 breach halts trading for a minimum of 15 minutes. A Level 3 rout halts trading for the remainder of the trading day.
Level 1 and Level 2 circuit breakers can be triggered between 9:30 a.m. and 3:25 p.m. Eastern. A Level 3 breach can be triggered at any time.
Individual stocks also have circuit breakers, with the trigger levels determined by the price of the stock.
The circuit breakers have worked as intended this week, in that they've given traders a chance to at least catch up as markets tumble on the growing COVID-19 pandemic. Given that the outcome of this crisis is impossible to price in at this point, don't be shocked if we trip circuit breakers repeatedly in the sessions ahead.
Profit and prosper with the best of Kiplinger's advice on investing, taxes, retirement, personal finance and much more. Delivered daily. Enter your email in the box and click Sign Me Up.

Dan Burrows is Kiplinger's senior investing writer, having joined the publication full time in 2016.
A long-time financial journalist, Dan is a veteran of MarketWatch, CBS MoneyWatch, SmartMoney, InvestorPlace, DailyFinance and other tier 1 national publications. He has written for The Wall Street Journal, Bloomberg and Consumer Reports and his stories have appeared in the New York Daily News, the San Jose Mercury News and Investor's Business Daily, among many other outlets. As a senior writer at AOL's DailyFinance, Dan reported market news from the floor of the New York Stock Exchange.
Once upon a time – before his days as a financial reporter and assistant financial editor at legendary fashion trade paper Women's Wear Daily – Dan worked for Spy magazine, scribbled away at Time Inc. and contributed to Maxim magazine back when lad mags were a thing. He's also written for Esquire magazine's Dubious Achievements Awards.
In his current role at Kiplinger, Dan writes about markets and macroeconomics.
Dan holds a bachelor's degree from Oberlin College and a master's degree from Columbia University.
Disclosure: Dan does not trade individual stocks or securities. He is eternally long the U.S equity market, primarily through tax-advantaged accounts.
-
January Fed Meeting: Live Updates and CommentaryThe January Fed meeting is a key economic event, with Wall Street waiting to see what Fed Chair Powell & Co. will do about interest rates.
-
7 Ways to Kick Off an Estate Planning Talk With Your ParentsIt can be hard for aging parents to discuss estate plans — and for adult kids to broach the topic. Here are seven questions to get the conversation started
-
4 Reasons Why the Dollar Remains the World HeavyweightThe dollar may have taken a beating lately, but it's unlikely to be overtaken as the leading reserve currency any time soon. What's behind its staying power?
-
Nasdaq Leads Ahead of Big Tech Earnings: Stock Market TodayPresident Donald Trump is making markets move based on personal and political as well as financial and economic priorities.
-
Nasdaq Adds 211 Points as Greenland Tensions Ease: Stock Market TodayWall Street continues to cheer easing geopolitical tensions and President Trump's assurances that there will be no new tariffs on Europe.
-
Dow Soars 588 Points as Trump Retreats: Stock Market TodayAnother up and down day ends on high notes for investors, traders, speculators and Greenland.
-
If You'd Put $1,000 Into UPS Stock 20 Years Ago, Here's What You'd Have TodayUnited Parcel Service stock has been a massive long-term laggard.
-
Dow Dives 870 Points on Overseas Affairs: Stock Market TodayFiscal policy in the Far East and foreign policy in the near west send markets all over the world into a selling frenzy.
-
Small Caps Can Only Lead Stocks So High: Stock Market TodayThe main U.S. equity indexes were down for the week, but small-cap stocks look as healthy as they ever have.
-
How the Stock Market Performed in the First Year of Trump's Second TermSix months after President Donald Trump's inauguration, take a look at how the stock market has performed.
-
Dow Adds 292 Points as Goldman, Nvidia Soar: Stock Market TodayTaiwan Semiconductor's strong earnings sparked a rally in tech stocks on Thursday, while Goldman Sachs' earnings boosted financials.