Halt (LULD)
A mandatory pause in trading when a stock's price moves too far, too fast. LULD bands are set as a percentage of the prior reference price.
A LULD halt (Limit Up-Limit Down) is a temporary suspension of trading triggered automatically when a stock's price moves outside a defined percentage band from a 5-minute reference price. The bands are narrower for S&P 500 and Russell 1000 stocks (5%) and wider for others (10–20%).
When a stock touches the band and stays there for 15 seconds without trading resuming within the band, a 5-minute trading pause is called. After 5 minutes, trading resumes via an auction — unless the halt extends due to continued extreme conditions.
LULD replaced the old single-stock circuit breakers after the 2010 Flash Crash. It slows momentum panics and squeezes, giving market participants time to reassess. Halts on news or regulatory grounds (SEC investigations, merger announcements) follow a separate process.
Related Terms
After-Hours Trading
Stock trading that occurs after the official 4:00 PM ET close. Lower liquidity and wider spreads; major news like earnings often hits here.
IntermediateCircuit Breaker (Market-Wide)
An exchange-wide trading halt triggered by a sharp S&P 500 drop, pausing all US stock trading to curb panic selling.
AdvancedMarket Maker (Equities)
A firm or individual that continuously quotes buy and sell prices for a stock, providing liquidity and enabling smooth trading.
AdvancedNYSE
The world's largest stock exchange by market capitalization, located at 11 Wall Street in New York City.
BeginnerPre-Market Trading
Trading before the 9:30 AM ET open, typically from 4:00 AM to 9:30 AM ET. Used to react to overnight news, data, and earnings.
IntermediateReverse Stock Split
When a company consolidates shares, reducing the count and raising the price per share proportionally. Often a warning sign.
IntermediateShort Squeeze
A rapid price surge that forces short sellers to cover at a loss, which drives the price even higher in a self-reinforcing feedback loop.
Advanced