Trading Halt Reason Codes Explained
When a stock is halted, the exchange assigns a reason code that explains why trading was paused. Below is a complete glossary of halt reason codes used by NASDAQ, NYSE, and other U.S. exchanges.
Price Volatility
LUDP Limit Up-Limit Down Pause
What it means: The stock's price moved outside its LULD price band, triggering an automatic 5-minute trading pause. LULD bands are calculated as a percentage above and below a reference price and are designed to prevent extreme short-term volatility.
How long it lasts: Typically 5 minutes. Trading resumes automatically unless extended by the exchange.
Common for: Volatile small-cap and mid-cap stocks experiencing rapid price movement, often around earnings releases, FDA decisions, or breaking news.
LUDS Limit Up-Limit Down Pause (Straddle)
What it means: Similar to LUDP, but triggered when the National Best Bid or Offer straddles the LULD price band (the bid is below the lower band while the offer is above it). This condition indicates extreme price uncertainty.
How long it lasts: Typically 5 minutes, same as a standard LUDP pause.
Common for: Thinly traded securities where the bid-ask spread is wide enough to cross the LULD band boundaries.
Regulatory / News
T1 Halt — News Pending
What it means: The exchange has halted trading because material news is pending for the company. This allows all investors to receive and evaluate the news before trading resumes, ensuring a fair and orderly market.
How long it lasts: Variable — from minutes to hours. The exchange resumes trading once it determines the news has been adequately disseminated. Some T1 halts can last overnight if news is expected after market hours.
Common for: Earnings announcements, mergers and acquisitions, FDA approvals, significant contract awards, or any material non-public information about to be released.
T2 Halt — News Released
What it means: The material news has been released, but the exchange is keeping the halt in place briefly to allow investors time to digest the information before trading resumes.
How long it lasts: Usually 5–30 minutes after news release. The exchange lifts the halt once it believes the market has had adequate time to process the information.
Common for: Follows a T1 halt once the pending news has been publicly released. Often seen with earnings results, clinical trial data, or M&A announcements.
T12 Halt — Additional Information Requested
What it means: The exchange has requested additional information from the company before trading can resume. This typically occurs when the initial news release was incomplete, unclear, or raised additional questions.
How long it lasts: Variable — can last hours or extend overnight. Trading resumes once the exchange is satisfied with the additional information provided.
Common for: Situations where a company's press release is ambiguous, when regulatory filings contain unexpected disclosures, or when the exchange identifies potential compliance concerns.
H10 SEC Trading Suspension
What it means: The U.S. Securities and Exchange Commission (SEC) has suspended trading in the security. This is a serious regulatory action that can last up to 10 business days.
How long it lasts: Up to 10 business days. The SEC may extend the suspension if warranted.
Common for: Suspected fraud, manipulation, lack of current public information about the company, or questions about the accuracy of publicly available information.
Compliance
H4 Non-Compliance Halt
What it means: Trading has been halted because the company is not in compliance with the exchange's listing requirements. This can include failure to file required financial statements, falling below minimum share price or market cap thresholds, or other listing standard violations.
How long it lasts: Indefinite — trading resumes only when the company returns to compliance or the exchange takes further action (such as delisting).
Common for: Companies that miss SEC filing deadlines, fall below the $1 minimum bid price for extended periods, or fail to maintain required levels of shareholders' equity.
Market-Wide Circuit Breakers
MWC1 Market-Wide Circuit Breaker Level 1 (7% Drop)
What it means: The S&P 500 has declined 7% from the previous day's closing price, triggering a market-wide trading halt across all U.S. equity exchanges.
How long it lasts: 15 minutes. If triggered after 3:25 PM ET, trading is not halted.
Common for: Major market sell-offs driven by economic crises, geopolitical events, or systemic financial stress. Last triggered on March 9, 2020, during the COVID-19 market crash.
MWC2 Market-Wide Circuit Breaker Level 2 (13% Drop)
What it means: The S&P 500 has declined 13% from the previous day's close. This is a more severe market event indicating widespread panic selling.
How long it lasts: 15 minutes. If triggered after 3:25 PM ET, trading is not halted.
Common for: Extremely rare events. A Level 2 circuit breaker represents a severe market crisis beyond a typical correction.
MWC3 Market-Wide Circuit Breaker Level 3 (20% Drop)
What it means: The S&P 500 has declined 20% from the previous day's close. This is the most severe circuit breaker level.
How long it lasts: Trading is halted for the remainder of the trading day, regardless of what time it is triggered.
Common for: Catastrophic market events. A Level 3 circuit breaker has never been triggered under the current system.
IPO / Direct Listing
IPO1 IPO/Direct Listing — Not Yet Trading
What it means: The security is a new IPO or direct listing that has not yet begun trading. The exchange is in the process of establishing an opening price through the IPO auction mechanism.
How long it lasts: Until the exchange completes the price discovery process and opens the stock for trading, typically within the first few hours of the listing day.
IPOQ IPO/Direct Listing — Order Entry Period
What it means: The exchange has entered the order entry period for a new IPO or direct listing. Market participants can submit orders, but matching and trading have not yet begun.
How long it lasts: Variable — depends on order flow and the designated market maker's price discovery process.
IPOE IPO/Direct Listing — Released to Trading
What it means: The exchange has completed price discovery for the IPO or direct listing, and the security has been released for regular trading.
How long it lasts: This is a resumption code — it indicates the halt is over and normal trading has begun.
How Trading Halts Work
Trading halts are temporary suspensions of trading activity for a specific security or across entire markets. They are a fundamental market safety mechanism designed to ensure fair and orderly trading by giving all investors equal access to material information.
When a halt is initiated, no buy or sell orders can be executed for the affected security. Existing orders remain in the order book but are not matched. Once the halt is lifted, trading resumes — often with a brief auction period to establish a fair opening price.
Halts are issued by the listing exchange (NASDAQ, NYSE) or by the SEC. The exchange communicates halts in real time through the UTP (Unlisted Trading Privileges) system, which Stock Titan monitors directly via NASDAQ's data feed.
Halt vs. Suspension vs. Circuit Breaker
Trading Halt
A temporary pause initiated by the listing exchange, typically for news dissemination (T1, T2) or compliance issues (H4). Affects a single security. Duration varies from minutes to days.
Volatility Pause
An automated, time-limited suspension triggered by the LULD mechanism when a stock's price moves too quickly (LUDP, LUDS). Typically lasts exactly 5 minutes and resumes automatically.
Circuit Breaker
A market-wide halt triggered when the S&P 500 drops by preset thresholds (7%, 13%, 20%). Affects ALL securities across all U.S. exchanges simultaneously. Designed to prevent market-wide panic.