Stock halt codes,
explained for traders.
When a U.S. stock stops trading, the exchange publishes a reason code. That code tells you almost everything that matters: whether the pause is a five-minute mechanical reset or an open-ended regulatory problem, and whether your capital is coming back in minutes or in months.
This is the reference we use inside Halt Strategy. Each page covers what triggers the halt, how long it typically lasts, how the security resumes, and what the code implies for a day trader's risk.
All 15 entries reviewed against the exchanges' published sources on . Read the editorial policy for how this is sourced and corrected.
Volatility halts
Automatic, mechanical pauses triggered by price movement. Short, frequent, and the basis of most halt-resume strategies.
Volatility Trading Pause (Limit Up-Limit Down)
LUDP is a five-minute volatility trading pause triggered when a stock trades outside its Limit Up-Limit Down price band.
Volatility Trading Pause — Straddle Condition
LUDS marks a LULD volatility pause caused by a straddle condition, where the price band brackets the market and quoting cannot continue normally.
News halts
Discretionary halts around the release of material information. Open-ended and driven by the catalyst, not the chart.
Regulatory halts
Halts raised by the exchange or the SEC over compliance, disclosure, or filings. Long, and the tail risk of holding small caps.
Halt — Additional Information Requested
T12 means trading is halted because the exchange has requested additional information from the company and is waiting for a response.
Halt — Non-Compliance
H4 means trading is halted because the company is not in compliance with the exchange's listing requirements.
Halt — Filings Not Current
H9 means trading is halted because the company is not current in its required regulatory filings.
Halt — SEC Trading Suspension
H10 means the U.S. Securities and Exchange Commission has suspended trading in the security, halting it across all markets.
Halt — Regulatory Concern
H11 means trading is halted in conjunction with another exchange or regulatory authority acting on a regulatory concern.
Security Deletion
Code D marks the deletion of a security from the exchange, meaning it is no longer listed or quoted there.
Operational halts
Market-mechanics halts: system issues, corporate actions, fund component problems, and new listings.
Halt — Extraordinary Market Activity
T6 means trading is halted because of extraordinary market activity, such as a system malfunction or erroneous orders distorting the market.
Halt — ETF Component Halt
T8 means an exchange-traded fund is halted because trading in the securities or instruments underlying it has been halted.
Halt — Corporate Action
M1 means trading is halted in connection with a corporate action affecting the security, such as a reverse split or reorganization.
IPO Issue Not Yet Trading
IPO1 means a newly listed security has not yet opened for trading and is awaiting its initial cross.
Market-wide halts
Halts that stop every U.S. equity at once, triggered by index-level declines rather than by any single security.
Primary sources
Halt codes and their handling are defined by the exchanges and the SEC. These are the authoritative references:
Halt Strategy is research software, not investment advice, and does not execute trades. Halt procedures are set by the exchanges and regulators and can change; confirm current rules against the primary sources before acting on them. Read the full disclaimer and editorial policy.