Stock halt codes explained
When a stock halts, the exchange publishes a code saying why. The code is the single best predictor of how long the halt will run, and the difference is not small: a volatility pause is measured in minutes, a news-pending halt in hours. Below is every code we have seen, in plain English, with the median time each one actually lasted.
| Code | What it means | Median | Halts seen |
|---|---|---|---|
| LUDP | Volatility Pause (LULD) | 5 min | 393 |
| M | Volatility Trading Pause (LULD) | 5 min | 210 |
| T1 | News Pending | 13 h 10 min | 120 |
| T12 | Additional Information Requested | 4 h 19 min | 12 |
| H11 | Regulatory Concern | not enough data | 2 |
Trading halts: common questions
- What is a trading halt?
- A pause in trading for one stock across every US exchange at once. Nothing executes until the stock reopens, usually through an auction. Halts come with a code that says why, and the code is the best predictor of how long you will be waiting.
- How long does a trading halt last?
- It depends entirely on the code, and the spread is enormous. A volatility pause is over in minutes because it is mechanical. A news-pending halt routinely runs past the closing bell, because it ends when the company releases news rather than when a timer expires.
- What is the difference between a volatility halt and a news halt?
- A volatility halt is triggered automatically when price moves outside a preset band, and it resolves itself. A news halt is requested because material information is coming, and it resolves only once that information is public.
- Where do these halt times come from?
- Our own halt feed. We record the halt and the resume time for every US halt we see, so the medians on these pages are measured rather than quoted from a rulebook. Where we have not captured enough halts under a code, we say so instead of publishing a number.