What does halt code M mean? Volatility Trading Pause (LULD)
A single-stock volatility pause, the same mechanism as LUDP, carried under a different code by the reporting feed.
How long a M halt actually lasts
5 min
median
9 min
9 in 10 within
258
halts seen
156
stocks
Measured from our own halt feed across 204 M halts that published a resume time, 2026-07-20 to 2026-09-09. The median is used rather than the average because halt lengths are heavily skewed, and a handful of long ones would drag a mean somewhere no individual halt has ever been.
What triggers it
The same Limit Up-Limit Down bands. Despite the name it is not market-wide: the market-wide circuit breakers are M1, M2 and M3, and those halt every stock at once.
What happens next
Expect a short pause and a reopening auction, exactly as with LUDP.
Recent M halts
| Stock | Date | Halted for | Day move |
|---|---|---|---|
| NSRX | 2026-09-09 | 10 min | +0.00% |
| TAP | 2026-09-09 | 5 min | -0.08% |
| GCDT | 2026-09-08 | 5 min | +20.16% |
| OCNL | 2026-09-08 | 5 min | +0.00% |
| SMRX | 2026-09-08 | 5 min | +0.00% |
| QTOC | 2026-09-08 | 5 min | +0.00% |
| IONC | 2026-09-08 | 5 min | +0.00% |
| RGTC | 2026-09-08 | 5 min | +0.00% |
| RITA | 2026-09-08 | 6 min | +0.00% |
| WZRD | 2026-09-04 | 5 min | +0.00% |
| GTN | 2026-09-04 | 5 min | +0.02% |
| WLYB | 2026-09-04 | 5 min | +0.00% |
M halts: common questions
- What does halt code M mean?
- A single-stock volatility pause, the same mechanism as LUDP, carried under a different code by the reporting feed. On the halt feed it shows as "Volatility Trading Pause (LULD)".
- How long does a M halt last?
- Across 204 M halts where we captured a resume time, the median was 5 min, and nine out of ten resumed within 9 min. That is measured from our own halt feed, not an estimate. Individual halts vary and the exchange sets the actual resume time.
- What triggers halt code M?
- The same Limit Up-Limit Down bands. Despite the name it is not market-wide: the market-wide circuit breakers are M1, M2 and M3, and those halt every stock at once.
- What happens when the M halt lifts?
- Expect a short pause and a reopening auction, exactly as with LUDP.
- Can I trade a stock while it is halted?
- No. A halt stops trading on every US exchange at once, so no orders execute until the stock reopens. Orders can still be placed and cancelled, and the reopening auction can print well away from the last traded price.