M1Halt — Corporate Action
M1 marks a corporate action halt. Something is changing about the security itself — a reverse split, a name or symbol change, a merger, a spin-off, a reorganization — and trading pauses so the change can be applied cleanly. It is administrative rather than informational.
What triggers it
- A pending or effective corporate action requiring the security's terms, symbol, or share count to change.
- Reorganizations where the outstanding security is being exchanged for another.
How long it lasts
Usually brief and scheduled, because the corporate action is known in advance.
How it resumes
Trading resumes under the updated terms, which may include a new symbol, adjusted share count, and adjusted price.
What it means for a day trader
Charts break across M1 events. Unadjusted price history through a reverse split will corrupt any backtest that spans it.
Reverse splits on small caps are frequently a compliance response to a minimum bid price deficiency — the M1 is the mechanic, the H4 risk is the context.
Related halt codes
Track M1 halts as they happen
Halt Strategy monitors live NASDAQ and NYSE halts, replays the setup around each event, and backtests outcomes segmented by halt code — so M1 events are never averaged in with everything else.
Primary sources
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.