Why it matters
Margin determines whether you can stay in the trade during volatility.
Decision use: treat this term as a risk input. If you can’t observe it, you can’t size for it.
Common trap
Running margin near the limit, assuming conditions stay normal.
Example
Broker raises margin requirements; you’re forced out.
Operational cue: if you can’t point to it on the chart, in the DOM, or in your broker logs, treat it as a story and trade smaller.
Notes
Margin is survival infrastructure, not a detail.
Quick rule
- If you see this repeatedly, you are in a different regime than your model assumes.
- Regime change usually means position size change.
- When in doubt: trade smaller, or don’t trade.