Margin Is Not Risk, Notional Is Risk

Margin is the deposit required to hold a leveraged position. It is not a cap on losses.

Your P&L changes with the instrument’s price movement multiplied by your notional. If your notional is large relative to equity, normal volatility becomes account-level damage.

This is why accounts with “low margin used” can still be fragile: a small market move can consume equity faster than you can react, and margin requirements can increase at the same time.

Practical framing: the market is a feedback system. Your job is to remove the behaviors that produce the same loss pattern, not to “feel better” about it.

• Turn recurring mistakes into hard gates.
• Reduce degrees of freedom when you’re losing.
• Make the next decision simpler than the last.

Low margin used → feel safe → increase notional → normal move hits → equity drops faster than expected → free margin collapses → margin call / liquidation → bad fills lock in loss.

How it kills accounts:

1. The rule exists only in your head.
2. Stress arrives and you improvise.
3. Improvisation becomes inconsistency.
4. Inconsistency becomes random results.
5. Random results become a slow bleed.

Size from notional and worst-case move, not from margin required.
Keep a margin buffer that assumes spreads widen and stops slip.
If a 2–3× normal move would threaten liquidation, you are oversized.

Rule that survives:

• Write the trigger in observable terms.
• Write the action in one sentence.
• Write the penalty for breaking it.

You post a small margin deposit and control a large position. Price moves a little, equity drops a lot. The broker increases margin during volatility and you’re closed out even though your ‘margin used’ looked fine.

Tell: if your rule isn’t enforceable, it’s a suggestion. Suggestions don’t survive stress.

How to think about it

Margin is the ticket price. Notional is the ride.

Related: Forced liquidation is the only thesis and Sequence risk beats your average.

Glossary: margin, leverage, margin call, liquidation.

Broker reality: Margin requirements may change without notice.

Field checklist

• Write the rule in observable terms: if X, then Y.
• Remove choices under stress. Choices become rationalizations.
• Track the precursor: what state were you in before the mistake?
• Make deviations costly (size down, pause, review).
• Turn lessons into gates, not notes.