Mechanism
Markets are not interchangeable. The “same stop” behaves differently depending on:
- trading hours (gaps vs continuous),
- liquidity depth (slippage),
- venue rules (halts, limit moves),
- and payoff structure (linear vs convex).
When traders blow up in new products, it’s usually not because the idea was wrong. It’s because they applied the wrong physics: wrong sizing assumptions, wrong gap assumptions, wrong execution assumptions.
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.
How it kills accounts
Port a strategy to a new instrument → assume similar fills and volatility → ignore contract rules → surprise move/halts/gaps → losses exceed plan → forced liquidation.
How it kills accounts:
- The rule exists only in your head.
- Stress arrives and you improvise.
- Improvisation becomes inconsistency.
- Inconsistency becomes random results.
- Random results become a slow bleed.
Rule that survives
Before trading a new instrument, write the “physics sheet”: hours, typical spread/slippage, margin rules, and worst-case gap behavior.
Reduce size until you have live evidence of execution quality.
If the payoff is convex (options), rethink stops and risk entirely.
Rule that survives:
- Write the trigger in observable terms.
- Write the action in one sentence.
- Write the penalty for breaking it.
Example archetype
A trader moves from FX to small-cap stocks and expects continuous liquidity. A halt occurs, then a gap reopens the next print far away. The stop didn’t ‘fail’; the instrument behaved as designed.
Tell: if your rule isn’t enforceable, it’s a suggestion. Suggestions don’t survive stress.
Deep dive
Physics sheet
Write what can happen when you are not allowed to trade.
Related: Stop-losses fail in volatility spikes and Most blowups are operational.
Glossary: gap risk, slippage, payoff distribution.
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.