What is the 84% rule in trading?

No universal "84% rule" exists in trading; it may refer to specific strategies or stats like 84% win rates claimed by vendors (often misleading). Common rules are 90% loss rate or 2% risk per trade. High win-rate systems sacrifice reward:risk, needing precision. Verify any "rule" against backtests and live results. Focus on expectancy—(win% × avg win) - (loss% × avg loss) > 0.