Position Sizing
Also known as: sizing, trade size, risk per trade, bet sizing
Position sizing is the decision of how much capital to commit per trade, conventionally expressed as a percent of account equity risked between entry and stop, and is the single biggest lever a trader has over long-term outcomes.
Most traders spend their time picking entries. The math says they should spend it picking sizes. Two traders with identical setups and identical win rates can produce wildly different equity curves based purely on how they size, and the sizing decision is the one the trader fully controls.
The most defensible default is fixed-fractional sizing: risk a small constant percentage of equity per trade, commonly between half a percent and two percent. This naturally compounds wins and damps losses, never bets the account, and removes the temptation to size by feel. More sophisticated approaches (Kelly fractions, volatility-adjusted sizing) all build on the same principle: size is a function of measured edge and measured risk, not conviction.
The fingerprint of bad sizing is variance in position size that has nothing to do with setup quality, bigger on revenge re-entries, smaller after a winning streak. Gecko flags that variance directly.
Per-trade dollar risk (entry minus stop times size) divided by account equity; consistency of that fraction across trades.
Surfaces inside Size Discipline on the diagnosis.
Paul Tudor Jones doesn't talk about prediction, he talks about defense — a 5-to-1 reward-to-risk minimum, never averaging losers, and cutting size in a drawdown. Here's how each shows up as a number in your own trade history.
Upload a broker statement and Gecko names this pattern in your data, in dollars, alongside 11 other behavioral axes. First 100 trades free.
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