Position Sizing from Stop-Loss Distance and Capital at Risk

Summary

The article explains money management as control over the loss a trade can incur, rather than as a formula that scales lots only with account balance. It argues that strategy performance depends on win rate, average win, and average loss, and that losses must be limited because high win rates can conceal rare, account-damaging drawdowns. The author favors a hard stop-loss and treats the stop distance and per-pip value as inputs to position sizing.

The proposed procedure is to choose a stop based on market conditions, set the capital amount at risk, and calculate trade volume so the loss at the stop matches that budget. An example converts a euro risk budget and an 80-pip stop into a lot size using the exchange rate and pip value. The article cautions against fixed stop distances that ignore price action and against relying on an assumed universal risk percentage. Its formula and example depend on pip-value conventions and account details, so the calculation must be adapted to the instrument and trading setup.

Key ideas

• Strategy expectancy depends on win rate, average win, and average loss together.
• A high win rate can hide infrequent losses large enough to severely damage an account.
• The author recommends setting a market-informed stop-loss before calculating trade volume.
• Position size should translate the chosen risk budget and stop distance into a per-pip value.
• The article questions fixed risk-percentage rules and fixed stop distances that ignore market conditions.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.