A profitable-looking entry rule does not guarantee a growing account. Position sizing determines how much capital is exposed to a trade, while market direction and execution remain uncertain. Fixed fractional sizing sets a chosen risk budget as a fraction of account equity; it does not predict prices or make a trading system profitable.
What fixed fractional sizing means
First define the trading capital being used for the calculation. A fixed fraction is then applied to the account equity to estimate a maximum planned loss for one trade. The fraction is a personal risk choice, not a recommended percentage. A position must also account for the distance between entry and the planned exit, contract value, fees and currency conversion where relevant.
Formula and worked example
Planned risk budget = account equity × chosen risk fraction
Estimated position size = planned risk budget ÷ estimated loss per unit at the exit level
For illustration only, suppose the trading account is ฿10,000 and a trader chooses 1% as a hypothetical risk fraction. The planned risk budget would be ฿100. If the estimated loss from entry to the planned stop is ฿5 per unit, the calculation gives 20 units (฿100 ÷ ฿5). This is only an arithmetic example, not a suitable risk level or trade recommendation.
Actual losses can differ because of gaps, slippage, fees, liquidity, leverage, contract multipliers or an exit that does not execute at the expected price. A stop order does not guarantee a particular fill price.
How anti-Martingale differs from Martingale
The source uses the term “Antingale.” The more common term is anti-Martingale, sometimes called reverse Martingale: a system increases exposure after wins and reduces it after losses, according to its own rules. Martingale approaches generally increase exposure after losses in an attempt to recover them. Variants differ, and neither label removes market risk. Increasing size after wins can still lead to substantial losses when conditions change.
What money management can and cannot do
A position-sizing rule can make exposure more consistent and help a trader follow a plan. It cannot guarantee profits, eliminate drawdowns, remove emotional decisions or make a strategy suitable for every market. Test the complete rules with realistic costs and adverse scenarios, and avoid using money needed for living expenses, emergency savings or long-term obligations.
The CFTC warns that futures trading is volatile and risky, with possible losses beyond the initial amount invested. FINRA also warns that frequent trading on margin can lead to losing some or all of the investment and potentially more than the amount initially deposited. Read the CFTC futures risk guidance and FINRA’s guide to frequent intraday trading. This article is educational, not individual financial advice.
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