Position Sizing for Automated Systems

Most accounts are not lost because of bad entries — they are lost because of bad sizing. How much you put on each trade decides whether a normal losing streak is a small dip or the end of the account. For an automated system that trades while you sleep, getting this right is everything.

Size relative to the account

A lot size that is fine on one account can be reckless on a smaller one. Sizing should scale with the account, not be a fixed number copied from someone else. The right question is not 'how many lots' but 'how much of the account is at risk'.

Exposure and drawdown limits

• Cap how much total exposure the system can hold at once.
• Set a maximum number of open positions or grid steps.
• Define a drawdown level where the system stops adding risk.

Consistency matters

Wildly varying position sizes make results impossible to judge and can breach the rules of many prop firms. Consistent, rule-based sizing keeps both your risk and your statistics honest.

The bottom line

Entries get the attention, but sizing keeps you in the game. Decide your risk per trade and your hard limits first, and let the automation respect them without exception. Trading carries real risk — sound sizing is how you survive long enough for an edge to matter.