How to set up an Expert Advisor for a prop firm challenge: risk, drawdown and testing

Step 1: write down the firm's limits

Before touching the EA, list the numbers that end a challenge: maximum daily loss, maximum total drawdown, profit target, minimum trading days, time limit, and how drawdown is measured, for example on balance or equity and from the start-of-day balance or the highest balance. Note any restrictions on news, weekend holding and trade duration.

Step 2: confirm the EA is allowed

Check the firm's EA policy for the account type and platform you intend to use, and ask in writing whether your specific EA is acceptable. Some firms require source-code ownership or pre-approval for third-party tools. Do this before paying the fee.

Step 3: convert the limits into risk per trade

Decide how much of the daily limit one trade, and one bad day, may use. A common way to think about it is to keep the loss from a full losing sequence comfortably inside the daily limit, not just a single trade. Then convert that into a lot size or risk percentage using the stop distance of the EA.

If the EA opens several positions at once, size for the combined worst case, not for each position alone.

Step 4: add protection inside the firm's limits

Set the EA's own daily-loss or equity stop well inside the firm's limit so the EA stops before the firm does. If the EA has no such setting, you must reduce size and monitor the account yourself. Also check for a maximum number of open trades, a spread filter and a news filter.

Step 5: match the symbols, hours and platform

Confirm the firm's symbol names, trading hours and contract specifications, and attach the EA only to symbols it was built for. Check the platform requirement, whether a VPS is allowed, and whether any external DLL or web request used by the EA is permitted.

Step 6: rehearse on a demo account

Run the EA on a demo account with the same balance, risk and filters for several weeks. Record the maximum drawdown, the worst day and any trades that breach the firm's restrictions. Compare it with your backtest and adjust the size before you commit a challenge fee.

Step 7: monitor and respect the rules during the challenge

Check the account daily, pause the EA around major news if the firm restricts it, and do not change settings impulsively after a loss. Keep records of the EA's behaviour in case the firm asks you to explain a trade.

There is no setting that guarantees a pass. The aim is to survive the limits and let a sound strategy have enough time to work.