Most traders attack a prop firm challenge asking "what's the most profitable EA I can run?" That's backwards. A challenge is a survival game with a profit target attached — the EAs that pass are the ones engineered around the rules, not the ones with the prettiest backtest.
The math that decides everything
A typical evaluation asks for 8–10% profit without ever losing 5% in a day or 10% overall. That asymmetry dictates your sizing, and it's tighter than it looks: with several correlated positions open, a 1%-per-trade EA can hit a daily cap in one session. Work the numbers with our risk-per-trade guide — for challenges, well under 1% per trade is common among passers.
The playbook
- Pick a firm that genuinely allows EAs. Rules differ more than marketing suggests — our 2026 comparison covers who allows what.
- Avoid mass-sold robots. Firms restrict strategies mirrored across many accounts; a marketplace bestseller is exactly that. See the FTMO EA rules breakdown.
- Wire the limits into the EA. Hard daily-loss and total-drawdown circuit breakers inside the robot — not a promise to watch the dashboard. Architecture in our prop-firm-safe EA guide.
- Validate like the money is real. Walk-forward and out-of-sample testing, sized against the worst historical day. A strategy that only worked in-sample will donate your challenge fee — here's why.
- Expect to take longer than the minimum days. The passers grind small edges under the caps; the blowups chase the target in week one.
Where Nebula fits
Nebula was built around this exact problem: drop in a prop-firm preset (or your firm's numbers), and every strategy it breeds is optimised under those caps, validated walk-forward, and exported as an MT4/MT5 EA with the circuit breakers compiled in. You get a strategy no one else is running, obeying the rules you're judged on.
No EA guarantees a pass — anyone claiming otherwise is selling something. Challenge fees are real money at risk. Nothing here is financial advice.