Martingale and grid Expert Advisors: how they work and what can go wrong

How a grid works

A grid EA places orders at fixed price steps above and below the market and closes them in profit as price swings back and forth. It tends to do well in ranging markets and can collect many small wins.

How martingale works

Martingale increases the position size after a losing trade so that one winner recovers earlier losses. The idea is simple, but the position size grows quickly with each added step.

Where the risk is

The risk is a strong trend that does not reverse. Open positions pile up in loss, margin is used up, and a single event can wipe out many small wins. A smooth equity curve in a backtest can hide this tail risk.

What to check before using one

Treat these as minimum checks.

• A maximum number of grid levels or martingale steps.
• A hard stop loss or equity stop that closes everything.
• A lot size that survives the worst-case step on your balance.
• A hedging account if the EA opens positions in both directions.

Size it for the worst case

Use a small lot size and calculate what the full ladder of positions would cost at the end of the grid. If you cannot accept that loss, reduce the size or choose a different type of strategy.