Risk management in MQL5: position sizing and stops that survive a losing streak
A few years back I had an EA with a 68% win rate in the tester. It looked fantastic. I dropped it on a small live account at a flat 0.20 lots per trade, left it running, and came back a week later to a 41% drawdown. The signals had behaved - roughly what the backtest promised. What drained the account was that I'd hard-coded the lot size and paid no attention to how far the stop sat from entry. A few wide-stop losers in a row, every one of them sized exactly like the tight-stop winners, and the arithmetic…