You can win 70% of your trades and still lose money

Winning seven out of ten trades sounds like the kind of result a trader should be pleased with. Yet an account can lose money over those same ten trades. Win rate measures how often a position closes in profit, but it says nothing about the size of each win or loss. When a few losing trades cost much more than the winning ones earn, a seemingly impressive success rate can conceal a strategy that is gradually losing money.