Some people think backtesting is supposed to predict the future. The best it can do is show you the past. For those that say backtesting doesn't take into account news, etc., of course it does. It takes into account everything. It's the resulting price when everything that happened is taken into account. But if you expect backtesting or forward testing or anything else to accurately predict the future, good luck. Even the AI programs that use neural networks to attempt to model it aren't perfect, although I've heard some win more than lost, and that's all that matters, right? After that, it's just how much money you're willing to risk.