It’s a familiar story in the world of algorithmic trading. You spend weeks, maybe months, crafting a trading strategy. You run it through a backtest on historical data, and the results are breathtaking. The equity curve soars upwards, a beautiful, steady climb to financial freedom. You feel a surge of excitement—you’ve cracked the code. Then, you deploy it with real money. Within days, the strategy starts to bleed. The perfect curve inverts, and the trades that looked like genius moves in the backtest are now consistent losers. What went wrong? The painful truth is that your strategy was likely never profitable to begin with. Its stellar performance was an illusion created by common, subtle, and devastating backtesting mistakes. Before you risk another dollar, it’s crucial to understand these pitfalls. We'll explore the three most notorious "silent killers" of trading strategies: look-ahead bias, survivorship bias, and overfitting. This isn't about specific en...