When to Sell Winning Stocks? I Backtested My "Half-Profit Take" Rule Against 15 Exit Strategies – My Current Rule Dominated!

Hey there, it's OJ. I build and run AI trading bots as a side gig.

Today, I'm not talking about bots, but the core investment strategy behind them. Specifically, the age-old question every growth investor faces: "When should you sell a winning stock?"

My current rule is super simple: "Once a stock doubles (+100%), I take half the profit to recoup my initial investment. The remaining half I hold indefinitely, until I judge the company's business model to be structurally broken."

I've followed this rule for years, feeling it was intuitively sound. But a nagging doubt recently crept in: "Is this truly optimal?" Maybe there's a smarter way to sell. Like a trailing stop-loss that sells if the price drops X% from its peak, or selling when it breaks below a moving average.

As an engineer, when a question arises, I want to validate it with data. So, I rigorously backtested my current rule against 15 alternative exit strategies. Here's the full breakdown.