Most backtests you see on here are lying to you. Not always on purpose. But a lot are lying. Here's the biggest trick nobody talks about. They test with what they know NOW, not what they knew BACK THEN. Someone backtests "buy the top 10 Nasdaq stocks since 2015" and it looks incredible. But they used TODAY's top 10. $NVDA, $META, all the winners. In 2015 you had no idea those would be the winners. The stocks that blew up and got kicked out of the index? Gone from the test like they never existed. That's not a strategy. That's hindsight with a chart. The other ways they fool you Perfect fills. They assume every trade fills at the exact price on the screen. In real life you miss fills, get re-quoted, and pay the spread. On options that alone can turn a winner into a loser. No fees. Commissions, exchange fees, settlement fees, data costs. Leave all that out and a losing strategy suddenly looks great. Cherry picked start dates. Start the test right at the bottom of a crash and anything looks genius. Curve fitting. Tweak the settings 500 times until the past looks perfect. Then it falls apart the second it trades live. Only testing bull markets. Everything works when the market only goes up. A few lucky trades. Take out the 5 best trades and see what's left. A lot of "amazing" strategies are just one or two monster wins carrying everything. So before you trust any backtest, ask these 6 questions. 1. Did you use the stock list from back then, or today's? 2. Are the fills from real quotes at that minute, or the perfect price? 3. Are every fee and cost included? 4. What happens if you start on a different day? Or the worst day? 5. Does it still work after removing the best 5 trades? 6. Did it survive a real bear market, not just 2023 and 2024? If they can't answer those, it's not a backtest. It's marketing. That's the standard I hold my own bots to. Every one of those questions, every start date since 2018, real quotes on every trade, plus stress tests for 2000 and 2008. It's a lot of work, and it's the only way I'd ever put money behind something. Next time someone shows you a backtest, ask them one question. Did you use what you knew back then, or what you know now? Most of them won't have an answer. $SPY $SPX $ES $QQQ $NDX $NQ $VIX