3 Cheers For Sloth and Simplicity in 403(b) Forum Posted 9 hours ago · Report reply It is a verifiable fact that in the past people have seen better results with portfolios that disproportionately invest in small caps. Although as Bogle pointed out in one of his books, literally every investment scheme people preach is guaranteed to work well with prior data. If these schemes didn't backtest well, it would be quite difficult to sell something that's been a historic failure. The argument Bogle goes on to make (and I agree) is that the overperformance in particular asset classes or investment approaches is likely due to one of two things: Pure random chance and we're seeing a pattern where one doesn't exist (something that humans are notorious for, think of how many shapes you can see in clouds for example). A strategy that wasn't lucky, but worked in the past due to conditions that are no longer present or explainable.