There are many private portfolios that "beat the market." Of course, you can extend the timeline or find myriad other ways to exclude them. It's very hard to be a hedge fund and beat the market because they do not have the luxury of sitting out poor market conditions.
I'm not suggesting "anybody can do it" but the study that concludes money managers underperform the market often gets stretched into "nothing beats index funds".
I'm not suggesting "anybody can do it" but the study that concludes money managers underperform the market often gets stretched into "nothing beats index funds".