Except ... he hasn't beaten the index for most of the last decade (well, it's been on and off, but the end points are close, and he spent years underperforming it), so ... uh ... did you click the link? Here's another - him against a vanilla value index at Vanguard and any divergence is essentially in the noise, higher or lower depending on which point you pick to end the run. This isn't surprising, either. Large actively-managed funds generally end up behaving like indexes at some point, because they are too big to do anything but hold large swathes of the market. Meanwhile, if you'd bought a small cap value index to take a little more risk and go with smaller companies you'd have beaten BRKB handily - I'd argue that with its lack of the manager risk layer and high number of holdings it's a better risk-adjusted bet than any single stock, including BRK.B, yet there it is, outperforming ...Warren was able to achieve amazing returns early on because he had less capital and was
more nimble- now he can't shift around as quickly, pick up small value plays discreetly, etc... Again, it's like Apple: the time to buy was before they became the most valuable tech company in America - now they have a lot less upside. He even says somewhere (can't remember where) he doesn't expect to beat the index going forward, or that people might as well index over buying BRK, or something to that effect.