S&P- BRK Divergence

Playing with the charts, the recent divergence between the price of BRK and the S&P is quite remarkable, 20% in just a few months. I can’t find much in the way similar divergence outside of early rapid growth spurts and the dot com crash. I wonder if we will see a return to trend, and if it would be us going down or the index coming up. I looking at valuations, some of the shift will probably stick.