Hi Norbert, thanks for your comments. We applied the academic definition of alpha representing unexplained returns, but can actually explain most of BRK's outperformance by exposure to factors like Value or Low Volatility. These have been known for decades, although Warren Buffett was one of the early adopters.

Our perspective is that Warren Buffett is highly skilled in portfolio construction and harvesting factor returns, which might be called craftsmanship alpha. We're not critical of his success, just provide a different perspective.

I think the article on Winton makes a case for factor investing as they are moving away from trend following towards risk premia strategies.