I think you have misunderstood Buffett theory. Most (i.e., more than 50%) of actively managed funds underperform, but in aggregate the amount of underperformanc

I think you have misunderstood Buffett theory. Most (i.e., more than 50%) of actively managed funds underperform, but in aggregate the amount of underperformance across all funds is roughly equivalent to the management fees they charge. Imagine a bell curve centered around the overall market's returns, but shifted over by a few percent to account for the fees. An inverse of all major actively managed funds will get you the same average performance before the fees (the same as the overall market's), but it won't dip into those managers' bank accounts and transfer their fees to you. It will charge its own fees. So it will underperform, too. The management fee for this ETF, for example, is 1.2% per year.