I would define "the market" as the maximally diversified portfolio fitting a given risk profile. If you're limited to large cap US stocks, then yeah, the S&P 5

I would define "the market" as the maximally diversified portfolio fitting a given risk profile. If you're limited to large cap US stocks, then yeah, the S&P 500 would be the market. Better to think of a globally diversified portfolio though. By 'beat the market', I mean have a consistent expectation of outperforming the market by a sufficient amount to justify the effort and risk. Obviously there is a ton of uncertainty, so simply achieving higher returns than a given benchmark is not, for these purposes, beating the market. Unfortunately, that also means it's impossible to ever be 100% sure you have indeed determined a way to beat the market, although obviously the more logical the reasoning behind your approach, and the more evidence of it being successful, the more confident you would be. So, is this impossible? No. As he even says in the article, the expected equilibrium would be that it's possible to the extent that the professionals engaged in doing it earn just more than they would at their next best alternative. But is it possible to consistently do even better than that, or at significantly less effort? Unlikely. If it were, you would have found the metaphorical 20 dollar bill in the middle of Grand Central Station.