> it is trivially easy to beat this strategy by choosing an index that performs better historically. Past performance is no guarantee... This is a very subtle

> it is trivially easy to beat this strategy by choosing an index that performs better historically. Past performance is no guarantee... This is a very subtle question which is far from resolved[1] in the academic literature; it is nowhere close to the slam-dunk you state it is. [1]: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3122326 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3122326