Routinely, practitioners and academics alike propose the use of trading strategies with an
alleged improvement on the risk–return relation, typically entailing a considerably higher
return for the given level of risk. A very popular example is” A quantitative approach to
tactical asset allocation” by the fund manager M. Faber, a real hit in the SSRN online library.
Is this paper a counterexample to market efficiency? We reject this conclusion, showing that
a lot of caution should be used in this field, and we indicate a series of bootstrapping
experiments which can be easily implemented to evaluate the performance of trading
strategies.