Perold (2007) shows that, given a diffuse prior that is being updated in light of a noisy market price, the posterior distribution says that value-weighting and equal-weighting one's portfolio makes no difference. We argue that the diffuse prior is hard to reconcile with reality and that a...

In this article, the authors find that a typical application of volatility-timing strategies to the stock market suffers from a look-ahead bias, despite existing evidence on successes of the strategies at the stock level. After correcting the bias, the strategy becomes very difficult to...