We revisit the apparent historical success of technical trading rules on daily prices of the DJIA from 1897 to 2011. We use the False Discovery Rate as a new approach to data snooping. The advantage of the FDR over existing methods is that it selects more outperforming rules and diversifies against model uncertainty. Persistence tests show that an investor would never have been able to select ex ante the future best-performing rules. Moreover, even the in-sample performance is completely offset by the introduction of transaction costs. Overall, our results seriously call into question the economic value of technical trading rules.

Keywords : Technical Trading, False Discovery Rate, Persistence, Transaction Costs.

JEL : C12, C15, G11, G14.