Abstract
Characteristic-based factors embed large unpriced common components that depress Sharpe ratios and lead to deviations from the mean-variance efficient (MVE) frontier. We discuss how to decompose tradable factor returns into priced (MVE) and unpriced components, showing that hedging unpriced variation realigns factors with efficiency. We outline theoretical conditions for characteristic portfolios to span the MVE portfolio and describe practical hedge portfolio construction. In some asset classes—currencies and sovereign bonds—real-time estimation of the MVE portfolio is feasible. In the case of equities, one can hedge unpriced risks from characteristic-based factors. Empirically, unpriced risks account for 30–99% of factor return variance, and hedging can more than double Sharpe ratios.