Several influential studies show that transformations of implied volatilities calculated from options prices predict stock returns. This predictability is puzzling because market participants readily observe options prices. We find that this predictability is consistent with implied volatilities reflecting stock borrow fees that are known to predict stock returns. We derive a formula relating the option-implied volatility spread to the borrow fee. Motivated by this relation, we show that the return predictability from implied volatility spread and skew decreases by at least two-thirds if high-fee stocks are excluded. The patterns for other predictors computed from option implied volatilities are similar.

ABSTRACT Short‐sale costs eliminate the abnormal returns on asset pricing anomaly portfolios. While many anomalies persist out‐of‐sample before accounting for short‐sale costs, they cannot be exploited with long‐short strategies due to stock borrow fees. Using a comprehensive sample of 162 anomalies, the average long‐short portfolio return is a significant 0.14% per month before short‐sale costs, and the returns are due to the short leg. However, the average is −0.01% once returns are adjusted for borrow fees. Moreover, anomalies are not profitable even before fees if the high‐fee observations, representing 12% of stock dates, are excluded from the analysis.