This paper examines data from 45 world markets and shows that the previously documented relation between mean returns and idiosyncratic volatility arises because of biases in volatility estimates that we can attribute to the bid-ask bounce in trade prices. We show that no significant relation...

We examine the cross-sectional relation between idiosyncratic volatility and stock returns and propose that the joint effect of the percentage of zero returns, that affects the loading on the systematic risk factors, and the bid-ask spread, that inflates the variance of the returns, biases the...