Is Aggregate Idiosyncratic Risk Priced? Follow the Bid-Ask Bounce

This paper models a market microstructure bias, driven by the bid-ask spread, that is evident in the pricing of aggregate firm-level risk embodied by the stock return variance estimates of Goyal and Santa-Clara (2003). Controlling for this bias, we find no pricing ability for aggregate firm-level variance for the period 1927 to 2012 or for any sub-period tested. Market microstructure also explains the time-trend of aggregate firm-level volatility observed from 1962 to 1997 (Campbell, Lettau, Malkiel, and Xu, 2001), and subsumes any relation between retail trading and future idiosyncratic volatility from 1983 to 1999 (Brandt, Brav, Graham, and Kumar, 2010). We conclude that the aggregate firm-level bid-ask spread is priced with future market returns rather than any of the aggregate firm-level risk measures