Basically, they calculate the "volatility smirk" (the difference between the implied volatility for At-The-Money (ATM) calls and Out-of-The-Money (OTM) puts) for individual stocks. They then sort firms into portfolios based on deciles of the smirk, and compare returns for the various portfolios (or for "hedge portfolios" constructed by shorting the "high smirk" decile and going long the "low smirk" decile) . The logic for this approach is the hypothesis that informed traders with negative news will choose to buy OTM puts, thereby causing a divergence in the IV of the puts vs for the call.
The shape of the volatility smirks has significant cross-sectional predictive power for future equity returns. Stocks exhibiting the steepest smirks in their traded options underperform stocks with the least pronounced volatility smirks in their options by around 15% per year on a risk-adjusted basis. This predictability persists for at least six months, and firms with steepest volatility smirks are those experiencing the worst earnings shocks in the following quarter. The results are consistent with the notion that informed traders with negative news prefer to buy out-of-the-money put options, and that the equity market is slow in incorporating the information embedded in volatility smirks.
All in all, a pretty cool paper showing how information flows across markets. Given some work I'm doing with options data, I found it to be particularly timely.
Read the whole thing here.
HT: CXO Advisory Group