Modeling asymmetric comovements of asset returns

Existing time-varying covariance models usually impose strongrestrictions on how past shocks affect the forecasted covariancematrix. In this article we compare the restrictions imposedby the four most popular multivariate GARCH models, and introducea set of robust conditional moment tests to detect misspecification.We demonstrate that the choice of a multivariate volatilitymodel can lead to substantially different conclusions in anyapplication that involves forecasting dynamic covariance matrices(like estimating the optimal hedge ratio or deriving the riskminimizing portfolio). We therefore introduce a general modelwhich nests these four models and their natural 'asymmetric'extensions. The new model is applied to study the dynamic relationbetween large and small firm returns.     

Inferring future volatility from the information in implied volatility in Eurodollar options: a new approach

We study the information content of implied volatility fromseveral volatility specifications of the Heath-Jarrow-Morton(1992) (HJM) models relative to popular historical volatilitymodels in the Eurodollar options market. The implied volatilityfrom the HJM models explains much of the variation of realizedinterest rate volatility over both daily and monthly horizons.The implied volatility dominates the GARCH terms, the Glostenet al. (1993) type asymmetric volatility terms, and the interestrate level. However, it cannot explain that the impact of interestrate shocks on the volatility is lower when interest rates arelow than when they are high.