Quantitative impact of correlation errors on basket options with time‐varying correlations

This study examines the quantitative impact of correlation errors on basket options with time‐varying correlations and the risk measures (conditional) value‐at‐risk (VaR) in the framework of Basel II. The results show that risk measure misestimation due to correlation errors are the largest and most asymmetric for the at‐the‐money and out‐of‐the‐money basket option. Delta hedging of the basket option reduces risk but increases size and asymmetry effects substantially. Finally, the square‐root‐of‐time rule for VaR does not adjust adequately to correlation errors and consistently underestimates risk measures, which could lead to the VaR exceedance clustering observed during the recent financial crisis. © 2011 Wiley Periodicals, Inc. Jrl Fut Mark