Interest Rate Exposure of Volatility Portfolios

Abstract

The authors assess the exposure of stock portfolios sorted by total volatility to interest rate risk and determine whether this nonequity risk can explain differences in risk and risk-adjusted returns between low- and high-volatility portfolios over a 25-year period for U.S. equities. They find that the addition of an interest rate risk factor to the four-factor model reveals a small but positive duration for low-volatility portfolios. However, this new factor fails to improve the explanatory power of the model for both low- and high-volatility portfolios and has no significant impact on the portfolios’ risk-adjusted return. The authors find that interest rate factor loadings are fairly robust across different specifications of the multifactor model for low-volatility portfolios but are unstable for high-volatility portfolios. For all volatility portfolios under study, the significance of the results is highly dependent on the choice of time period.