No abstract

Exchange-traded products (ETPs) linked to futures contracts on the CBOE S&P 500 Volatility Index (VIX) have grown in volume and assets under management in recent years, in part because of their perceived potential to hedge against stock market losses.In this paper we study whether VIX-related ETPs can effectively hedge a portfolio of stocks. We find that while the VIX increases when large stock market losses occur, ETPs which track short term VIX futures indices are not effective hedges for stock portfolios because of the negative roll yield accumulated by such futures-based ETPs. ETPs which track medium term VIX futures indices suffer less from negative roll yield and thus appear somewhat better hedges for stock portfolios. Our findings cast doubt on the potential diversification benefit from holding ETPs linked to VIX futures contracts.We also study the effectiveness of VIX ETPs in hedging Leveraged ETFs (LETFs) in which rebalancing effects lead to significant losses for buy-and-hold investors during periods of high volatility. We find that VIX futures ETPs are usually not effective hedges for LETFs.

No abstract

Exchange-traded products (ETPs) linked to futures contracts on the CBOE S&P 500 Volatility Index (VIX) have grown in volume and assets under management in recent years, in part because of their perceived potential to hedge against stock market losses.In this paper we study whether VIX-related ETPs can effectively hedge a portfolio of stocks. We find that while the VIX increases when large stock market losses occur, ETPs which track short term VIX futures indices are not effective hedges for stock portfolios because of the negative roll yield accumulated by such futures-based ETPs. ETPs which track medium term VIX futures indices suffer less from negative roll yield and thus appear somewhat better hedges for stock portfolios. Our findings cast doubt on the potential diversification benefit from holding ETPs linked to VIX futures contracts.We also study the effectiveness of VIX ETPs in hedging Leveraged ETFs (LETFs) in which rebalancing effects lead to significant losses for buy-and-hold investors during periods of high volatility. We find that VIX futures ETPs are usually not effective hedges for LETFs.

We propose a robust portfolio optimization approach based on Value-at-Risk (VaR) adjusted Sharpe ratios. Traditional Sharpe ratio estimates using a limited series of historical returns are subject to estimation errors. Portfolio optimization based on traditional Sharpe ratios ignores this uncertainty and, as a result, is not robust. In this paper, we propose a robust portfolio optimization model that selects the portfolio with the largest worse-case-scenario Sharpe ratio within a given confidence interval. We show that this framework is equivalent to maximizing the Sharpe ratio reduced by a quantity proportional to the standard deviation in the Sharpe ratio estimator. We highlight the relationship between the VaR-adjusted Sharpe ratios and other modified Sharpe ratios proposed in the literature. In addition, we present both numerical and empirical results comparing optimal portfolios generated by the approach advocated here with those generated by both the traditional and the alternative optimization approaches.