Barbara Ostdiek

The Economic Value of Volatility Timing Using 'Realized' Volatility

Recent work suggests that intradaily returns can be used to construct estimates of daily return volatility that are more precise than those constructed using daily returns. We measure the economic value of this “realized” volatility approach in the context of investment decisions. Our results indicate that the value of switching from daily to intradaily returns to estimate the conditional covariance matix can be substantial. We estimate that a risk-averse investor would be willing to pay 50 to 200 basis points per year to capture the observed gains in portfolio performance. Moreover, these gains are robust to transaction costs, estimation risk regarding expected returns, and the performance measurement horizon. JEL classification: G11, G14

Trading Costs and the Relative Rates of Price Discovery in Stock, Futures, and Option Markets

In frictionless and rational markets, perfect substitutes must have the same price. In markets with trading costs, however, price differences may be as large as the costs of executing the arbitrage between markets. Moreover, if trading costs differ, trading activity will tend to be concentrated in the lowest-cost market. This study tests the differential trading cost hypothesis by examining the rate at which new information is incorporated in stock, index futures, and index option prices. The lead/lag return relations among markets are consistent with their relative trading costs. Prices in the index derivative markets appear to lead prices in the stock market. At the same time, index futures prices tend to lead index option prices, and the prices of index calls and index puts move together. The trading cost hypothesis reconciles the disparity found between the temporal relation in the stock index/index derivative markets versus the stock/stock option markets.

The impact of energy derivatives on the crude oil market

We examine the effects of energy derivatives trading on the crude oil market. There is a common public and regulatory perception that derivative securities increase volatility and can have a destabilizing effect on the underlying market. Consistent with this view, we find an abnormal increase in volatility for three consecutive weeks following the introduction of NYMEX crude oil futures. While there is also evidence of a longer-term volatility increase, this is likely due to exogenous factors, such as the continuing deregulation of the energy markets. Subsequent introductions of crude oil options and derivatives on other energy commodities have no effect on crude oil volatility. We also examine the effects of derivatives trading on the depth and liquidity of the crude oil market. This analysis reveals a strong inverse relation between the open interest in crude oil futures and spot market volatility. Specifically, when open interest is greater, the volatility shock associated with a given unexpected increase in volume is much smaller.

Stochastic Volatility, Trading Volume, and the Daily Flow of Information

We use state-space methods to investigate the relation between volume, volatility, and ARCH effects within a mixture of distributions hypothesis (MDH) framework. Most recent studies of the MDH fit AR(1) specifications that require the information flow to be highly persistent. Using a more general specification, we find evidence of a large nonpersistent component of volatility that is closely related to the contemporaneous nonpersistent component of volume. However, in contrast to studies that fit volume-augmented GARCH models, we find no evidence that volume subsumes ARCH effects. Since volume-augmented GARCH models are subject to simultaneity bias, our findings should be more robust than these prior results.

The world ex ante risk premium: an empirical investigation

Abstract A number of recent papers have focused on testing the linearity restrictions implied by international asset pricing models. The tests, however, have not addressed an additional restriction implied by the models; namely, that the risk premium on the world portfolio is positive. This study provides a direct assessment of this restriction. The evidence indicates that the ex ante world market risk premium can be negative. The results are robust to market proxies that are hedged and unhedged with respect to currency risk. Subperiod analysis indicates that the rejection of the positive risk premium restriction is driven by the first half of the sample period.

Optimizing the Performance of Sample Mean-Variance Efficient Portfolios

We propose a comprehensive empirical strategy for optimizing the out-of-sample performance of sample mean-variance efficient portfolios. After constructing a sample objective function that accounts for the impact of estimation risk, specification errors, and transaction costs on portfolio performance, we maximize the function with respect to a set of tuning parameters to obtain plug-in estimates of the optimal portfolio weights. The methodology offers considerable flexibility in specifying objectives, constraints, and modeling techniques. Moreover, the resulting portfolios have well-behaved weights, reasonable turnover, and substantially higher Sharpe ratios and certainty-equivalent returns than benchmarks such as the 1/N portfolio and S&P 500 index.

ARCH Effects and Trading Volume

Studies that fit volume-augmented GARCH models often find support for the hypothesis that trading volume explains ARCH effects in daily stock returns. We show that this finding is due to an unrecognized constraint imposed by the GARCH specification used for the analysis. Using a more flexible specification, we find no evidence that inserting volume into the conditional variance function of the model reduces the importance of lagged squared returns in capturing volatility dynamics. Volume is strongly correlated with contemporaneous return volatility, but the correlation is driven largely by transitory volatility shocks that have little to do with the highly persistent component of volatility captured by standard volatility models.

Slopes as Factors: Characteristic Pure Plays

Returns to pure play strategies, estimated as Fama-MacBeth slope coefficients on standardized size, value and momentum characteristics, have positive and significant four factor alphas. The mispricing of these characteristics-based strategies by the four factor model is due in part, but not entirely, to (1) the effect of microcap stocks on the pure play returns and (2) the effect of stale book and market capitalization information on the SMB and HML factors. Adjusting for these issues, the value and momentum pure play strategies still have positive and significant four factor alphas. We examine thirteen reported anomalies and find that five have insignificant alphas when the pure play returns are used as factors. Eight are insignificant when an interaction between size and value characteristics is included as a factor.

Bootstrap Tests of Multiple Inequality Restrictions on Variance Ratios

We develop a block bootstrap method for testing multiple inequality restrictions on variance ratios. The proposed test has reasonable size and power in the presence of strong persistence in conditional variances, making it well suited to applications in financial econometrics.

Testing Factor Models on Characteristic and Covariance Pure Plays

We test the recent Fama-French five-factor model and Hou-Xue-Zhang four-factor model using test assets from Fama-MacBeth regressions, which are pure plays on particular characteristics or covariances. Our tests resolve the errors-in-variable bias in Fama-MacBeth regressions with estimated betas. Monte Carlo evidence shows that the tests are unbiased even with time-varying stock betas and characteristics. For both factor models, characteristic pure plays generally have positive alphas, and covariance pure plays have negative alphas. The models fail especially in explaining returns to investment and when pure plays are momentum-neutral. The rejections are economically significant.