On the implied market price of risk under the stochastic numéraire

This papers addresses the stock option pricing problem in a continuous time market model where there are two stochastic tradable assets, and one of them is selected as a numéraire. An equivalent martingale measure is not unique for this market, and there are non-replicable claims. Some rational choices of the equivalent martingale measures are suggested and discussed, including implied measures calculated from bond prices constructed as a risk-free investment with deterministic payoff at the terminal time. This leads to possibility to infer a implied market price of risk process from observed historical bond prices.     

Past managerial guidance and returns to variance trading around earnings announcements

I investigate the relationship between past managerial guidance and realized variance risk premiums (VRPs) – i.e., the difference between implied and realized variance – in equity options around earnings announcements. I find that implied variances are lower before earnings announcements but VRPs are higher when firms provide guidance. I also find higher option-implied jump risk when firms issue surprising guidance. Further tests suggest a portion of the higher VRPs are due to changes in perceived higher-order risks, but traders also underreact to the precision of information in short-term guidance. These results are attenuated for firms with a better information environment.     

Individual home bias,portfolio churning and performance

This study investigates economic consequences of individual investors’ home bias and portfolio churning in their personal pension accounts. The empirical analysis is carried out within a Heckman style two-stage framework to account for selection bias with respect to individuals’ investment activity, and to allow for an endogenously determined home bias, portfolio churning and performance. Results indicate that home bias induces a worse risk-adjusted performance. Home-biased individuals’ relatively bad performance originates in insufficient risk-reduction, due to a lack of international diversification. A higher degree of portfolio churning also deteriorates performance, despite the fact that churning is not associated with any direct transaction costs. However, home-biased individuals do not churn portfolios as often as individuals with a larger share of international asset holdings, which diminishes the negative effects of home bias on performance. Overconfidence is driven by a return-chasing behavior, where overconfident individuals favor international assets with high historical returns. Individuals with actual skill are more often men than women, are not tempted by high historical returns, and use international assets for the right reason – diversification.     

Modern portfolio management with conditioning information

This paper studies models in which active portfolio managers utilize conditioning information unavailable to their clients to optimize performance relative to a benchmark. We derive explicit solutions for the optimal strategies with multiple risky assets, with or without a risk-free asset, and consider various constraints on portfolio risks or weights. The optimal strategies feature a mean–variance efficient component (to minimize portfolio variance), and a hedging demand for the benchmark portfolio (to maximize correlation with the benchmark). A currency portfolio example shows that the optimal strategies improve the measured performance by 53% out of sample, compared with portfolios ignoring conditioning information.     

Positively Weighted Portfolios on the Minimum-Variance Frontier

Duality theory is employed to provide necessary and sufficient conditions for portfolios on the minimum-variance frontier to have positive investment proportions in all assets. These conditions involve the feasibility of portfolios that have non-negative correlation with all assets and positive correlation with at least one. Using these results, several “qualitative” results concerning the signs of investment proportions in efficient portfolios are proved. It is argued that the conditions that ensure all-positive weights in efficient portfolios are intuitively compelling and are not unique to the CAPM. With large numbers of assets, however, the signs of weights in minimum-variance portfolios can be very sensitive to slight departures from these conditions due to, for example, sampling error.     

新常态下的居民投资理财研究——基于均值-方差模型下的大类资产配置

随着《关于规范金融机构资产管理业务的指导意见》的落地,我国资产管理行业的发展进入了新常态。我国居民的投资期限及投资工具将发生明显变化,包括:产品投资期限可能大幅延长;投资工具的主要形态将由传统的预期收益型理财产品转化为净值型产品。本文重点探讨在行业管理新规的新常态下,居民如何通过合理的大类资产配置实现有效投资。本文在均值-方差模型(Mean-Variance Model)的基础上,结合过去12年我国股票、债券、货币、黄金和国债五大类资产的投资数据,构建有效边界(Efficient Frontier),并在此基础上寻得夏普比率(Sharpe Ratio)最高的风险资产组合,进而绘制资本市场线(Capital Market Line)。通过对资本市场线及有效边界上若干组合的实证检验,本文发现:通过对大类资产的合理组合,可以为投资者带来长期稳定的投资回报;因流动性需求,投资者进行中短期投资时,低预期收益目标的投资组合表现更优。     

The diversification effects of volatility-related assets

We examine whether investors can improve their investment opportunity sets through the addition of volatility-related assets into various groupings of benchmark portfolios. By first analyzing the weekly returns of three VIX-related assets over the period 1996-2008 and then applying mean-variance spanning tests, we find that adding VIX-related assets does lead to a statistically significant enlargement of the investment opportunity set for investors. Our empirical findings are robust and have two implications. First, there is scope for the further development of financial products relating to volatility indexes. Second, hedge fund managers can utilize VIX futures contracts or VIX-squared portfolios to enhance their equity portfolio performance, as measured by the Sharpe ratio.     

Option-implied expectations in commodity markets and monetary policy

In this paper we estimate the dynamic interactions between option-implied variance and skewness in agricultural commodity markets and monetary policy. Using a structural vector autoregressive (SVAR) framework, we find that an expansionary (contractionary) monetary policy upwardly (downwardly) revises commodity markets’ expectations about the price and volatility path of agricultural products. On the other hand, our empirical analysis reveals that monetary policy does not have a systematic and timely response to sudden changes in option implied expectations of commodity investors. In addition, we provide empirical evidence showing the robust forecasting power of agricultural option-implied information on monetary policy with R² values reaching almost 52%.     

Dynamic conditional copula correlation and optimal hedge ratios with currency futures

This study investigates efficiency of the futures hedge implemented through the currency markets. The copula DCC-EGARCH model is estimated with the bivariate error correction term to minimize variance of the currency portfolios. The estimation results for the currencies of the Australian dollar, Canadian dollar, euro, British pound and Japanese yen show that the inclusion of the external realized variance estimators into the variance equation of the estimated model improves the model's ability to account for the clustered data variance. In hedging portfolios, the information content of the realized variance estimator effectively reduces the variance of the portfolios.     

Would emerging market pension funds benefit from international diversification: investigating wealth accumulations for pension participants

In recent years, investment portfolio selection is growing in importance for many emerging market pension funds, as pension reforms replace traditional pay-as-you-go systems with advanced funding systems. Various investment regulations are applied to the funded pensions, particularly in the form of portfolio limits for equities and international assets. With a bootstrap simulation approach, this paper attempts to quantify the impacts on retirement benefits of restricting international assets from the investment portfolios of emerging market pension funds. We find that, on average, over half of the pension portfolios of emerging market countries should be in international assets in order to maximize the expected utility of moderate and conservative pension fund participants. More generally, international assets can play a significant role in the investment portfolios for workers with risk aversion varying from aggressive to conservative. With few exceptions, the entire probability distribution of wealth accumulations at retirement could be shifted higher with the inclusion of international assets.     

The Efficient Use of Conditioning Information in Portfolios

We study the properties of unconditional minimum-variance portfolios in the presence of conditioning information. Such portfolios attain the smallest variance for a given mean among all possible portfolios formed using the conditioning information. We provide explicit solutions for n risky assets, either with or without a riskless asset. Our solutions provide insights into portfolio management problems and issues in conditional asset pricing.     

The information content of option-implied information for volatility forecasting with investor sentiment

This study explores the effect of investor sentiment on the volatility forecasting power of option-implied information. We find that the risk-neutral skewness has the explanatory power regarding future volatility only during high sentiment periods. Furthermore, the implied volatility has varying volatility forecasting ability depending on the level of investor sentiment. Our findings suggest that the effectiveness of volatility forecasting models based on option-implied information varies over time with the level of investor sentiment. We confirm the important role of investor sentiment in volatility forecasting models exploiting option-implied information with strong evidence from in-sample and out-of-sample analyses. We also present improvements in the accuracy of volatility forecasts from volatility forecasting models derived by incorporating investor sentiment in these models.     

Econometrics of efficient fitted portfolios

In this paper we propose a mean variance analysis of the portfolio choice under constraints. An efficient portfolio under constraint is called fitted. We show that the fitted portfolios can consistently be estimated and used to assess the performances of the portfolio management. The explicit formula of the individual demand function for assets is also derived, and generalizes the demand function of the standard portfolio choice theory. The performance measures and associated statistics can be used to test the hypothesis of the portfolio efficiency under constraint. Moreover, we explain how to estimate subsets of constraints faced by an individual. Finally, we show that our framework is also adequate for the analysis of incomplete information.     

Capital market equilibrium with heterogeneous investors

As a two-parameter model that satisfies stochastic dominance, the mean-extended Gini model is used to build efficient portfolios. The model quantifies risk aversion heterogeneity in capital markets. In a simple Edgeworth box framework, we show how capital market equilibrium is achieved for risky assets. This approach provides a richer basis for analysing the pricing of risky assets under heterogeneous preferences. Our main results are: (1) identical investors, who use the same statistic to represent risk, hold identical portfolios of risky assets equal to the market portfolio; and (2) heterogeneous investors as expressed by the variance or the extended Gini hold different risky assets in portfolios, and therefore no one holds the market portfolio.     

Conditional portfolio allocation: Does aggregate market liquidity matter?

This paper investigates how aggregate liquidity influences optimal portfolio allocations across various US characteristic portfolios. We consider short-term allocation problems, with single and multiple risky assets, and use the nonparametric approach of Brandt (1999) to directly express optimal portfolio weights as functions of aggregate liquidity shocks. We find, first, that the effect of aggregate liquidity is positive and decreasing with the investment horizon. Second, at daily and weekly horizons, this effect is weaker on allocations in large stocks and gets stronger as we move toward small stocks, regardless of the other stock characteristics, suggesting that liquidity is the main concern of very short-term investors. Third, conditional allocations in risky assets decrease and exhibit shifts toward more liquid assets as aggregate liquidity worsens. Overall, conditioning on aggregate liquidity yields empirical results that are consistent with the so-called flight-to-safety and flight-to-liquidity episodes. Finally, we propose a simple tactical investment strategy and show how aggregate liquidity information can be exploited to enhance the out-of-sample performance of long-term strategies.     

International capital market equilibrium with investment barriers

This paper outlines models of capital market equilibrium when there are explicit barriers to international investment in the form of a tax on holdings of assets in one country by residents of another country. There is a corresponding subsidy on short positions in foreign assets. Asset prices deviate from the predictions of the world capital asset pricing model. Investors do not hold a mixture of national market portfolios, but the mix of risky assets is the same for every investor in a country. Optimal portfolios tend to be heavy in domestic assets, and light in foreign assets. Tax free investors, however, tend to hold assets anywhere in the world that are taxed heavily. Estimates of the magnitude of the average tax (or the magnitude of effective barriers to international investment) can be made by comparing the average return on the minimum variance zero β portfolio, z, with the average across countries and time of the short-term interest rate. When barriers are ineffective, the expected return on portfolio z will be the average short-term interest rate, and the world capital asset pricing model will hold.     

Performance of mutual funds before and after closing to new investors

This study examines the decision to close mutual funds to new investors due to the growth of the funds' assets. The evidence indicates that funds perform better three years prior to closing to new investors than they do afterwards. Furthermore, the evidence indicates that the closed funds outperform the control portfolios of funds with similar investment objectives and asset size during the one- and three-year periods prior to closing. However, there is no significant difference in the performance of closed funds and their matched control portfolios during the one- and three-year periods after closing. Although the primary reason given for closing the funds is the desire to maintain performance in the face of growing assets, the strategy does not appear successful in accomplishing this objective.     

Myopic loss aversion and stock investments: An empirical study of private investors

Myopic loss aversion was suggested by Benartzi and Thaler (1995) as an explanation for the equity premium puzzle. Its main prediction is that loss averse investors, who evaluate their investment performance too frequently and therefore often observe small losses on their stock portfolios, would invest too little in equity. We investigate the link between myopic loss aversion and actual investment decisions of individual investors, using survey data. Our results are consistent with the predictions of Benartzi and Thaler. Higher myopic loss aversion is associated with lower stock investment as a share of total assets. Investors tend to evaluate their stock portfolio performance too often, which contributes to the prevalence of myopic loss aversion. The effect of myopia is most apparent when investors both evaluate their portfolios frequently and trade stocks regularly.     

Dynamic Investment Strategy with Factor Models Under Regime Switches

A model for dynamic investment strategy is developed where assets’ returns are represented by multiple factors. In a mean–variance framework with factor models under regime switches, we derive a semi-analytic solution for the optimal portfolio with transaction costs. Due to the existence of transaction costs, the optimal portfolio is characterized as a linear combination of current and target portfolios, the latter of which maximizes the value function in the current regime. For some special cases of interest, we also derive simplified analytical solutions. To see the effect of regime switches, the proposed model is applied to US equity market in which small minus big and high minus low are employed as factors. Investment strategy based on our model demonstrates empirically that the regime switching models exhibit superior performance over the single regime model for such performance measures as realized utility and Sharpe ratio which are of particular interest in practice. Taking a close look at the time series of portfolio returns, the result shows the usefulness of the regime switching model as investors flexibly optimize asset allocations depending on the state of the market.