三种度量基准下的无风险利率实证比较

以上证综指、深圳成指和沪深300指数为研究样本,构建了多因子模型,并利用2003年1月—2009年2月三类指数收益率及各因子的月度数据,用最小二乘法实证反演了上海证券交易市场、深圳证券交易市场以及沪深综合证券交易市场隐含的无风险利率和风险价值。研究发现:股市隐含的风险补偿为负,与传统的风险溢价理论相悖;以短期银行存款利率、7天Shibor利率及7天国债回购利率为度量基准,股市隐含的无风险利率与其存在较大差异,因此在金融衍生品等相关研究中不宜不加选择地将它们作为无风险利率的代理指标。     

Are Dow Jones Islamic equity indices exposed to interest rate risk?

The Dow Jones Islamic Market indices (DJIMI) are constructed by screening out stocks that are incompatible with Islam's prohibition of interest and certain lines of business. However, as a blunt instrument, the interest rate can affect discounted cash flows of any firm, even a firm with no financial leverage. This study reveals that the aggregate portfolio of Islamic stocks is immune to interest rate risk. However, at the sectoral level some Islamic equity portfolios demonstrate exposure to interest rate risk. Overall, evidence of interest rate risk exposure is less pronounced among Islamic sector portfolios than that of their mainstream counterparts—the Dow Jones World sector indices. The results also hold when interest rate risk is assessed in terms of the sensitivity of the DJIMI return to changes in level, slope and curvature of the interest rate term structure.     

Optimizing tracking error-constrained portfolios

Active portfolios subject to tracking error (TE) constraints are the typical setup for active managers tasked with outperforming a benchmark. The risk and return relationship of such constrained portfolios is described by an ellipse in traditional mean-variance space and the ellipse’s flat shape suggests an additional constraint which improves the performance of the active portfolio. Although subsequent work isolated and explored different portfolios subject to these constraints, absolute portfolio risk has been consistently ignored. A different restriction – maximization of the traditional Sharpe ratio on the constant TE frontier in absolute risk/return space – is added here to the existing constraint set, and a method to generate this portfolio is explained. The resultant portfolio has a lower volatility and higher return than the benchmark, it satisfies the TE constraint and the ratio of excess absolute return to risk is maximized (i.e. maximum Sharpe ratio in absolute space).     

Fuzzy possibilistic portfolio selection model with VaR constraint and risk-free investment

We propose a possibilistic portfolio model with VaR constraint and risk-free investment based on the possibilistic mean and variance, while assuming that the expected rate of returns is a fuzzy number. The model shows more clearly that, in the financial market affected by several non-probabilistic factors, risk-averse investors wish not only to reach the expected rate of returns in their actual investment, but also to assure that the maximum of their possible future risk is lower than an expected loss. Under the condition that the expected rate of returns is a normal distribution fuzzy variable, we proposed a theorem as the solution, and derive a crisp equivalent form of the possibilistic portfolio under constraints of VaR and risk-free investment. This model is an expansion of the fuzzy possibilistic mean–variance model by Zhang (2007). Finally, an empirical study is carried out using the data concerning some stocks of various industries listed at the Shanghai Stock Exchange. A conclusion is reached that the investors are able to choose a portfolio more suitable to them under the VaR constraint.     

Option implied beta and option return

We study the information content of option-implied betas for future equity option returns, using data on the S&P 500 index options and all of the component stock options. We find a significantly strong relation between option-implied betas and option returns cross-sectional. The paper presents evidence that call (put) option returns increase (decrease) with the option-implied betas of the underlying stock. A trading strategy of buying high (low) implied beta call (put) option portfolio and selling low (high) implied beta call (put) option portfolio generates a statistically and economically significant return. Our results are robustly persistent even after controlling for various cross-sectional effects and are not explained by the risk factors in asset pricing.     

Increasing returns to savings and wealth inequality

In this paper I present an explanation to the fact that in the data wealth is substantially more concentrated than income. Starting from the observation that the composition of households' portfolios changes towards a larger share of high-yield assets as the level of net worth increases, I first use data on historical asset returns and portfolio composition by wealth level to construct an empirical return function. I then augment an Overlapping Generation version of the standard neoclassical growth model with idiosyncratic labor income risk and missing insurance markets to allow for returns on savings to be increasing in the level of accumulated assets. The quantitative properties of the model are examined and show that an empirically plausible difference between the return faced by poor and wealthy agents is able to generate a substantial increase in wealth inequality compared to the basic model, enough to match the Gini index and all but the top 1 percentile of the US distribution of wealth.     

Portfolio choice with high frequency data: CRRA preferences and the liquidity effect

This paper suggests a new approach for portfolio choice. In this framework, the investor, with CRRA preferences, has two objectives: the maximization of the expected utility and the minimization of the portfolio expected illiquidity. The CRRA utility is measured using the portfolio realized volatility, realized skewness and realized kurtosis, while the portfolio illiquidity is measured using the well-known Amihud illiquidity ratio. Therefore, the investor is able to make her choices directly in the expected utility/liquidity (EU/L) bi-dimensional space. We conduct an empirical analysis in a set of fourteen stocks of the CAC 40 stock market index, using high frequency data for the time span from January 1999 to December 2005 (seven years). The robustness of the proposed model is checked according to the out-of-sample performance of different EU/L portfolios relative to the minimum variance and equally weighted portfolios. For different risk aversion levels, the EU/L portfolios are quite competitive and in several cases consistently outperform those benchmarks, in terms of utility, liquidity and certainty equivalent.     

A large CVaR-based portfolio selection model with weight constraints

Although the traditional CVaR-based portfolio methods are successfully used in practice, the size of a portfolio with thousands of assets makes optimizing them difficult, if not impossible to solve. In this article we introduce a large CVaR-based portfolio selection method by imposing weight constraints on the standard CVaR-based portfolio selection model, which effectively avoids extreme positions often emerging in traditional methods. We propose to solve the large CVaR-based portfolio model with weight constraints using penalized quantile regression techniques, which overcomes the difficulties of large scale optimization in traditional methods. We illustrate the method via empirical analysis of optimal portfolios on Shanghai and Shenzhen 300 (HS300) index and Shanghai Stock Exchange Composite (SSEC) index of China. The empirical results show that our method is efficient to solve a large portfolio selection and performs well in dispersing tail risk of a portfolio by only using a small amount of financial assets.     

艺术品的金融属性：投资收益与资产配置*

本文基于2000—2014年中国艺术品拍卖市场近现代国画的微观数据,在资产配置中引入市场交易机制中的佣金变量,加入艺术品市场规模约束,采用重复交易法实证计量嵌入艺术品市场的投资收益特征并量化其资产配置效应,以测度其市场功能。优质的艺术精品具备金融资产风险和收益的基本特征,本文对艺术品资产与资本资产定价模型的适应性进行讨论。研究表明：在样本期内,剔除通胀和佣金成本因素后收益率更加贴近现实,中国艺术品投资的实际收益率水平为1308%,表现出高于欧美市场的投资溢价;艺术品投资与传统的股票、债券等金融资产之间表现出相对独立性,并能有效改善投资者资产组合的风险边界,可以成为资产配置优化和多样化的重要选择。中国艺术品市场的长期稳健发展将为投资者提供更多的资产优化产品和工具。     

Modelling VaR for foreign-asset portfolios in continuous time

VaR is widely viewed as a measure of market risk of a portfolio. The purpose of this article is to provide a VaR model for foreign-asset portfolios in continuous time. In the VaR model, the VaRs are not only a function of volatilities of asset returns and exchange rate but also a function of correlation coefficient between foreign assets and exchange rate. Moreover, by backtesting, the empirical results show that the new VaR model can efficiently evaluate the market risk of foreign-asset portfolios.     

Unilateral CVA for CDS in a contagion model with stochastic pre-intensity and interest

Price of a financial derivative with unilateral counterparty credit risk equals to the price of an otherwise risk-free derivative minus a credit value adjustment (CVA) component, which can be seen as a call option on investor's NPV with strike 0. Thus modeling volatility of NPV is the foundation for CVA valuation. This paper assumes that default times of counterparty and reference firm follow a special contagion model with stochastic pre-intensities that allows for explicit formulas for default probabilities. Stochastic interest rate is also incorporated to account for positive correlation between pre-intensity and interest. Survival measure approach is employed to calculate NPV of a risk-free CDS, and semi-analytical solution for CVA is obtained through affine specifications. Numerical analysis shows that contagion has more significant impact on CVA than diffusion of pre-intensities, and the positive correlation between interest and reference firm's pre-intensity has monotonic decreasing impact on CVA.     

Endogenous Home Bias in Portfolio Diversification and Firms’ Entry

The home bias in portfolios is considered a main puzzle in international macroeconomics. This paper provides a new benchmark for its analysis in a tractable new open economy macroeconomic model, where the home‐biased position is an optimal allocation. An equilibrium model of perfect risk‐sharing is specified, with endogenous portfolios and firm entry. Unlike in previous work, the international portfolio diversification is driven by home bias in capital goods—independently of home bias in consumption when countries are of equal size. The model explains the recent patterns of portfolio allocations in developed economies. Most important, optimal portfolio shares are independent of market dynamics.     

Enhanced index tracking with multiple time-scale analysis

This paper considers the process optimal strategies for an enhanced index tracking problem. The investment goals are set to achieve a higher return than the benchmark by setting the portfolio's risk profile identical to the primary index risk factors. Return differences between the index and the tracking portfolio are classified as positive and negative series. Multiple time-scale features of each series are extracted by the method of empirical mode decomposition. Then the positive return deviations are modeled by trend-like low frequency behavior and the negative return deviations are modeled by a trendless high frequency behavior. By adopting an immunity-based multi-objective optimization algorithm, the solutions for the process optimal enhanced index tracking are developed. Five data sets drawn from major world markets are adopted to implement our approach. The computational results show the superiority of our model.     

Systematic skewness in asset pricing: an empirical examination of the Taiwan stock market

This paper is an empirical study of asset pricing with the systematic skewness in the pricing model. We adopt the Fama-French three-factor model, which incorporates the firm-size and book-to-market ratio in asset pricing as the base case, and then includes the skewness factor used by Harvey and Siddique in the pricing model. The evidence shows that systematic skewness is significant and might be important in asset pricing when portfolios are formed by industry, firm-size, book-to-market, or momentum strategies. When portfolios are constructed by momentum or coskewness strategies, lower momentum, or lower coskewness portfolios exhibit higher skewness and higher kurtosis. When portfolios are grouped by excess returns, it is seen that the average excess return is positively correlated with size and coskewness. Thus the systematic skewness is closely related to firm size. And the relationship between systematic skewness and excess return is obscured by the reverse firm-size effect.     

资产选择、风险偏好与储蓄存款需求

本文以消费者最优资产选择模型为基础,采用局部均衡分析方法探讨了通货膨胀、股市收益波动、消费者风险偏好对储蓄存款需求的影响。2001年6月以后,通货膨胀方差下降,股市持续下跌,股市收益率下降,收益率方差也有所下降,但货币需求却加速增长。本文根据不同的相对风险回避指数,模拟了利率、通货膨胀、股市收益率、股市收益率方差等因素对2001年6月至2005年9月平均储蓄存款的影响。在适当的相对风险回避指数下,储蓄存款增加的30%左右可以由这些因素解释;如果不考虑GDP等规模变量,股市收益率下降是导致平均货币需求增长的主要因素。     

Optimal portfolio selection with maximal risk adjusted return

We investigate the portfolio diversification problem by maximizing the risk adjusted return (RAR) of the underlying portfolio. The model in this article has two primary advantages over the original portfolio selection model with maximal RAR: (1) it considers the set of available assets containing any number of assets instead of only two assets, which is more reasonable in practical applications and (2) it incorporates the general linear constraint other than the simple budget constraint, which can deal with additional constraints for rational investors. An application including in-sample and out-of-sample tests is provided where the results illustrate that the portfolios selected by our method lead to considerable increases of RAR in comparison with those by the minimization of variance approach, and the outperformance persists using different sample frequencies.     

基于Poisson跳跃的信用价差期权定价

信用价差是用以向投资者补偿参照资产违约风险的、高于无风险利率的利差。信用价差期权作为风险控制的重要手段之一,其定价也日益得到人们的关注。现有文献几乎是单纯地利用几何布朗运动来刻画资产的价格变化过程从而对信用价差期权进行定价。而在实际中会出现某些不寻常的事件导致资产价格出现不间断的跳跃现象,普通的定价方法对这种现象的解释力度不够。因此本文引入Poisson跳跃来描述信用价差变化过程中的异常情况,更好地解释当遇到金融危机等情况时资产价值的跳跃现象。由于Longstaff和Schwartz的模型引入了随机利率,可以给出定价公式的封闭解析解的优点,本文在此模型上进行进行研究,将刻画信用价差动态过程的O-U过程与Poisson跳跃结合,利用伊藤公式进行推导并引入了利率的平方根过程,得到了欧式信用价差期权的定价公式,更好地考虑了资产价格的跳跃情况。     

Stochastic growth: a duality approach

We re-examine the representative agent's optimal consumption and savings under uncertainty in the presence of investment constraints using martingale representation and convex analysis techniques. This framework allows us to explicitly quantify precautionary savings which induces a higher average growth rate than in a certainty setup. We provide a closed form solution for a Cobb-Douglas economy. The effect of uncertainty on portfolio selection is analyzed. Consumption growth rate and risk free interest rate exhibit a U-shaped relationship. Uncertainty negatively affects expected consumption growth rate; such a result seems to be supported by empirical evidence.     

Stochastic optimization applied to self-financing portfolio: does bequest matter?

The article studies stochastic optimization of an intertemporal consumption model to allocate financial assets between risky and risk-free assets. We use a stochastic optimization technique, in which utility is maximized subject to a self-financing portfolio constraint. The papers in literature have estimated the errors of Euler equations using data from financial markets. It has been shown that it is sufficient to test the first order Euler equation implied by the model. However, they all assume a constant consumption–wealth ratio that constrains the boundary conditions, hence influencing the coefficient of the risk premium. The main contribution of our article is that we drop the assumption of a constant consumption–wealth ratio. We have an analytical solution using a utility maximization model with a stochastic self-financing portfolio. We introduce a terminal condition of wealth with and without bequests. We also simulate the stochastic optimization with a self-financing portfolio, distinguishing risk neutral investors (γ-low) from high risk averse investors (γ-high). We show that the model with bequest has a higher level of wealth and a smoother decline of consumption over time than the model with no bequest at the end of the period. The model with no bequest has the same level of consumption and a sharp fall at the end of the period. Risk averse agents with high return assets have a higher amount of wealth than risk-neutral agents with lower return assets.     

Vertical alliance portfolios and the business performance of small technology-based firms

This paper discusses how small technology-based firms (STBFs) effectively manage vertical alliances by choosing proper alliance structures to both manage challenges and pursue higher performance. We consider the main challenges of STBFs’ vertical alliances as opportunistic risk and coordination concern between partners, and derive four types of vertical alliance portfolios with different extents of risk and return based on the relational perspective. We then examine the impact of each portfolio on performance and the moderating effect of STBFs’ age and technological capability. The results show the portfolio focusing on bilateral alliances is not helpful for STBFs, while the others are useful. The portfolio focusing on unilateral alliances promises young firms better performance, while hybrid portfolios of unilateral and bilateral alliances are more helpful for older STBFs. In hybrid portfolios, bilateral alliance in the upstream is beneficial to specific technology-focused firms, while bilateral alliance in the downstream is recommended to STBFs whose technology covers a wider range.