投资组合行业配置的动态VaR研究——基于时变Copula-GJR-Skewed-t模型

用时变Copula-GJR-Skewed-t模型研究了深证22个行业分类指数中任意两个投资组合的动态VaR,并与静态VaR比较。实证结果表明,时变t-Copula函数在众多Copula函数中对行业投资组合的拟合效果最优,给出了模型估计出的VaR最大和最小的5对行业组合,不同行业组合的动态VaR在股市周期各阶段关系相对稳定,同一行业组合的动态VaR和静态VaR关系相对稳定,且略高于静态VaR。     

基于Copula-GARCH-EVT的中国开放式基金投资组合风险度量

文章结合CARCH模型和EVT理论刻画了单个金融资产收益率的波动性和尾部分布,并将Copula函数和Monte Carlo技术应用于证券投资组合的VaR计算方法.通过对光大红利基金的实证研究,得到前十大重仓中单只股票及其投资组合的风险值,结果表明,基于Copula-GARCH-EVT的VaR方法具有重要的经济应用价值.     

基于Copula理论的商业银行的市场风险研究

在投资者看好银行股的背景下,结合t-EGARCH模型和极值理论,利用Copula方法对14家上市银行股票进行分析,并通过蒙特卡洛模拟计算单只股票以及投资组合的VaR.结果表明,此方法能很好地量化风险,有助于衡量市场风险.     

中国开放式基金投资组合风险值的实证——基于Copula-GARCH的分析

结合Copula技术和GARCH模型,建立了投资组合风险分析的Gopula-GARCH模型.由于该模型可以捕捉金融市场间的非线性相关性,因而可用于投资组合VaR的分析.利用这个模型,结合Monte Carlo,模拟技术,对我国第一支开放式基金一华安创新基金的投资组合进行了风险分析.     

基于Copula-VaR的金融资产组合风险测度研究

引入Copula函数来改进传统的VaR方法,构建出Copula-VaR模型。通过蒙特卡罗模拟实证金融资产组合收益的各种VaR值,结果表明,Copula-VaR模型能够更精确地测度出金融资产组合的在险价值风险。     

资产组合风险的极值Copula模型与实证研究

本文在极值理论POT模型的基础上,引入了Copula连接函数,建立极值Copula模型,给出了组合风险价值VaR的计算公式,并以加元和日元回报为样本进行了实证分析,结果表明,极值Copula模型能较好地度量资产组合的风险,直接加权的方法会高估风险,假设资产组合服从多元正态分布会低估风险。     

基于GARCH-EVT-Copula的社保基金投资组合风险测度研究

社保基金是社会保障事业健康发展的物质基础,安全性是其投资的首要原则。文章基于GARCH-EVT-Copula方法测度了社保基金投资组合的VaR。首先,基于GARCH、EVT对投资组合中各金融资产收益的边缘分布建模,然后,采用极大似然估计法和Bootstrap方法估计尾部的分布函数,接着,基于Copula方法研究组合中金融资产间的相关结构,最后,运用Monte Carlo方法测度投资组合的VaR。Kupiec检验表明,基于GARCH-EVT-Copula模型测度社保基金投资组合的风险是合适的。     

基于EGARCH-Copula模型的VaR方法在投资组合风险分析中的应用

GARCH族模型是金融计量学中用来描述或预测金融资产收益率波动的模型,通过对金融资产收益率波动的建模,可以得出未来金融资产收益率的条件分布。Copula函数可以用来描述多个随机变量间的相依结构,进而得出他们的联合分布。Copula自被引入金融产品分析以来,以取得了很多成果也被广泛使用。运用GARCH族模型进行资产组合中边缘分布的建模,继而使用Copula得到组合资产联合分布的方法来计算资产组合VaR值最早被吴振翔（2006）系统性地提出,但其中有许多问题仍需要完善。本文将继续这个思路,通过EGARCH模型更好地描述资产收益率的杠杆效应,以及考虑Copula函数中参数的时变性,来完善这一方法。     

我国开放式基金业绩评价的实证研究——基于VaR的业绩评价方法与三大经典评价方法的比较分析

现代投资理论认为,只有经风险调整后的收益才可以作为相互比较的基础来评价投资基金的投资业绩.因此,基金业绩评价的核心应该是对其所面临的风险进行准确的计量.通过对我国开放式基金应用基于VaR的评价方法与三大经典评价方法进行业绩评价的比较分析发现,从投资者注重下跌风险的角度来看,基于VaR的基金业绩评价指标相对于三大经典指标有较明显的应用优势,投资者又多一种能符合自己风险偏好的评价指标作为投资参考.     

一种计算投资组合VaR的新方法

作为金融领域一个重要研究课题,风险度量受到越来越多的关注。传统的估计风险值的方法检验效果不理想,本文运用Copula函数代替相关系数表示风险因子之间的依存关系,能够有效地处理投资组合的风险和相关性,并通过实证分析运用Copula理论来计算投资组合收益风险值。     

基于Copula的投资组合选择模型研究

基于概率收益率与概率风险的定义,建立基于风险与收益率的投资组合模型,为了更好拟合联合分布,在具体解法中采用Copula函数来构造多个资产收益率的联合分布。由于不要求收益率服从维纳过程,因此基于Copula的Markowitz投资组合选择模型具有更广的适用性。通过对上证领先指数与深证领先指数收盘数据实证分析发现,在收益率(基于概率ρ0的收益率)一定的情况下,通过投资组合可以降低风险。     

Hedge funds and optimal asset allocation: Bayesian expectations and spanning tests

This paper analyzes the contribution of hedge funds to optimal asset allocations between 1993 and 2010. The preferences of specific institutional investors are captured by implementing a Bayesian asset allocation framework that incorporates heterogeneous expectations regarding hedge fund alpha. Mean-variance spanning tests are used to infer the ability of hedge funds to significantly enhance the mean-variance efficient frontier. Further, a novel democratic variance decomposition procedure sheds light on the dynamics in the co-movement of hedge fund returns with a set of common benchmark assets. The empirical findings indicate that portfolio benefits of hedge funds are time-varying and strongly depend on investor optimism regarding hedge funds’ ability to generate alpha. In general, allocations to hedge funds improve the global minimum variance portfolio even after controlling for short-selling restrictions and minimum diversification constraints. However, due to dynamics underlying the composition of the aggregate hedge fund universe, the factor structure of hedge fund returns has become more similar to the benchmark assets over time.     

Polynomial goal programming and the implicit higher moment preferences of US institutional investors in hedge funds

Polynomial goal programming (PGP) is a flexible method that allows investor preferences for different moments of the return distribution of financial assets to be included in the portfolio optimization. The method is intuitive and particularly suitable for incorporating investor preferences in higher moments of the return distribution. However, until now, PGP has not been able to meet its full potential because it requires quantification of “real” preference parameters towards those moments. To date, the chosen preference parameters have been selected somewhat “arbitrarily”. Our goal is to calculate implied sets of preference parameters using investors’ choices of and the importance they attribute to risk and performance measures. We use three groups of institutional investors—pension funds, insurance companies, and endowments—and derive implied sets of preference parameters in the context of a hedge fund portfolio optimization. To determine “real” preferences for the higher moments of the portfolio return distribution, we first fit implied preference parameters so that the PGP optimal portfolio is identical to the desired hedge fund portfolio. With the obtained economically justified sets of preference parameters, the well-established PGP framework can be employed more efficiently to derive allocations that satisfy institutional investor expectations for hedge fund investments. Furthermore, the implied preference parameters enable fund of hedge fund managers and other investment managers to derive optimal portfolio allocations based on specific investor expectations. Moreover, the importance of individual moments, as well as their marginal rates of substitution, can be assessed.     

保险资金的证券投资绩效分析

本文回顾了保险资金在证券投资领域的政策变化历程,分析了保险资金运用效率与基金业绩评价的诸多不同,指出了基于资产组合优化理论的保险资金评价方法的不足,提出用影子组合法,作为一种正向制度激励,对保险资金运用效率进行评价,并基于该方法对三家上市保险公司的资金运用效率进行了比较。     

基于Copula的股票市场波动溢出分析

对于动态投资组合与风险管理来说,测定波动溢出效应是非常重要的。已有的研究是建立在不同金融市场之间的波动是线性相关的,而线性相关并不能描述金融市场之间的非线性关系。借用Copula技术来描述股票市场之间的非线性关系、SV模型来刻画股票市场数据的边缘分布,并引入波动变结构论分析判断波动溢出,实证分析验证了方法是可行的。     

投资组合构建与调整的合理性及其对基金绩效的影响

从理论推论看,投资组合构建与调整的合理性越高,投资绩效就可能越好。为此,本文构建了衡量组合合理性高低的指标,并采用Kolmogorov-Smirnov检验法、Kruskal-Wallis检验法、基于Wilcoxon秩检验的多重比较法等方法,实证研究我国股票型基金投资组合的合理性对基金绩效的影响。研究结果一方面支持了理论推论的正确性,另一方面也印证了本文所建立的组合合理性指标的可取性。同时论文发现,在牛市熊市的不同情况下,基金组合构建的合理性及其对继续的影响存在差异。论文据此提出了相关的建议和启示。     

Measuring bond mutual fund performance with portfolio characteristics

This paper studies the performance of U.S. bond mutual funds using measures constructed from a novel data set of portfolio weights. Active fund managers exhibit outperformance before costs and fees generating, on average, gross returns of 1% per annum over the benchmark portfolio constructed using past holdings (approximately the same magnitude as expenses and transaction costs combined). This suggests that fund managers are able to earn back their fees and costs. There is evidence of neutral ability to time different portfolio allocations (sector, credit quality, and portfolio maturity allocations) and only a subgroup of bond funds exhibit successful timing ability. One performance measure based on portfolio holdings predicts future fund performance and provides information not contained in the standard measures. These results provide the first evidence of the value of active management in bond mutual funds.     

Hedge fund allocation: Evaluating parametric and nonparametric forecasts using alternative portfolio construction techniques

We propose a model for constructing Asian funds of hedge funds. We compare the accuracy of forecasts of hedge fund returns using an ordinary least squares (OLS) regression model, a nonparametric regression model, and a nonlinear nonparametric model. We backtest to assess these forecasts using three different portfolio construction processes: an “optimized” portfolio, an equally-weighted portfolio, and the Kelly criterion-based portfolio. We find that the Kelly criterion is a reasonable method for constructing a fund of hedge funds, producing better results than a basic optimization or an equally-weighted portfolio construction method. Our backtests also indicate that the nonparametric forecasts and the OLS forecasts produce similar performance at the hedge fund index level. At the individual fund level, our analysis indicates that the OLS forecasts produce higher directional accuracy than the nonparametric methods but the nonparametric methods produce more accurate forecasts than OLS. In backtests, the highest information ratio to predict hedge fund returns is obtained from a combination of the OLS regression with the Fung–Hsieh eight-factor variables as predictors using the Kelly criterion portfolio construction method. Similarly, the highest information ratio using forecasts generated from a combination of the nonparametric regression using the Fung–Hsieh eight-factor model variables is achieved using the Kelly criterion portfolio construction method. Simulations using risk-adjusted total returns indicate that the nonparametric regression model generates superior information ratios than the analogous backtest results using the OLS. However, the benefits of diversification plateau with portfolios of more than 20 hedge funds. These results generally hold with portfolio implementation lags up to 12 months.