对我国开放式基金风险的实证研究——基于GARCH模型的VaR方法

从我国开放式基金收益率序列的分布、波动性和杠杆效应三方面考虑,在正态分布、t分布和GED分布的假设下,-建立了估计基金风险的VaR—GARCH、VaR—EGARCH模型,选择合适的模型对各只基金及不同类型基金的VaR值进行估计,并应用Kupiec方法对VaR模型的准确性进行了返回检验。结果显示,基于GED分布的GARCH模型计算的VaR值比基于t分布的GARCH模型计算的VaR值更真实地反映了基金的风险,不同投资类型和投资风格的基金的风险也不尽相同。     

基于GARCH模型的证券投资基金VaR计算与实证研究

基于统计技术的度量金融市场风险值(Value at Risk,VaR)已成为测量市场风险的新标准和新方法。鉴此,如何高效、准确地进行VaR的计算将是问题所在。基于GARCH模型,讨论了对数收益率时间序列在正态、学生t和广义误差(GED)三种不同分布下的VaR计算方法,对样本基金的市场风险进行估计,并通过返回检验来检验模型的准确性。研究结果表明,基于GED分布的GARCH模型计算的VaR值最能真实地反映基金风险。     

基于GARCH模型的VaR方法的实证分析——以开放式基金为研究对象

从我国开放式基金收益率序列的分布、波动性和杠杆效应三方面考虑,在正态分布、t分布和GED分布的假设下,建立了估计基金风险的VaR-GARCH、VaR-EGAKCH模型.选择合适的模型对各只基金及不同类型基金的VaR值进行估计,最好根据结果得出相应的结论.     

不同分布下中国股市的VaR度量——基于ARFIMA-FIGACH模型

基于正态分布、学生-t分布、GED分布和Skewed-t分布四种不同分布,采用ARFIMA-FIGARCH模型对深圳股市收益率的风险值进行了动态建模。通过模型实证参数估计,发现深圳股市收益率序列存在双长记忆性特征;通过模型预测的VaR值的DQ和LR测试,发现在Skewed-t分布下,ARFIMA-FIGARCH模型能更有效地捕捉深圳股市收益率序列的特性,能够较好地反映金融收益率的实际风险。     

上证综指收益波动性及VaR度量研究

基于对上证综指日回报序列分布分别作正态分布、t分布和广义误差分布(GED)的假设基础上,采用(E)GARCH模型和方差-协方差法,度量了上海股票市场的潜在风险和波动性。在验证了三个模型对VaR估计的有效性之后,得出AR(1)-EGARCH(1,1)-M-GED模型对上海股票市场的拟合最优,并得出了有效的VaR估值。     

基于GJR—ALaplace方法的开放式基金风险研究

根据我国开放式基金收益率序列的尖峰、厚尾、有偏和波动时变的特征,引入非对gg,Laplace分布对收益率序列进行刻画和拟合。构建度量基金风险的动态GJR—Asymmetric～Laplace模型,在非对称Laplace分布、Laplace分布和正态分布三种分布假设下测算VaR,并做返回检验。选取12只开放式基金在2007．01．04～2009．12．31期间的日累计净值数据做实证研究。实证表明：除了基金大成债券外,其余11只基金显著通过假设,符合非对称Laplace分布,相rELaplace分布和正态分布来说,非对称Laplace分布能更好地拟合基金收益率序列。正态分布假设下风险度量值通过检验的基金数显著少于Laplace分布假设,而Laplace分布下通过检验的基金数亦少于非对称Laplace分布,可知非对称hplace分布假设下得出的基金动态风险值更为有效。     

我国商业银行市场利率风险的VaR度量实证研究

运用GARCH族模型和分位数回归的方法对我国商业银行利率风险进行VaR度量,从而测算我国商业银行的利率风险,运用上海银行间同业拆借市场（Shibor）的隔夜拆借利率数据进行研究。通过GARCH族模型的选取可以得出正态分布和T分布并不适合我国商业银行间同业拆借市场,本文选取广义误差分布（GED）对数据进行GARCH建模并测算其VaR,同时本文运用了分位数回归的方法对VaR进行测算,从结果证明分位数回归方法更适合VaR的度量。     

基于稳定分布条件的GARCH模型研究

本文应用GARCH模型对1995～2008年的沪深A股指数收益率序列进行分析,对正态分布、学生t分布、广义误差分布以及稳定分布下的GARCH模型进行对比研究,发现基于极大似然准则和AIC信息准则下,新信息服从稳定分布的GARCH模型优于其他模型。     

基于GARCH-VaR模型的股票市场风险度量与预测分析——以新能源行业为例

一个有效的风险测度模型必须能够有效刻画金融市场的典型事实,本文将GARCH模型与VaR方法相结合,以新能源行业股票收益率为对象,比较研究了残差不同分布假定下股票收益率VaR值的精确程度,并做了向前一步的VaR失败率回测检测,结果表明残差正态分布下的GARCH-M(1,1)模型很好地刻画了新能源行业股票市场的风险特征,为预测风险提供了较好的方法.     

基于CVaR的我国银行间债券回购市场利率风险度量研究

在银行间债券回购市场利率基本特征分析基础上,利用我国银行间债券回购开始日1997年6月15日至2008年4月20日全部质押式回购每周加权平均利率进行实证研究,建立了基于ARMA-GARCH模型族的利率风险CVaR测度模型。结果表明我国银行间债券回购市场中存在杠杆效应;回购利率分布对CVaR计算结果影响较大,GED分布较正态分布和t分布能更好刻画我国银行间回购利率序列的分布状况。EGARCH模型计算得到的CVaR值要优于GARCH和TARCH模型得到的结果。     

质押式回购利率的风险度量研究——基于ARMA-GARCH模型的实证检验

文章对2002年1月4日至2009年3月31日我国银行间质押式回购市场进行实证研究,结果表明:(1)t-分布和g-分布下的模型能更好地捕捉回购利率序列的尖峰厚尾性;(2)回购利率波动具有显著的非对称性,利率上升时的波动更大;(3)ARMA-PARCH-M模型是估计回购利率VaR值的理想模型,t-分布下的模型适合多头头寸VaR值的预测,而g-分布下的模型适合空头头寸VaR值的预测.这说明我国回购市场的利率风险较高.     

Markets liquidity risk under extremal dependence: Analysis with VaRs methods

Value-at-Risk (VaR) is a widely used tool for assessing financial market risk. In practice, the estimation of liquidity extreme risk by VaR generally uses models assuming independence of bid–ask spreads. However, bid–ask spreads tend to occur in clusters with time dependency, particularly during crisis period. Our paper attempts to fill this gap by studying the impact of negligence of dependency in liquidity extreme risk assessment of Tunisian stock market. The main methods which take into account returns dependency to assess market risk is Time series–Extreme Value Theory combination. Therefore we compare VaRs estimated under independency (Variance–Covariance Approach, Historical Simulation and the VaR adjusted to extreme values) relatively to the VaR when dependence is considered. The efficiency of those methods was tested and compared using the backtesting tests. The results confirm the adequacy of the recent extensions of liquidity risk in the VaR estimation. Therefore, we prove a performance improvement of VaR estimates under the assumption of dependency across a significant reduction of the estimation error, particularly with AR (1)-GARCH (1,1)-GPD model.     

Information acquisition and mutual funds

We study the formation of mutual funds by generalizing the standard competitive noisy rational expectations framework. In our model, informed agents set up mutual funds as a means of selling their private information to uninformed agents. We study the case of imperfect competition among fund managers, where uninformed agents invest simultaneously in multiple mutual funds. The size of the assets under management in the mutual fund industry is determined by endogenizing the agents' information acquisition decisions. Our model yields novel predictions on the informativeness of price, the optimal fees of mutual funds, and the equilibrium risk premium. In particular, we show that a sufficiently competitive mutual fund sector yields more informative prices and a lower equity risk premium.     

Long-Memory,Asymmetry and Fat-Tailed GARCH Models in Value-at-Risk Estimation: Empirical Evidence from the Global Real Estate Markets

In this paper, we address the question of whether long memory, asymmetry, and fat-tails in global real estate markets volatility matter when forecasting the two most popular measures of risk in financial markets, namely Value-at-risk (VaR) and Expected Shortfall (ESF), for both short and long trading positions. The computations of both VaR and ESF are conducted with three long memory GARCH-class models including the Fractionally Integrated GARCH (FIGARCH), Hyperbolic GARCH (HYGARCH), and Fractionally Integrated Asymmetric Power ARCH (FIAPARCH). These models are estimated under three alternative innovation’s distributions: normal, Student, and skewed Student. To test the efficacy of the forecast, we employ various backtesting methodologies. Our empirical findings show that considering for long memory, fat-tails, and asymmetry performs better in predicting a one-day-ahead VaR and ESF for both short and long trading positions. In particular, the forecasting ability analysis points out that the FIAPARCH model under skewed Student distribution turns out to improve substantially the VaR and ESF forecasts. These results may have several potential implications for the market participants, financial institutions, and the government.

     

A novel nonlinear value-at-risk method for modeling risk of option portfolio with multivariate mixture of normal distributions

This paper proposes a novel nonlinear model for calculating Value-at-Risk (VaR) when the market risk factors of an option portfolio are heavy-tailed. A multivariate mixture of normal distributions is used to depict the heavy-tailed market risk factors and accordingly a closed form expression for the moment generating function that can reflect the change in option portfolio value can be derived. Moreover, in order to make use of the correlation between the characteristic function and the moment generating function, Fourier-Inversion method and adaptive Simpson rule with iterative algorithm of numerical integration into the nonlinear VaR model for option portfolio are applied for calculation of VaR values of option portfolio. VaR values of option portfolio obtained from different methods are compared. Numerical results of Fourier-Inversion method and Monte Carlo simulation method show that high accuracy VaR values can be obtained when risk factors have multivariate mixture of normal distributions than when they have normal distributions. Moreover, VaR values obtained by using the Fourier-Inversion method are not obviously different from VaR values obtained by using Monte Carlo simulation when market risk factors have normal distributions or multivariate mixture of normal distributions. However, the speed of computation is obviously faster when using Fourier-Inversion method, than when using Monte Carlo simulation method. Besides, Cornish Fisher method is faster and simpler than Monte Carlo simulation method or Fourier-Inversion method. However, this method does not offer high accuracy and cannot be used to calculate VaR values of option portfolio when market risk factors have heavy-tailed distributions.     

中国股票市场ES和VaR的实证比较分析

以我国股票收益率为研究对象,分别在正态分布和非正态稳定分布条件下对ES和VaR的凸性、次可加性和有效性进行了实证比较分析,发现:在非正态稳定分布条件下VaR不满足凸性和次可加性,ES满足凸性和次可加性,在正态分布条件下VaR和ES都满足凸性和次可加性;在两种分布条件下ES的有效性都高于VaR的有效性,而在非正态稳定分布条件下ES的优势更加明显。由于本文的收益率分布拟合检验表明我国的股票收益率服从非正态稳定分布,所以在我国股票市场上ES是比VaR更好的风险度量。     

Risk assessment of oil price from static and dynamic modelling approaches

The price gap between West Texas Intermediate (WTI) and Brent crude oil markets has been completely changed in the past several years. The price of WTI was always a little larger than that of Brent for a long time. However, the price of WTI has been surpassed by that of Brent since 2011. The new market circumstances and volatility of oil price require a comprehensive re-estimation of risk. Therefore, this study aims to explore an integrated approach to assess the price risk in the two crude oil markets through the value at risk (VaR) model. The VaR is estimated by the extreme value theory (EVT) and GARCH model on the basis of generalized error distribution (GED). The results show that EVT is a powerful approach to capture the risk in the oil markets. On the contrary, the traditional variance–covariance (VC) and Monte Carlo (MC) approaches tend to overestimate risk when the confidence level is 95%, but underestimate risk at the confidence level of 99%. The VaR of WTI returns is larger than that of Brent returns at identical confidence levels. Moreover, the GED-GARCH model can estimate the downside dynamic VaR accurately for WTI and Brent oil returns.     

标准仓单质押组合的价格风险——基于中国农产品期货规范市场的实证研究

利用基于Copula函数的AR(p)-GARCH(p,q)模型计算的VaR能够对农产品标准仓单的价格风险进行准确度量。对大连商品交易所的典型期货交易品种——黄大豆一号、豆油、豆粕的期货合约日结算价进行了实证研究。研究结果显示:从对价格风险预测的盯市频率来看,时变VaR优于静态VaR,因此重视农产品价格风险的频次预测应替代传统风险判断的单次监测;从对风险因子间相依性结构的刻画来看,基于t-Copula函数计算的VaR优于基于正态Copula函数计算的VaR,因此质押物价格波动间的相关系数是度量组合风险时必须考虑的重要变量。