VaR RAROC与投资组合问题探讨

以VaR为风险度量工具、以RAROC作为目标函数的投资决策模型。利用资产回报分布的偏度和峰度 ,对VaR进行调整 ,使它可以应用于非正态分布时的资产组合风险价值估计 ,而不增加计算的复杂性 ;同时又对RARAOC作了修正 ,使之克服了RAROC的缺点。应用此模型 ,使投资组合经理在受到内外部施加VaR限额约束时 ,在上级以RAROC作为投资业绩评估工具的情形下 ,可以有效地实现资产组合的优化配置。     

基于CVaR的投资组合优化模型研究

风险价值(VaR)是近年来国际金融机构所倡导的测度和控制金融风险的国际主流技术,但是它在投资组合损益服从非正态分布的情形时,不满足一致性风险度量,出现尾部损失测量的非充分性。为了使具有一致性的条件风险值度量(CVaR)克服VaR的不足,构建基于CVaR约束的投资组合优化模型,该模型虑及了投资组合资产的交易成本、交易限制、资金约束和投资者的风险承受度,为制定合理的最优投资组合提供了一种新的思路。     

基矛CVaR的投资组合优化模型研究

风险价值（VaR）是近年来国际金融机构所倡导的测度和控制金融风险的国际主流技术，但是它在投资组合损益服从非正态分布的情形时，不满足一致性风险度量，出现尾部损失测量的非充分性。为了使具有一致性的条件风险值度量（CVaR）克服VaR的不足，构建基于CVaR约束的投资组合优化模型，该模型虑及了投资组合资产的交易成本、交易限制、资金约束和投资者的风险承受度，为制定合理的最优投资组合提供了一种新的思路。     

基于VaR模型的股票组合投资风险管理研究

本文探讨了将GARCH模型与方差-协方差方法相结合的VaR风险计量方法,并用VaR风险替代Markiwitz组合投资模型中的方差风险,通过求解非线性规划问题,得到最小化股票投资组合VaR风险的最优投资策略。     

均值-CVaR模型在正态条件下风险资产组合的研究

条件风险值(CVaR)是指金融资产或其组合的损失额超过VaR的条件均值,它克服了VaR的非一致性,不满足凸性等局限性。给出了在风险证券的预期回报率服从正态分布下的均值-CVaR模型及最小均值-CVaR风险资产组合有解的条件,并在该条件满足下的最小均值-CVaR组合的投资比例向量和最小值。     

基子VaR模型的股票组合投资风险管理研究

本文探讨了将GARCH模型与方差-协方差方法相结合的VaR风险计量方法,并用VaR风险替代Markiwitz组合投资模型中的方差风险,通过求解非线性规划问题,得到最小化股票投资组合VaR风险的最优投资策略.     

基于偏度的多期证券投资组合模型研究

在考虑资产收益率分布中正的偏度水平前提下,以风险价值VaR为约束条件,并引入非线性交易费用、税收等市场摩擦因素,建立以累积偏度最大为目标函数的多期投资组合优化模型,用罚函数法和PSO算法结合求解此模型,并给出实证分析。考虑到在买卖资产风险时交易费用等对投资收益的影响,投资者应该在每一期都对其资产组合进行调整分析,确保在每一期的开始都建立起符合需要的最优资产组合,这对投资者的连续投资行为具有一定的指导意义。     

基于Copula-EVT方法的组合风险度量分析

资产组合风险模型要解决两个问题,一是资产收益或损失分布存在肥尾现象,传统的正态分布假设导致风险值(VaR)的低估;二是资产损失相依结构的描述.本文采用GPD分布来拟合损失分布的尾部和经验分布拟合损失分布的中间部分,运用Copula函数来刻画资产损失的相依结构,能较好地解决这两个问题.在刻画和估计资产的联合损失分布函数的基础上,本文分别计算了VaR和资产组合损失(ES).并发现改进后的VaR和ES能更好地反映资产组合的风险状况.     

基于VaR的证券组合优化方法

基于VaR的最优投资决策问题,给出了在VaR约束下的投资组合优化模型。该模型在马柯维茨均值-方差模型的基础上,加入了VaR约束,保证了其风险度量手段与我国金融机构现有投资选择方法在技术上的一致性。     

公司债券和股票的收益率相关性实证研究

本文首先对股票风险以及股票风险管理理论的发展脉络进行了梳理与介绍。之后本文对VaR方法进行了详细的介绍,包括其来源、定义、特点和不足之处。接着对VaR的三种主要计算方法进行了介绍,并对每种方法的优缺点进行了分析。最后提出了基于VaR的每单位风险收益,用单位风险收益来进行股票组合管理,然后使用模拟投资组合对此进行实证分析,并对分析结果进行了总结与展望。     

基于极值理论的沪深股市VaR和CVaR分析

将VaR和CVaR结合起来能全面描述金融时间序列与尾部相关的风险。考虑沪深股指收益序列胖尾特性,极值理论方法能够对沪深股市VaR和CVaR进行较好估计,运用基于Boot strap和极大似然估计方法解决极值理论数据不足的缺陷,从而给出对VaR和CVaR的点估计和区间估计。     

Risk management with weighted VaR

This article studies the optimal portfolio selection of expected utility‐maximizing investors who must also manage their market‐risk exposures. The risk is measured by a so‐called weighted value‐at‐risk (WVaR) risk measure, which is a generalization of both value‐at‐risk (VaR) and expected shortfall (ES). The feasibility, well‐posedness, and existence of the optimal solution are examined. We obtain the optimal solution (when it exists) and show how risk measures change asset allocation patterns. In particular, we characterize three classes of risk measures: the first class will lead to models that do not admit an optimal solution, the second class can give rise to endogenous portfolio insurance, and the third class, which includes VaR and ES, two popular regulatory risk measures, will allow economic agents to engage in “regulatory capital arbitrage,” incurring larger losses when losses occur.     

INVESTING WITH LIQUID AND ILLIQUID ASSETS

We find optimal trading policies for long‐term investors with constant relative risk aversion and constant investment opportunities, which include one safe asset, liquid risky assets, and an illiquid risky asset trading with proportional costs. Access to liquid assets creates a diversification motive, which reduces illiquid trading, and a hedging motive, which both reduces illiquid trading and increases liquid trading. A further tempering effect depresses the liquid asset's weight when the illiquid asset's weight is close to ideal, to keep it near that level by reducing its volatility. Multiple liquid assets lead to portfolio separation in four funds: the safe asset, the myopic portfolio, the illiquid asset, and its hedging portfolio.     

Liability driven investment with alternative assets: Evidence from Brazil

We study the portfolio choice problem for an asset-liability investor who invests in stocks, equity mutual funds, government bonds, short term interest, hedge funds, listed real estate, and commodities futures available in Brazil. Inflation and real interest play as important risk sources. We estimate the asset classes and liabilities time-varying conditional covariance structure using an asymmetric multivariate dynamic conditional correlation GARCH model and compare the asset-liability portfolio's global minimum variance allocation with Brazilian pension funds' market portfolio. The conditional covariance structure provides insights about the complex dynamic relationships between the asset classes and liabilities. We find that some (though not all) Brazilian alternative assets render strong diversification and liabilities hedging benefits for asset-liability investors. There are significant strategic asset allocation differences between the market portfolio and the liability driven portfolio as given by our model. We, therefore, question the Brazilian pension funds' allocation.     

我国开放式基金业绩持续性的实证检验

本文运用绩效二分法和横截面回归方法对我国开放式基金的业绩持续性进行了检验。实证结果发现,我国开放式基金从总体上看业绩持续性不强,业绩持续性只是在短期内出现,基金经理不能连续战胜市场。此外,开放式基金在短期内还有显著的业绩反转现象产生,说明很难根据基金过去的收益来判断其未来的业绩。     

VaR在投资组合应用中存在的缺陷与CVaR模型

VaR在投资组合应用中存在的两个缺陷:一是不满足一致性公理,二是尾部损失测量的非充分性,这些缺陷可能导致组合优化上的错误.当且仅当组合回报服从正态分布时,VaR才能应用于组合优化,这极大地限制了VaR在投资组合管理中的适用范围.本文最后介绍了CVaR模对VaR模型的改进及其在投资组合优化中的应用.     

保险资金投资管理中的风险分散问题研究

组合投资是利用投资组合内各个风险资产之间的相关性来分散风险的,而均值—方差投资组合模型采用的相关性度量—相关系数无法准确地度量风险资产之间的相关性,这必将对组合投资的风险分散效果产生不利影响。本文提出,用理论性质更好的相关性度量来度量风险资产之间的相关性,并建立基于Kendallτ的投资组合模型。通过实证研究发现,在保险资金投资管理中,采用基于Kendallτ的投资组合模型能够取得比均值—方差投资组合模型更好的风险分散效果。     

Dynamic Optimal Pension Fund Portfolios when Risk Preferences Are Heterogeneous among Pension Participants

In this paper, we consider the problem of an optimal pension fund portfolio given the heterogeneous risk preferences of pension fund participants. The relative risk aversion of a pension fund tends to be a decreasing function of the level of aggregate wealth. We find that the dynamic optimal portfolio is simply characterized as the weighted sum of the optimal portfolio for each participant. Our model helps successfully establish the microfoundation of asset liability management models. A numerical example using recent Japanese data indicates the significant total welfare losses of adopting a suboptimal portfolio strategy and an inefficient risk‐sharing rule.     

RISK HORIZON AND REBALANCING HORIZON IN PORTFOLIO RISK MEASUREMENT

This paper analyzes portfolio risk and volatility in the presence of constraints on portfolio rebalancing frequency. This investigation is motivated by the incremental risk charge (IRC) introduced by the Basel Committee on Banking Supervision. In contrast to the standard market risk measure based on a 10‐day value‐at‐risk calculated at 99% confidence, the IRC considers more extreme losses and is measured over a 1‐year horizon. More importantly, whereas 10‐day VaR is ordinarily calculated with a portfolio’s holdings held fixed, the IRC assumes a portfolio is managed dynamically to a target level of risk, with constraints on rebalancing frequency. The IRC uses discrete rebalancing intervals (e.g., monthly or quarterly) as a rough measure of potential illiquidity in underlying assets. We analyze the effect of these rebalancing intervals on the portfolio’s profit and loss distribution over a risk‐measurement horizon. We derive limiting results, as the rebalancing frequency increases, for the difference between discretely and continuously rebalanced portfolios; we use these to approximate the loss distribution for the discretely rebalanced portfolio relative to the continuously rebalanced portfolio. Our analysis leads to explicit measures of the impact of discrete rebalancing under a simple model of asset dynamics.