Pricing CDS spreads with Credit Valuation Adjustment using a mixture copula

Credit derivatives pricing models before Basel III ignored losses in market value stemming from higher probability of counterparty default. We propose a general credit derivatives pricing model to evaluate a Credit Default Swap (CDS) with counterparty risk, including the Credit Valuation Adjustment (CVA) in order to optimize the economic capital allocation. We work from the model proposed by Luciano (2003, Working Paper, International Center of Economic Research) and the general pricing representation established by Sorensen and Bollier (Financial Analysts Journal 1994;50(3):23–33) to provide a model close to the market practice, easy to implement and fitting with Basel III framework. We approach the dependence between counterparty risk and that of the reference entity with a technical tool: the copula, in particular, the mixture one that combines common “extreme” copulas. We study the CDS's vulnerability in extreme dependence cases. By varying Spearman's rho, the mixture copula covers a broad spectrum of dependence and ensures closed form prices. We end up with an application on real market data.     

How are Africa's emerging stock markets related to advanced markets? Evidence from copulas

The finance literature provides ample evidence that diversification benefits hinges on dependence between assets returns. A notable feature of the recent financial crisis is the extent to which assets that had hitherto moved mostly independently suddenly moved together resulting in joint losses in most advanced markets. This provides grounds to uncover the relative potential of African markets to provide diversification benefits by means of their correlation with advanced markets. Therefore, we examine the dependence structure between advanced and emerging African stock markets using copulas. Several findings are documented. First, dependence is time-varying and weak for most African markets, except South Africa. Second, we find evidence of asymmetric dependence, suggesting that stock return comovement varies in bearish and bullish markets. Third, extreme downward stock price movements in the advanced markets do not have significant spillover effects on Africa’s emerging stock markets. Our results, implying that African markets, with the exception of South Africa, are immune to risk spillover from advanced markets, improves the extant literature and have implications for portfolio diversification and risk management.     

Forecasting portfolio-Value-at-Risk with nonparametric lower tail dependence estimates

We propose to forecast the Value-at-Risk of bivariate portfolios using copulas which are calibrated on the basis of nonparametric sample estimates of the coefficient of lower tail dependence. We compare our proposed method to a conventional copula-GARCH model where the parameter of a Clayton copula is estimated via Canonical Maximum-Likelihood. The superiority of our proposed model is exemplified by analyzing a data sample of nine different bivariate and one nine-dimensional financial portfolio. A comparison of the out-of-sample forecasting accuracy of both models confirms that our model yields economically significantly better Value-at-Risk forecasts than the competing parametric calibration strategy.     

Exchange rate contagion in Latin America

A regular vine copula approach is implemented for testing for contagion among the exchange rates of the six largest Latin American countries. Using daily data from June 2005 through April 2012, we find evidence of contagion among the Brazilian, Chilean, Colombian and Mexican exchange rates. However, there are interesting differences in contagion during periods of large exchange rate depreciation and appreciation. Our results have important implications for the response of Latin American countries to currency crises originated abroad.     

基于时变Copula的我国股票市场联动性研究

通过运用Copula技术,构建4种Copula-GARCH模型,讨论金融市场的相关模式问题得出的结论是Joe-ClaytonCopula比正态Copula好,动态模型比静态模型要好。表明沪港股市确实存在非对称的相关变化规律。同时表明沪、港股票市场股市相关程度较小,两个市场联动性较弱,上海股市的波动具有相对的独立性,通过组合上海股市和香港股市的方式可以较好的降低投资风险。     

Contracts with endogenous information

I study covert information acquisition and reporting in a principal agent problem allowing for general technologies of information acquisition. When posteriors satisfy two dimensional versions of the standard First Order Stochastic Dominance and Concavity/Convexity of the Distribution Function conditions, a first-order approach is justified. Under the same conditions, informativeness and riskiness of reports are equivalent. High powered contracts, that make the agent's informational rents more risky, are used to increase incentives for information acquisition, insensitive contracts are used to reduce incentives for information gathering. The value of information to the agent is always positive. The value of information to the principal is ambiguous.     

基于Copula的道指与恒指的尾部相关性分析

Copula函数能有效地刻画随机变量间的非对称性和尾部相关性。在研究当道琼斯工业指数与恒生指数的相关性时,采用非参数核密度估计拟合边缘分布。并应用Kol mogorov-Smirrnov检验三种Archi medean Copula函数。研究发现参数值θ=0.2221的Clayton Copula可以用于描述下尾相关性,而θ=1.1105的Gumbel Copula可用于描述上尾相关性。     

基于Copula函数我国林业经济发展与气候之间的关系研究

我国林业经济在国民经济发展中有着重要的地位,森林与气候之间也有着密切的关系。通过历史数据基于Copula函数模型验证林业经济发展与气温、降水量、湿度与日照数等气候因素之间的相关关系,林业生产总值与气温正相关,与湿度、日照数负相关。当我们认识到林业经济总产值与气温、降水量、湿度、日照数之间的相依关系和相依结构,就可以采取相应的措施。这将会对制定宏观经济发展规划与森林资源开发战略,具有一定的指导与实践意义。     

基于经济资本的我国保险公司投资风险限额配置研究

投资风险限额管理是保险公司对投资风险进行管理的重要手段,是保险公司建立有效风险管理体系不可或缺的组成部分。保险公司投资风险限额管理主要包括投资风险限额配置、风险限额监控和风险限额动态调整三个环节,其中风险限额配置是整个风险限额管理流程的基础。运用GARCH模型和GJR模型,并结合Copula理论,探讨了投资风险限额配置的方法,通过实证分析证实投资组合之间存在分散化效应,各投资风险限额之和大于总风险限额,并得出投资风险限额优化配置模型调整资产配置,可以显著提高保险公司投资绩效。