Sovereign risk assessment and agency credit ratings

Sovereign ratings are gaining importance as more governments with greater default risk borrow in international bond markets. However, while the ratings have proved useful to governments seeking market access, the difficulty of assessing sovereign risk has led to agency disagreements and public controversy over specific rating assignments. Recognising this difficulty, the financial markets have shown some scepticism toward sovereign ratings when pricing issues.     

Large portfolio losses

This paper provide a large-deviations approximation of the tail distribution of total financial losses on a portfolio consisting of many positions. Applications include the total default losses on a bank portfolio, or the total claims against an insurer. The results may be useful in allocating exposure limits, and in allocating risk capital across different lines of business. Assuming that, for a given total loss, the distress caused by the loss is larger if the loss occurs within a smaller time period, we provide a large-deviations estimate of the likelihood that there will exist a sub-period of the future planning period during which a total loss of the critical severity occurs. Under conditions, this calculation is reduced to the calculation of the likelihood of the same sized loss over an initial time interval whose length is a property of the portfolio and the critical loss level.Received: March 2003Mathematics Subject Classification: 60F10, 91B28, 91B28JEL Classification: G21, G22, G33Amir Dembo is with the Department of Statistics, Stanford University. His research was partially supported by NSF grant #DMS-0072331. Jean-Dominique Deuschel is with the Department of Mathematics, Technische Universität, Berlin. His research was partially supported by DFG grant #663/2-3 and DFG FZT 86. Darrell Duffie is with the Graduate School of Business, Stanford University. We are extremely grateful for research assistance by Nicolae Gârleanu and Gustavo Manso, for conversations with Michael Gordy, and for comments from Michael Stutzer, Peter Carr, David Heath, and David Siegmund.     

Liquidity Pools, Risk Sharing, and Financial Contagion

This paper reevaluates the Allen–Gale (2000) analysis of interbank deposits to explain financial contagion. This paper modifies the pecking order of asset liquidation developed in Allen–Gale, which is essential in fragility analysis. Furthermore, we also provide a claim structure called liquidity pool that can both achieve risk sharing and prevent financial contagion across regions when asymmetric information about bank assets is absent. This model can partly explain why bank panics reduced substantially after the founding of the Fed and the role of IMF in regional financial crises.     

Efficient rank tests for semiparametric competing risk models

We consider a semiparametric competing risk model given by k independent survival times. The paper offers an asymptotic treatment of tests for the semiparametric null hypothesis of equality of the underlying risks. It turns out that modified rank tests are asymptotically efficient for certain semiparametric submodels, where the baseline hazard is a nuisance parameter. In addition, the asymptotic relative efficiency of the present tests is derived. A comparison of asymptotic power functions can then be used to classify various tests proposed earlier in the literature. For instance a chi-square type test is efficient for proportional hazards. Data driven tests of likelihood ratio type are proposed for cones of alternatives. We will consider certain stochastically increasing alternatives as a special example. The paper shows how the concept of local asymptotic normality of Le Cam works for hazard oriented models.     

Left-side Relatively Weak Increases in Risk and Their Comparative Statics

This paper proposes a new concept, a left-side relatively weak increase in risk (L-RWIR) order, that extends the definition of a relatively weak increase in risk (RWIR) order. We show that, for the class of linear payoffs, one can obtain an appealing comparative statics result for L-RWIR shifts imposing additional restrictions on risk preferences of a risk-averse decision maker.JEL classification: D81.revised version received October 10, 2003Acknowledgements The authors would like to thank an anonymous referee for insightful comments and useful suggestions.     

Precautionary Demand for Education, Inequality, and Technological Progress

This paper offers an explanation for the evolution of wage inequality within and between industries and education groups over the past several decades. The model is based on the disproportionate depreciation of technology-specific skills versus general skills due to technological progress, which occurs randomly across sectors. Consistent with empirical evidence, the model predicts that increasing randomness is the primary source of inequality growth within uneducated workers, whereas inequality growth within educated workers is determined more by changes in the composition and return to ability. Increasing randomness generates a precautionary demand for education, which we show empirically to be significant.     

Recovering Risky Technologies Using the Almost Ideal Demand System: An Application to U.S. Banking

We present and estimate a model that shifts the focus of modeling production from the traditional assumptions of profit maximization and cost minimization to a more general assumption of managerial utility maximization that can incorporate risk incentives into the analysis of production and recover value-maximizing technologies. We implement the model using the almost ideal demand system. In addition, we use the model to measure efficiency in a more general way that can incorporate a concern for the market value of firms assets and equity and identify value-maximizing firms. This shift in focus bridges the gap between the risk incentives literature in banking that ignores the microeconomics of production and the production literature that ignores the relationship between production decisions and risk. Our estimation of the model for a sample of U.S. commercial banks illustrates that results obtained from our generalized model can differ significantly from those obtained from the standard profit-maximization model, which ignores risk.     

抵押风险分析和抵押贷款违约损失率研究

违约损失率是BaselⅡ规定的六大风险指标之一,而抵押是BaselⅡ标准法规定的信用风险缓释工具之一,两者在巴塞尔新资本协议中有着非常关键的地位和作用.本文总结了国内外违约损失率的研究概况,在利用历史数据对我国商业银行抵押贷款的违约损失率进行实证分析后发现：（1）回收率同融资金额成反比;（2）回收率同融资折率成反比;（3）回收率呈“U”型分布.本文的分析有助于进一步探究我国商业银行抵押贷款违约损失率的特征,是量化风险暴露和计算监管资本的基础,并为我们下一步的折率研究做好了铺垫.     

国际结算和贸易融资风险的识别与控制

贸易融资较传统的流动资金贷款业务具有更大的市场适应能力.生产制造型企业贸易融资风险的主要影响因素有核心技术和装备情况、产品更新换代能力、国际品牌效应、人力成本.生产制造型企业资金流风险的主要影响因素有原材料采购与销售价格、结算方式、资产的流动性、盈利能力.贸易类企业融资风险的主要影响因素有上下游客户的稳定性、市场需求的稳定性、资金的可流动性.物流企业融资风险的主要影响因素有公司的收入及成本构成、应对市场价格变动的能力、上下游客户情况、企业的资金流.     

基于精算方法的信用风险的量化

比较了保险风险和信贷风险的基本特征后可以发现，精算模型的方法和思路可以用来描述商业银行的信用风险。可以通过定性分析和定量分析相结合的方式，推导出适用的信用风险量化管理模型。在数据整理和检验的基础上，借鉴寿险精算的生命模型思想可以建立“正常-损失”模型，进而实现对贷款损失率的解释；借鉴非寿险准备金测算的方法，可以采用链梯法测算商业银行短期贷款业务应提取的贷款坏账准备金数额。在上述方法的基础上，可以将“正常-损失”模型与链梯法结合起来，测算长期贷款的坏账准备金。