《Asset correlation estimation for inhomogeneous exposure pools》
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作者:
Christoph Wunderer
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最新提交年份:
2019
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英文摘要:
A possible data source for the estimation of asset correlations is default time series. This study investigates the systematic error that is made if the exposure pool underlying a default time series is assumed to be homogeneous when in reality it is not. We find that the asset correlation will always be underestimated if homogeneity with respect to the probability of default (PD) is wrongly assumed, and the error is the larger the more spread out the PD is within the exposure pool. If the exposure pool is inhomogeneous with respect to the asset correlation itself then the error may be going in both directions, but for most PD- and asset correlation ranges relevant in practice the asset correlation is systematically underestimated. Both effects stack up and the error tends to become even larger if in addition a negative correlation between asset correlation and PD is assumed, which is plausible in many circumstances and consistent with the Basel RWA formula. It is argued that the generic inhomogeneity effect described is one of the reasons why asset correlations measured from default data tend to be lower than asset correlations derived from asset value data.
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中文摘要:
估计资产相关性的一个可能数据源是默认时间序列。本研究调查了如果假设默认时间序列下的风险敞口池是同质的,而实际上不是同质的,则会产生的系统误差。我们发现,如果错误地假设违约概率(PD)的同质性,那么资产相关性总是会被低估,并且误差越大,PD在风险池中的分布就越广。如果风险敞口池就资产相关性本身而言是不均匀的,那么误差可能在两个方向上都存在,但对于大多数实际相关的PD和资产相关性范围,资产相关性被系统地低估了。此外,如果假设资产相关性与PD之间存在负相关性,则这两种效应叠加在一起,误差往往会变得更大,这在许多情况下都是合理的,并且与巴塞尔RWA公式一致。有人认为,所描述的一般不均匀性效应是从违约数据测量的资产相关性往往低于从资产价值数据得出的资产相关性的原因之一。
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分类信息:
一级分类:Quantitative Finance 数量金融学
二级分类:Risk Management 风险管理
分类描述:Measurement and management of financial risks in trading, banking, insurance, corporate and other applications
衡量和管理贸易、银行、保险、企业和其他应用中的金融风险
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