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arXiv 2209.07092q-fin.RMq-fin.ST
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尾部风险的度量

Measuring Tail Risks

Kan Chen, Tuoyuan Cheng

AI总结:

针对现有尾部风险度量需指定置信水平的问题,提出基于风险事件最可能最大规模(MPMR)的度量方法,推导其分布特性与尾部指数估计方式,可用于金融与自然灾害风险评估。

摘要:

风险价值(VaR)和期望短缺(ES)是金融监管与风险管理中常用的、基于高分位数的风险度量指标。本文提出了一种基于一段时间内可能发生的风险事件最可能最大规模(MPMR)的尾部风险度量方法,MPMR凸显了尾部风险对风险管理时间框架的依赖性。与VaR和ES不同,MPMR无需指定置信水平。我们针对若干知名分布解析推导了该风险度量的表达式。特别地,当风险事件规模服从幂律分布或Pareto分布时,我们证明MPMR同样以幂律形式随观测数量$n$(等价于时间区间长度)缩放,即$\text{MPMR}(n) \propto n^η$,其中$η$为缩放指数。这种尺度不变性使得我们可以通过外推更可靠的短期风险估计值,对长期风险进行合理估算。该缩放关系还可用于推导规模分布尾部指数(TI)$ξ$的稳健低偏差估计量,即$ξ= 1/η$。我们展示了该风险度量方法在描述金融市场尾部风险以及自然灾害(地震、海啸和极端降雨)相关风险方面的应用。

英文摘要:

Value at risk (VaR) and expected shortfall (ES) are common high quantile-based risk measures adopted in financial regulations and risk management. In this paper, we propose a tail risk measure based on the most probable maximum size of risk events (MPMR) that can occur over a length of time. MPMR underscores the dependence of the tail risk on the risk management time frame. Unlike VaR and ES, MPMR does not require specifying a confidence level. We derive the risk measure analytically for several well-known distributions. In particular, for the case where the size of the risk event follows a power law or Pareto distribution, we show that MPMR also scales with the number of observations $n$ (or equivalently the length of the time interval) by a power law, $\text{MPMR}(n) \propto n^η$, where $η$ is the scaling exponent. The scale invariance allows for reasonable estimations of long-term risks based on the extrapolation of more reliable estimations of short-term risks. The scaling relationship also gives rise to a robust and low-bias estimator of the tail index (TI) $ξ$ of the size distribution, $ξ= 1/η$. We demonstrate the use of this risk measure for describing the tail risks in financial markets as well as the risks associated with natural hazards (earthquakes, tsunamis, and excessive rainfall).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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