10 天 99% VaR Ten-day 专题 Finance / 金融 难度 L4 来源 QuantQuestion 收藏 标记掌握 个人笔记 题目详情 金融数学题:10 天 99% VaR:时间与置信度缩放。 英文原题 What is the ten- day 99%99\%99% VaR of a portfolio with a five- day 98%98\%98% VaR of $101010 million? 解析 正态近似下 VaR 近似满足 VaR(N,C)∝zCN.\operatorname{VaR}(N,C)\propto z_C\sqrt{N}.VaR(N,C)∝zCN. 因此 VaR(10,99%)≈VaR(5,98%)⋅z0.9910z0.985.\boxed{\operatorname{VaR}(10,99\%)\approx \operatorname{VaR}(5,98\%)\cdot \frac{z_{0.99}\sqrt{10}}{z_{0.98}\sqrt{5}}}.VaR(10,99%)≈VaR(5,98%)⋅z0.985z0.9910. 代入 VaR(5,98%)=10M\operatorname{VaR}(5,98\%)=10\text{M}VaR(5,98%)=10M,z0.99≈2.3263z_{0.99}\approx 2.3263z0.99≈2.3263,z0.98≈2.0537z_{0.98}\approx 2.0537z0.98≈2.0537,得到约 16.0M16.0\text{M}16.0M。 英文解析 VaR(N,C)∝zCN.\operatorname{VaR}(N,C)\propto z_C\sqrt{N}.VaR(N,C)∝zCN. VaR(10,99%)≈VaR(5,98%)⋅z0.9910z0.985.\boxed{\operatorname{VaR}(10,99\%)\approx \operatorname{VaR}(5,98\%)\cdot \frac{z_{0.99}\sqrt{10}}{z_{0.98}\sqrt{5}}}.VaR(10,99%)≈VaR(5,98%)⋅z0.985z0.9910.