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Shuangshuang · 2024年08月03日

没看懂

NO.PZ2024042601000097

问题如下:

Sam prices a put option on an asset with the Black-Scholes-Merton option pricing model and calculates a model premium of $25. This $25 also coincidentally equals the present-valued expected exposure faced by Sam with respect to the short option position. Sam estimates the probability of counterparty default by the option writer to be 10% with loss given default of 40%, such that the expected loss = $25 EE (writer) × 10% PD × 40% LGD = $1. He concludes that the CVA-adjusted (net of counterparty risk) option price is $24. His colleague Jane observes that this calculation assumes no wrong-way risk. But there is a high, positive correlation between underlying asset price and the credit quality of the option writer counterparty: both the counterparty and underlying share a sector that reacts to the same common factors such that adverse economic regimes depress sector asset prices while lowering sector credit quality (and increasing credit spreads). Is Jane correct that the CVA-adjusted option value deserves further adjustment?

选项:

A.

As the correlation is positive, this is instead right-way risk; but the true CVA-adjusted value remains $24 as there is no adjustment for right-way risk

B.

As the correlation is positive, this is instead right-way risk; therefore, the true CVA-adjusted value will be higher than $24

C.

Jane is correct that this is wrong-way risk; therefore, true CVA-adjusted value will be lower than $24

D.

Jane is correct that this is wrong-way risk but expected loss is not impacted by correlation, so Sam correctly has the CVA-adjusted value at $24

解释:

We refer to wrong-way risk as the adverse (negative) correlation between the exposure to the counterparty and its credit quality. Alternatively, it can be stated as the positive correlation between exposure and credit spread.

But there is a high, positive correlation between underlying asset price and the credit quality of the option writer counterparty

positive correlation难道不是信用质量和资产价格正相关吗?

对手方信用质量下降,价格下降,put option 赚钱,敞口变大,所以是wrong way。

可是题目里不是说假设没有 wrong way么,没看懂为啥jane是对的呢

2 个答案
已采纳答案

pzqa27 · 2024年08月05日

嗨,从没放弃的小努力你好:


题目说的“ Jane observes that this calculation assumes no wrong-way risk. ”,不是我们判断出来的,是题目明确告诉我们之前的结论是没有考虑到wrong-way risk,现在需要对之前的结论进行调整,问我们这种调整对不对,这个是对的,因为对手方信用质量下降,价格下降,put option 赚钱,敞口变大,所以存在wrong way。因此我们是要对原来的CVA进行调整的。

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就算太阳没有迎着我们而来,我们正在朝着它而去,加油!

pzqa27 · 2024年08月05日

嗨,爱思考的PZer你好:


题目说了“ Jane observes that this calculation assumes no wrong-way risk. ”也就是说Jane这个人认为我们之前的观测是基于没有wrong way risk的,那么现在确实有wrong way risk,所以jane 认为需要调整是没有问题的。

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就算太阳没有迎着我们而来,我们正在朝着它而去,加油!

Shuangshuang · 2024年08月05日

怎么判断出之前的公式没有wrongway的啊

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