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莫等闲2023 · 2021年07月09日

stock price=strike price,当做short ATM Call 来看,认为delta 是 -0.5,为什么不对?

NO.PZ2020021205000065

问题如下:

a short position on 100,000 call options on a stock with a market price and strike price of USD 40 when the risk-free rate is 5%, the volatility is 22%, and the time to maturity is nine months what trade should be done to create a delta-neutral position? (Assume that the trader has no other positions dependent on the stock price.) If the stock price increases to USD 41 within a very short period, what further trade is necessary?

选项:

解释:

The trader should buy 61,500 shares of the stock to create a delta-neutral position. If the stock price then moves up to USD 41:

d1=ln(41/40)+(0.05+0.222/2)×0.750.220.75=0.4217d1=\frac{\ln(41/40)+(0.05+0.22^2/2)\times0.75}{0.22\sqrt{0.75}}=0.4217

and N(d1 ) = 0.663. The delta of the option position is -66,300 and a further 4,800 shares should be purchased.

因为题目中stock price=strike price,当做short ATM Call 来看,认为delta 是 -0.5。

请问这种想法为什么不对?为什么何用BSM计算的d1公式结果不一样?谢谢。

1 个答案
已采纳答案

品职答疑小助手雍 · 2021年07月09日

嗨,努力学习的PZer你好:


我们说的ATM的delta是0.5,deep ITM的是1,OTM的是0都是很粗略的大致估计,当然跟BSM算的结果不一样。

做题时候需要根据题目给的条件去判断如何处理的~

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