原版书后习题，关于option的 option

freyayi

16. An investor writes a call option priced at $3 with an exercise price of $100 on a stock that he owns. The investor paid $85 for the stock. If at expiration of the call option the stock price has risen to $110, the profit for the investor’s position would be closest to:

A. $3.

B. $12.

C. $18.

为什么用100-85+3，而不是用110-85+3？？？？

李斯克老师

因为投资者short call at X=100。手里有一个股票购买成本85，当股票涨到110元的时候，long call会执行权力，以100元买这只股票，所以short call必须以100把这只股票卖掉，因此受益是100-85+3

freyayi

多谢，多谢