The hedge ratio, h, must be:
spi + dh =spd + 0h
h = –2
The cash flows one year from today are:
Two short options are worth
The present value of the portfolio is:
Today the total portfolio cost = $sp – 2C = $pv
Therefore the call value is $cva
Using the risk-neutral method and first solving for the probability of an up move:
The expected cash flow from a call option in one year is:
Expected cash flow = p(d) + (1 – p)(0) = $ecf