Use the Black-Scholes formula to price options with time to expiration 6 months, on a stock with price $80 and volatility 20% per year. The annualized continuously compounded interest rate is 3%. You may use the following data on the CDF of the standard normal distribution:
d -0.623 -0.393 -0.252 -0.109 0.057 0.298 0.409 0.581
N(d) 0.267 0.347 0.401 0.457 0.523 0.617 0.659 0.719
a) Show that a call with exercise price $85 has a premium of $2.985.
b) Use the put-call parity to compute the premium of a put with the same exercise price.
c) If you sell the call in a), how many shares should you buy to hedge your price risk from the call? (Hint: Compute the hedge ratio of the call.)
d) Compute again the number of shares in c) if the only change is an increase of the stock price to $90. Explain the change in the hedge ratio.
e) If the stock volatility was 30% instead of 20%, would the call premium in a) be higher or lower? And the put premium in b)? Explain briefly.