Put-Call Parity Asserts That a Combination of a Long Position

Essay

Put-call parity asserts that a combination of a long position in the stock and the put produces the same return as a comparable position in a call and a risk-free bond. If not, at least one market is in disequilibrium. The resulting arbitrage alters the securities' prices until the value of the stock plus the put equals the prices of the call and the bond. The successful use of arbitrage assumes the investor of a profit no matter what happens to the price of the stock.

Put-call parity also asserts that if an arbitrage opportunity does not exist, then a combination of the stock and the put produces the same return as the comparable position in the call and the risk-free bond. Currently, the price of a stock is $70 while the price of a call option at $70 is $6; the price of the put option at $70 is $2, and the price of a discounted bond is $66. Verify that a long position in the stock and the put produces the same performance as a long position in the call and the bond for the following prices of the stock: $60, 65, 70, 75, and 80.