The position that is the opposite of a purchased call is a written call. A seller of a call option is said to be the option writer, or to have a short position. The call option writer is the counterparty to the option buyer, and his payoffs and prots are just the opposite of those of the call option buyer. \ Similarly, the position that is the opposite of a purchased put option is a written put option. Again, the payoff and prot for a written put are just the opposite of those of the purchased put. \ It is important to note that the opposite of a purchased call is NOT the purchased put. If you do not see why, please draw a payoff diagram with a purchased call and a purchased put.