A call option is a financial contract between two parties, the buyer and the seller of this type of
option. Often it is simply labeled a "call". The buyer of the option has the right, but not the obligation to buy an agreed quantity of a particular
commodity or
financial instrument (the
underlying instrument) from the seller of the option at a certain time (the expiration date) for a certain price (the
strike price). The seller (or "writer") is obligated to sell the commodity or financial instrument should the buyer so decide. The buyer pays a fee (called a premium) for this right.
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