option (finance)

Options are financial instruments that convey the right, but not the obligation, to engage in a future transaction on some underlying security. For example, buying a call option provides the right to buy a specified quantity of a security at a set strike price at some time on or before expiration, while buying a put option provides the right to sell. Upon the option holder's choice to exercise the option, the party who sold, or wrote, the option must fulfill the terms of the contract.
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