A derivative contract giving the buyer the right, but not the obligation, to buy or sell a specific asset, index, rate or instrument at a specified price within a certain time period. It is unilateral because only one party (the buyer) has the right to demand performance on the contract. If the buyer exercises his right, the seller (writer or grantor) must fulfil his obligation at the strike price, regardless of the current market price of the asset. See Derivative; European Option; American Option
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