Since the target of the contract is the stock price index, it is necessary to convert the index into monetary measurement. The size of the contract multiplier determines the value of each contract, and also determines the total number of contracts needed by the demand side to hedge the existing risks. Because the option contract is specially designed for the demander, the contract multiplier can be set according to the demander's demand, so as to facilitate the demander to determine the required number of contracts according to the total amount of risks to be hedged.