After the close of outstanding futures trading futures contracts to buy or sell a unilateral number. Open futures contracts are unique to the information, which expresses the number of existing warehouse merchandise, commodity trend is a perspective kinetic data. Buying and selling futures contracts and options contracts, the buyers and sellers of the contracts will be counted in the number of open contracts, and after the sale is completed, investors can wait for when the original contract expires, or the use of a contrast with the previous policy the responsibility to end the contract, known as liquidated. Because futures contracts traded in the exchanges will be protected, the buyers and sellers in the new contract will be open to deposit a bond to ensure that the obligation to be fulfilled, so the greater the number of open positions held by investors when, he needs to pay the margin will be higher, and the cost will be high, so if he believes the market outlook before the predicted is not the same, it will be open.