It should be that at present, investors entrust to buy or sell stocks in the trading system through stock software or telephone. In this way, the saleable quantity will be 0, because the transaction has been entrusted to a third party.

Futures is a kind of financial contract, including financial instruments or physical goods to be sold in commodity exchanges in the future. Futures is a derivative financial commodity. According to the types of spot subject matter, futures can be divided into commodity futures and financial futures. The commodity variety, trading unit, contract month, margin, quantity, quality, grade, delivery time and delivery place of futures contracts are all established and standardized, and the only variable is price.