Short selling is an investment term, such as stock futures spot: when investors expect a spot crude oil to fall in the future, sell your spot crude oil when the current price is high, and then buy it when the price falls to a certain extent. This difference is the investor's profit. Short selling is characterized by the trading behavior of selling first and then buying. Short selling is an important operation mode in stock and futures markets. This is the opposite of doing more. Theoretically, it is to sell the goods first and then buy them back. Generally, the regular short-selling market has a neutral warehouse to provide a platform for borrowing goods. This model can profit in the wave band of falling prices, that is, borrowing goods at a high level and selling them, and then buying and returning them after falling. In this way, the purchase is still low and the sale is still high, but the operating procedures are reversed.