Short selling, also known as short selling (in Hong Kong terms) and short selling (in Singapore and Malaysia terms), is an investment term for stocks, futures and foreign exchange, and also a mode of operation in the stock and futures markets. In contrast to bulls, in theory, it is to borrow goods to sell first and then buy them back. Short selling refers to selling stocks at the current price in the expectation of future market decline, and buying them after the market decline to obtain the difference profit. Its trading behavior is characterized by selling first and then buying. In fact, it is a bit like the credit transaction model in business. 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. For example, a stock is expected to fall in the future, borrowed and sold when the current price is high (the actual transaction is to buy a put contract), then bought when the stock price falls to a certain extent and returned to the seller at the current price. The difference is the profit.