An operation mode of stock and futures markets. 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.

For example, when you see 10 yuan's A shares, it is analyzed that its market outlook will fall to 8 yuan in a certain period of time, but you don't hold A shares. At this time, you can borrow some A shares from A-share holders and sign an agreement to return these borrowed shares to the original holders within a certain period of time. Suppose you borrow 100 A shares and sell them at the price of 10 yuan. Get 1000 yuan in cash. If the stock really falls to 8 yuan within the specified time, you use 8 yuan to buy 100 A shares, spend money to buy 800 yuan, and return 100 shares to the original holder. The number of shares of the original holder remains unchanged, and you earn 200 yuan cash. However, if the stock price rises to 12 yuan, you should buy 100 shares A at the price of 12 yuan, spend 1200 yuan, and return 100 shares to the original holder. The number of shares of the original holder has not changed, so you are short of 200 yuan cash.

There are short selling cases in the resources.