Short selling refers to the increase in investment varieties, but investors did not buy or sell prematurely and did not enjoy the return brought by the increase in investment varieties. However, stepping on the air shows that investors are right, but they have no trading rights.
In the stock market, shorting refers to the stock market rising, but the stock was originally thrown out and was not bought in time for some reason. This phenomenon is called stepping on the air. The stock has gone up, and if you don't buy it or make a profit by shorting it, it's called stepping on the air. It has nothing to do with "empty". When the share price of a stock goes up all the way, it is judged that the share price will fall back in the afternoon, so I throw this stock, and I want to buy back the thrown stock at a low price. Who knows that the stock price has not fallen, but has been rising. In this way, this "high throw and low catch" foot is "empty".