When the market situation changes greatly, if most of the funds in the margin account are occupied by trading margin, the trading direction is opposite to the market trend, and it is easy to explode because of the leverage effect of margin trading.
There are two kinds of empty positions. One case is that the futures customer still owes money to the futures exchange after closing the position, that is, the floating profit and loss of the account is ≥ the total amount of funds in the account, that is, the customer's equity is ≤0.
The second situation is that the market changes so fast that the deposit in the account can no longer maintain the original contract before the margin is added. This kind of margin "zeroing" caused by forced liquidation due to insufficient margin is commonly known as "short position", and the meaning of "short position" is the same as "short position".