one situation is that the futures customer still owes money to the futures exchange after closing the position. Because the market changes too fast, the deposit in the account can no longer maintain the original contract before the investor can add the deposit. This kind of deposit "zeroed" caused by forced liquidation due to insufficient deposit is commonly known as "short position", and the meaning of "short position" is the same as "short position". Another situation is the explosion of positions caused by heavy positions. This kind of situation is more common. For heavy position operations, such as the position ratio is above 9%, there is less capital that is not occupied, and there is less room to resist reverse changes. Heavy position operation is a way of quick profit and small loss. Because of the reverse change, if the margin is insufficient, the position will be exploded. This is because the software system will automatically close the stop loss.