The difference is 65,438+02%. 300 yuan opened his position on 3 100, occupying 3 100 * 300 * 12 *. = 1 1. 160000 Because you are short, you can see the extra11.160000 on your books at this time. When the index will fall to 3000 points (before the last trading day of the contract), you can buy and close the position (as long as it is not in the daily limit or other special circumstances, don't worry too much about whether someone will take the order. At this time, you will get 100 points, which means that 300 yuan has made a profit of 30,000 yuan without considering other expenses. Although my explanation to you is not too standard and formal, you should be able to understand my friend.