For example, in the Notice on Listing and Trading of Shanghai and Shenzhen 300 Stock Index Futures Contracts, CICC stipulates that the margin of stock index futures contracts is 10%.

If you have 10000 yuan and 5,000 yuan as the opening deposit (the remaining 5,000 yuan is used to cover the loss), you can make a contract of 50,000 yuan. If you go long, when the stock index fluctuates downward by 10%, it is a loss of 5000 yuan. This will force you to close your position.