1. Initial margin: the margin that machine investors need to pay when opening positions, with the purpose of establishing future positions. There are 4,000 places to join the CSI 300, and the initial deposit requirement is 8%, so the capital needed to establish future positions is 4,000× 300× 8% = 96,000 yuan.

2. Maintenance margin: When the market is unfavorable, the exchange requires to continue to hold future positions's margin. If it is lower than the maintenance margin, the investor's position will be closed. Generally speaking, the maintenance margin ratio will be lower than 75% of the initial margin.

3. Additional margin: refers to the margin that investors need to continue to add when their losses reach a certain level to avoid being forced to close their positions by the exchange in the future.