The original margin is the fixed minimum capital charged by the exchange for opening positions, while the maintenance margin is a certain discount of the fixed margin and is also fixed. For example, the original margin of Hang Seng Index futures is about 57,000 yuan/piece, and the maintenance margin is about 47,000 yuan/piece. The exchange will fine-tune it at any time according to market conditions. If the original margin minus the loss value is greater than the maintenance margin, the futures company will generally not close the position immediately when the customer suffers losses, and will only inform the customer to add the margin. However, if the original margin MINUS the loss value is less than the maintenance margin, the futures company will not only issue an insurance recovery notice, but also maintain the right to close the position immediately.
Time deposit is a product of history. Before electronic transactions are widely used, in order to quickly calculate and judge the risk status of customers, it is the only feasible method to adopt fixed margin, otherwise it will bring a lot of time-consuming calculation and dynamic judgment. In the era of electronic trading, customers can place their own orders, and the dynamic calculation of position margin is no longer a problem when the exchange mainframe and futures company server are large enough and fast enough. Therefore, commodity futures and stock index futures in emerging markets often adopt proportional margin system. 2. The so-called proportional margin refers to the opening margin dynamically calculated in a fixed proportion according to the contract value, that is, the margin is calculated according to the following formula: opening margin = stock index futures point × contract multiplier × margin ratio × number of transactions, where the contract multiplier represents the equivalent value of 1 index point. The contract multiplier of Shanghai and Shenzhen 300 index futures is set as 300 yuan.
The proportional margin system is the trend of market development, because it can keep the risks of futures companies and exchanges at a certain level all the time, while the fixed margin system can not meet such requirements. If the fixed margin system wants to ensure that the risks of exchanges and futures companies are always within the controllable and acceptable range, only by setting the original margin high enough to make the index fluctuate at the highest level that can be expected can the customer margin still be guaranteed to be no less than a certain order of magnitude (for example, 6%). When the index is at a low level, the utilization rate of market funds is low, which leads to the decrease of market efficiency. The solution to this problem is that the exchange adjusts the size of the fixed margin according to the level of the index, but this involves new efficiency problems, because the index may rise to a higher level soon after lowering the margin level, forcing the exchange to adjust again in the short term. There is not much difference between the exchange's frequent adjustment of margin and the computer's calculation of margin according to a fixed ratio.