It refers to the settlement system that the settlement department calculates and checks the balance of the margin account after the market closes every day, and keeps the balance of the margin above a certain level by issuing the notice of additional margin in time to prevent the debt from happening.

To put it bluntly, it is to calculate the profit and loss according to the daily settlement price, "retreat more and make up less". Daily equity changes are compared with the settlement price of the previous day.

Therefore, under the mark-to-market system, the average price of the position shown on the bill is the daily settlement price, so it is variable.

The other is "transaction hedging". If the "transaction hedging" system is adopted, then the average position price is the weighted average price of each opening price.