Margin is the minimum (basic) transaction amount stipulated by the exchange. At the same time, according to the trading rules, futures companies can increase by 3 percentage points on this basis. In theory, futures companies can collect deposits like exchanges, but in actual transactions, because speculation (the most obvious is continuous suspension) is difficult to control, futures companies have to pay a certain amount of deposits in exchanges. In order to safeguard their legitimate interests, futures companies generally charge higher basic margin than exchanges to control market risks and safeguard their own interests. When the market risk increases, the trading ownership will temporarily or regularly increase the trading margin. Then, the futures company can also increase the margin accordingly. Popular understanding: the behavior of futures companies is equivalent to building a slow pool or dam on a fast-flowing river.