A futures commodity has the largest contract transaction volume in a certain month, so this month's contract is the main contract. As the delivery date approaches, the trading volume will decrease, and this month's contract will lose its position as the main contract and be replaced by the contract with the largest trading volume in other months. This is the main contract conversion in the futures market.

The main contract is changed according to the change of its turnover and position. Let's look at the specific terms: 1, and only one main contract is selected for each variety. 2. The contract with the largest daily turnover and positions is determined as the new master contract, and the direction will be switched in the next trading day. 3. Keep the original master contract unchanged until a new master contract is generated according to Article 2. 4. If the volume and position of the current main company contract are not the largest, the current contract must give up the status of the main company contract, and the new main company points to the contract with the largest volume. Of course, when we look at the market, the software of the futures company will automatically switch the main contract.