First of all, you have to understand the nature of futures. In the vernacular, futures are standard sales contracts. Except for the price, other contract contents are agreed upon, and you can't change them.

Opening a position is actually signing a contract with the other party. For example, buying the Shanghai and Shenzhen 300 Index 10 in March means that you are the buyer. You fill in 1450 yuan in the blank of the contract price and sign 10 copies of the same contract. Your rival seller agrees to sell it to you at this price, and the quantity is also 10 contract.

Closing a position can be understood as the transfer of a contract. For example, closing 5% is to sell the contract you originally held to others. If someone else buys your contract, you have to make up the difference of 1500 yuan. So you lose the right to five contracts after closing the position, so you only have five contracts left.

If you follow the above operation, in fact, you did not transfer five contracts to others, but signed five new sales contracts with other buyers as a seller. So, you have 10 contracts as the buyer and 5 contracts as the seller. There is a 15 contract.