(1) Close the position. Closing position is the behavior of stock index futures investors to buy or sell stock index futures contracts with the same variety, quantity and delivery month but opposite trading direction, so as to close the stock index futures trading. Closing a position in futures trading is equivalent to selling in stock trading. Because futures trading has a two-way trading mechanism, there are two kinds of closing positions: buying and closing positions (corresponding to selling and opening positions) and selling and closing positions (corresponding to buying and opening positions).

(2) holding positions. The open contract of stock index futures investors after opening positions is called open contract, also known as open position. After the stock index futures investors open their positions, there are two ways to close the stock index futures contract: either close the position in advance or hold it until the last trading day for cash delivery.

(3) Total market position. "Total market position" means the total number of "open contracts" of all investors in futures contracts (including long and short positions). Investors keep opening and closing positions when trading, so the total market positions are constantly changing. The total position of stock index futures market is calculated unilaterally, which is different from the bilateral calculation of commodity futures market at present. For example, in a trading contract, one investor buys the contract and holds it, while another investor sells the contract and holds it. The total position in the stock index futures market is shown as one contract, while the total position in the commodity futures market is shown as two contracts. The total market position is an important reference index for institutional investors to enter the market.

More trading information can also be viewed on Sina blog, a stock index trader.