In stock and futures trading, call auction is relative to continuous bidding. The so-called call auction refers to the time specified by the exchange (stock 09: 15 ~ 09: 25, commodity futures 08: 55 ~ 08: 59, stock index futures 09: 10 ~ 09: 14), when all investors' orders or commissions are entered into the quotation system. However, at the end of the matching trading time (09: 25 ~ 09: 30), each stock or futures contract will take the trading price set by the exchange as the opening price, and at the same time, the list that can be closed will be matched to the maximum extent at this price.

Generally speaking, the closing principle of continuous bidding is: the first price takes precedence, and the second price takes precedence. In call auction, the principle of clinching a deal is: the first volume takes precedence, the second price takes precedence, and the third time takes precedence. To put it simply, bidding auction "offers first, then matches, then closes", while continuous bidding is "offers, matches and closes". Open call auction is adopted for stocks, and closed call auction is adopted for futures. Previously, the China stock market implemented a closed call auction. July 2006 1 After the implementation of the new trading rules, the open call auction mechanism was implemented.

Open call auction is a more transparent call auction model, which is conducive to improving the participation of ordinary investors in the call auction stage and their willingness to trade before and after the opening, thus effectively improving market liquidity, making call auction pricing more efficient and increasing the manipulation cost of the opening price. According to the statistics of some experts, compared with last month, the transaction volume ratio increased by 20.8%, the transaction amount ratio increased by 14.5%, the zero transaction ratio in call auction decreased by 53.7%, and the opening pricing efficiency index increased by 5.8%. China Futures implements closed call auction, mainly because

There are long and short sides in futures, and the continuous game between long and short sides makes the price less easy to be manipulated. Therefore, the possibility of price manipulation will not increase because of closed bidding. The price trend in futures is generally the real result after the fierce game of long and short main forces. (2) Retail investors are not encouraged to participate in the quotation in call auction time, but the long-short main players can determine the opening price through secret games, and retail investors can participate after the opening. As the futures trading system is T+0, retail investors can look for opportunities at any price after the market opening, and can buy and sell for many times without having to participate in call auction.