According to the requirements of the exchange, the new listing contract should guarantee the virtual second contract. Therefore, the month of soybean oil listing is generally five contracts.

When the price fluctuates so much on one day that the existing contract cannot guarantee the use of "virtual second gear", it will be added the next day.

The principle of adding and hanging always ensures "virtual second gear"

For example, on May 3, 50ETF closed at 2. 16 and 1607. The original maximum exercise price of the contract is only 2.2000, which is not enough for the closing price of 2. 16. So on June 1 day, a subscription and put contract of 2.2500 was added.