For example, in CZCE's wheat contract, when the price rises (falls) in one trading day, the price rises (falls) in the next trading day will be expanded by 50%. If the original price rises or falls by 3%, it will be 4.5% after expansion.
The daily limit is only one-way, that is to say, if the first day is the daily limit, the next day's increase is 4.5%, and the decline is still 3%.
Generally speaking, board expansion is only carried out after the first board stop (it varies from switch to switch). If the board is still closed after the daily limit, the price will remain unchanged the next day (according to the price after the daily limit, all transactions are different). If the daily limit is in one direction for three consecutive days, the exchange will take trading restriction measures such as increasing the margin ratio, limiting the opening of positions, reducing the ups and downs until the forced liquidation. To control risk.
The purpose of board expansion measures is to release the Boli kinetic energy of trading funds as soon as possible.