Limit up is a term in the securities market. The price limit system originated from the early foreign securities market. It is a trading system in the securities market to properly limit the price rise and fall of each stock on the same day in order to prevent the price from soaring and plunging and curb excessive speculation. It stipulates that the maximum fluctuation range of the trading price in a trading day is a few percent of the closing price of the previous trading day. That is, the highest price and the lowest price of the day's transaction are stipulated. In the China A-share market, there are limits on the increase and decrease, and the range is 1% of the closing price of the previous day.