As for overnight or after the weekend, the price changes greatly, because of the limitation of trading time, the trend of foreign countries continues during domestic non-trading hours, which often leads to a sharp diving or a sharp opening after the opening of the market overnight.
The price fluctuation after the weekend is also due to the fact that after the suspension of trading, the influence of the outside world on some varieties was not reflected in the trend of varieties in time. For example, the earthquake in Chile occurred on the weekend. As soon as the market opened today, the price of copper rose.