Note that, generally speaking, the trading volume before and after the market is small, which will lead to a big difference between the buying price and selling price of market makers, which often means that you have to buy stocks at a more expensive price or sell stocks at a lower price in the trading before and after the market, mainly due to liquidity. The better time to participate in pre-market and after-market trading is that some events happened outside the trading hours of the company, which led to substantial changes in the stock price.
Extended data
Characteristics of US stocks in different trading hours
From 9: 30 to 9: 45, these fifteen minutes are called "spare time", and large institutions usually enter after 9:45. During this period, brokers and market makers will execute customers' liquidation orders, which is one of the most unstable moments of the day.
10: 00 is called the "critical reversal moment". Many economic data will be released at 10, and the market often reverses at this moment.
These two hours (11:30-1:30) are called "lunch time". During this period, the more powerful market makers will go out for lunch and order assistants to do nothing but provide liquidity, so the turnover during this period will be relatively small. It is unlikely that there will be a smooth sailing trend during this period, and the sideways situation is more common.
1:30-4:00 is "professional time", and many institutional investors will choose to enter the market during "professional time". During this period, the most powerful market makers and brokers will continue to execute customers' liquidation orders and trade their company accounts. In addition, it should be noted that 2:30 is another key trading moment, and many strong trends often begin at this time.
At 4 o'clock, the US stock market closed.
Baidu encyclopedia-American stocks