Recently, someone asked me about pre-market trading in the US stock market, so I might as well share my understanding. To be honest, many retail investors don't realize how important this period really is.

Pre-market trading refers to trading activities that occur before the official market opens. The New York Stock Exchange and NASDAQ usually start accepting pre-market orders as early as 4 a.m. Eastern Time, until the official opening at 9:30 a.m. This period seems short, but it contains a huge amount of information. Corporate announcements, economic data, overseas market movements—these can all trigger sharp stock price fluctuations during pre-market hours.

Why is pre-market trading necessary? Essentially, it gives investors the chance to react to breaking news before the market officially opens. Imagine a company releases a major positive or negative report while you're sleeping; without pre-market trading, you'd have to wait until 9:30 a.m. to respond passively. With pre-market trading, you can adjust your strategy in advance. That's also why institutional investors pay special attention to this period.

I remember a case where a tech giant's stock dropped over 8% in pre-market trading because an important figure announced a reduction plan. By the time the market opened, this decline was already reflected in the opening price. This shows that pre-market trading can directly influence the opening price and sometimes even determine the overall trend of the day.

However, pre-market trading also has limitations. The most critical one is that only limit orders are allowed; market orders are not permitted. Why? Because participation is low, liquidity is poor, and using market orders could result in getting stuck at unfavorable prices. I personally experienced this myself and later realized that this rule is designed to protect investors.

Additionally, not all brokers support pre-market trading. Some start as early as 4 a.m., others at 7 a.m., and the time frames vary. When choosing a broker, you need to clarify this. I usually prefer brokers that support longer trading hours for greater flexibility.

As for after-hours trading, it occurs after the market closes, typically from 4 p.m. to 8 p.m. The logic is similar to pre-market trading: low liquidity and limited to limit orders. The difference is that after-hours trading mainly involves digesting and pricing the day's market movements, so the market tends to be calmer.

My trading strategy is as follows: First, closely monitor news events. Pay attention to company fundamentals regularly, and react immediately during pre-market if there’s significant news. Second, set reasonable limit prices. Due to low liquidity, I deliberately set buy prices lower than expected or sell prices higher than expected; sometimes this allows trades to execute unexpectedly well, yielding good returns.

Risk management is something I emphasize strongly: First, avoid large trades during pre-market and after-hours, as low volume can cause slippage; second, be cautious of extreme quotes—sometimes the prices you see are unreasonable; third, always stay alert to news, as this period can see big price swings, and a single piece of news can change the situation.

If you find the restrictions of pre- and after-hours trading too limiting, another option is CFDs (Contracts for Difference). CFD trading is not bound by exchange hours and can generally be traded 24 hours. However, this tool involves higher leverage and greater risk, so careful risk management is essential.

Overall, pre-market trading is a double-edged sword. Used well, it allows for early positioning; used poorly, it can lead to getting trapped. My advice is to start by observing, understand the logic of this period, and only when you’re confident enough should you start trading with real money.