The pre-market session is a period of trading activity that occurs before the official opening of the regular trading session. Depending on the exchange, it typically starts several hours earlier and allows investors to place orders and react to news or events outside regular trading hours. For example, on the NYSE and NASDAQ, the pre-market session runs from 4:00 a.m. to 9:30 a.m. Eastern Time, while the regular session operates from 9:30 a.m. to 4:00 p.m.

One key difference is liquidity. During the pre-market session, trading volumes are significantly lower, as fewer participants are active. This can lead to wider bid-ask spreads and higher price volatility, making it riskier for traders. In contrast, the regular session sees higher liquidity, tighter spreads, and more stable price movements due to greater participation from institutional and retail investors.

Another distinction is accessibility. While institutional investors and professional traders often dominate the pre-market session, retail investors may face restrictions or higher broker fees to trade during this time. Additionally, not all stocks are available for pre-market trading, limiting opportunities compared to the regular session.

Overall, the pre-market session provides an early glimpse of market sentiment but carries higher risks due to lower liquidity and volatility, whereas the regular session offers a more robust and accessible trading environment.