Pre-market trading is the period of trading activity that occurs before the regular market session opens. On US exchanges, pre-market trading can start as early as 4:00 AM Eastern Time, though most retail brokers provide access starting at 7:00 or 8:00 AM ET. During pre-market hours, trading volume is significantly lower than the regular session, typically representing only 5-10% of normal volume. This leads to wider bid-ask spreads and potentially more volatile price movements. Pre-market is particularly active when companies release earnings reports before the opening bell, as traders rush to price in new information. Only limit orders are typically accepted during pre-market, protecting traders from extreme price swings. The pre-market session serves as an important price discovery mechanism, giving traders clues about how the regular session will open based on overnight developments and early-morning news.