™Before the regular session, fewer displayed orders and wider spreads can make a headline-driven move less representative of a large executable price.
Trading
Premarket trading
Trading before the regular exchange session, often with lower liquidity and different risks.
Plain-English context
Put the definition to work.
A price printed before the regular session need not be available for your quantity or at your broker's venue.
Further reading and verification. Examples are hypothetical, not current quotes or recommendations. Product terms, tax treatment and market rules can change. FINRA — order types and execution