Extended Hours
Trading sessions before the open and after the close, with far less liquidity.
Also called: pre-market · premarket · after-hours · after hours
In plain language
Pre-market and after-hours sessions let participants react to news released outside the regular session, but only a fraction of normal volume participates.
Spreads widen dramatically, order books thin out, and prices can move substantially on very small trades.
Extended-hours prices often fail to hold. A stock up 8% after hours can open flat once the full market weighs in.
Why it matters
Market orders in extended hours can fill catastrophically far from the quoted price, and many order types behave differently or are unavailable.
Common mistakes
- Using market orders in thin extended-hours conditions.
- Treating an after-hours price as a reliable indication of the next open.
- Assuming stop orders are active outside regular hours. Often they are not.
Keep exploring
These concepts are connected. Understanding one usually makes the next one easier.
How easily an asset can be bought or sold without moving its price.
The gap between the bid and the ask — the built-in cost of entering a trade.
A jump between one period’s close and the next period’s open with no trading in between.
A company’s scheduled quarterly disclosure of financial results.
The instruction that says how long an order stays active before it expires.