Stock exchanges publish more than one set of hours. The one most people know is the regular session, which on the NYSE and Nasdaq runs from 9:30 AM to 4:00 PM Eastern Time. Around it sit two shorter windows, usually called pre-market and after-hours. They are real, but they work differently.
The three windows
Pre-market is the period before the opening bell. US exchanges publish early trading windows that begin as early as 4:00 AM Eastern Time, running up to the 9:30 AM open.
Regular hours are the core session. This is when the opening and closing auctions take place and when the most participants are active.
After-hours begins at the 4:00 PM close and, on the exchange side, can run until 8:00 PM Eastern Time.
The schedule table on each market page on this site lists these windows next to the regular session, in the exchange's timezone and in yours. See the NYSE page for an example.
Why the windows are labeled as varying by broker
An exchange publishing a window does not mean every broker offers it. Brokers choose their own extended-hours windows, and many start later or end earlier than the exchange. Some also limit which order types are accepted outside the regular session. For that reason this site labels pre-market and after-hours spans as varying by broker, and you should check your own broker's rules for the exact times.
How the sessions typically differ
Differences between extended hours and the regular session are structural rather than a rule of thumb:
- Participation. Fewer buyers and sellers are active before the open and after the close, so there is typically less liquidity.
- Spreads. The gap between the best buy price and the best sell price is often wider when fewer orders are resting in the book.
- Price movement. News released outside the regular session, such as earnings announcements, tends to reach the market in these windows, and prices can move noticeably on small volume.
- Auctions. The opening and closing auctions happen at the edges of the regular session, which is one reason regular hours are the reference for official opening and closing prices.
None of this predicts what any price will do. It describes how the market is built, so you know which window you are looking at when a number appears on a screen.
Early closes and holidays
On days with an early close, the regular session ends sooner, often at 1:00 PM Eastern Time, and the extended-hours windows around it can differ from a normal day, so read the exchange notice for that date. On a market holiday there is no regular session at all. The NYSE holiday calendar lists both kinds of day.
Reading a status on this site
The status badge on a market page shows Pre-market, Open, After-hours, or Closed as plain text, so you can tell at a glance which window you are in. The countdown beside it shows when the next change happens. A busy stretch right after the regular open is covered on the US cash open page.
Market hours on this site are for reference only. Verify with the official exchange before trading.