Sessions
Pre-market closing-price trading (08:30–08:40) uses the previous close; post-market closing-price trading (15:40–16:00) uses the same-day close. After-hours single-price trading (16:00–18:00) runs an auction every 10 minutes within ±10% of the day's close.
Why use it
Investors react to earnings or filings released after the close, or trade at close-level prices when they missed the regular session.
What to keep in mind
Volume is thin, so orders may not fill. A big after-hours gain does not guarantee the stock will open higher the next day.
This explanation is general information, not investment advice. Rules reflect September 2026 and may change; check official exchange and broker notices.