The four sessions, briefly
Regular session: 9:30am-4:00pm ET, all major US exchanges, full consolidated tape. Pre-market: roughly 4:00am-9:30am ET, lit exchange order books, limit orders only at most brokers. After-hours: 4:00pm-8:00pm ET, lit exchange order books, limit orders only.
Overnight (24/5): roughly 8:00pm-4:00am ET, a defined eligible-ticker list, routed to an alternative trading system such as Blue Ocean ATS, limit orders only. Sunday evening through Friday evening; closed on US holidays.
Which brokers support which sessions
Almost every retail broker supports the standard pre-market and after-hours extended-hours sessions, though the exact hours differ. Fidelity and Schwab open pre-market at 7:00am for retail accounts; Webull, Moomoo, Robinhood and Interactive Brokers open as early as 4:00am. After-hours runs to 8:00pm at almost every mainstream broker.
24-hour trading is the smaller universe. Charles Schwab routes a defined list of S&P 500 and Nasdaq-100 names through thinkorswim. Interactive Brokers offers IBKR Overnight Trading on the Blue Ocean ATS for ~10,000 US-listed names. Robinhood operates 24 Hour Market on a similar set of large-caps and ETFs. Webull, Moomoo and Firstrade have launched competing 24-hour offerings.
The eligible-ticker list at every 24-hour broker is a strict subset of the US universe — typically large-cap index constituents plus the most liquid ETFs. Small-caps, OTC and most ADRs are not eligible.
- Pre-market 4am-9:30am — Webull, Moomoo, Robinhood, IBKR (most)
- Pre-market 7am-9:30am — Fidelity, Schwab (default)
- After-hours 4pm-8pm — virtually every retail broker
- 24-hour overnight — Schwab, IBKR, Robinhood, Firstrade, Webull, Moomoo
Order types and restrictions
Limit orders are mandatory in all extended sessions at every broker. Market orders are either rejected, auto-converted to marketable limits at a percentage band, or queued for the next regular open. Stop orders and stop-limit orders are generally disabled — the stop-trigger price feeds depend on regular-session quotes.
Short-sale execution is more restricted outside regular hours. SEC Rule 201 (the alternative uptick rule) can be triggered overnight and persist through the next session; some brokers disable shorting entirely in pre-market and after-hours regardless. Option exercises and assignments do not happen in extended hours — only the underlying equity trades.
Order-routing for extended hours typically uses the broker's default ECN or smart router. Direct-market-access brokers expose the ECN choice (ARCA, EDGX) to the trader; mainstream brokers route automatically.
Liquidity and the price-discovery question
Pre-market and after-hours volumes are typically 1-5% of regular-session volume on the same name. Overnight 24/5 volume is even thinner — often a fraction of 1% of regular-session volume. The implication is mechanical: bid-ask spreads widen, depth at any single price level is shallow, and a market-impact-aware approach is essential.
Earnings releases and macro data routinely produce 5-15% moves in extended hours. Those prints are noisy signals about the next regular open, not finished moves. Many traders treat extended-hours action as a price-discovery signal rather than a place to take meaningful positions. For long-term investors, the practical default is: do not trade in extended hours unless you have a specific reason.
Tax, settlement and edge-case mechanics
Extended-hours trades settle on the same standard T+1 cycle as regular-session trades. Trade date is the calendar date the trade executed in US Eastern Time — so an overnight fill at 2:00am ET is dated that calendar day, not the previous one. This matters for wash-sale tracking and year-end tax-loss harvesting.
Corporate actions (dividends, splits, spinoffs) take effect at the regular session open on the ex-date. Holding through extended hours into ex-date does not entitle a trader to the dividend if the position was opened in the after-hours of the day before ex-date.