Pre-market, Regular Hours and After-Hours

Regular trading: 9:30–16:00 US Eastern

US trading hours are in US Eastern time. At the 9:30 open and the 16:00 close the exchanges each run a call auction to set the opening and closing prices; there's no lunch break in between.

Pre-market and after-hours: fewer traders, wider spreads

extended-hours trading are usually 4:00–9:30 and 16:00–20:00, but which sessions are open depends on your broker. Fewer people trade, the spread is often wide, and many brokers only accept limit order.

Daylight saving: both sides change their clocks

The US observes daylight saving time (from the second Sunday of March to the first Sunday of November). London changes its clocks too, so in London time the US market opens at 14:30 almost all year; only in the few weeks when the two change on different dates is it 1 hour earlier.

Key takeaways

• The regular session is 9:30–16:00 Eastern Time; the exchanges run an auction at the open and at the close to set the opening and closing prices.
• Pre-market (usually 4:00–9:30) and after-hours (usually 16:00–20:00) have fewer participants and wider spreads; many brokers only accept limit orders, and hours vary by broker.
• US daylight saving time runs from the second Sunday in March to the first Sunday in November. London changes its clocks too, so the open is usually 14:30 London time, except for a few weeks a year when the two countries change on different dates and it's 13:30.

Try it yourself

You can do these exercises in this lesson's interactive simulation:

1. Drag the time to 7:00 (US Eastern): which session is this? What should you watch out for if you order now?
2. Drag to 9:30: how is the opening price set?
3. Set “My time zone” to London and switch between summer and winter: how much does the opening time change?
4. Switch to Tokyo or Seoul and look again: what local time is the close?

Quiz and explanations

1. In July, what time does the regular US session open in London?

Answer: 14:30.In July both the US and the UK are on summer time and New York is 5 hours behind London, so the 9:30 open is 14:30 in London.

2. What should you watch out for most when trading after hours?

Answer: There are fewer participants, so the bid-ask spread can be wide.Pre-market and after-hours liquidity is thin and the bid-ask spread is often much wider than in the regular session, so it's best to control your fill price with a limit order.

3. Compared with the week before, what happens to the US open in London time after the first Sunday in November?

Answer: 1 hour later.The UK goes back to winter time a week earlier (last Sunday in October), so for that week the open is 13:30 in London; once US clocks go back on the first Sunday in November, it returns to 14:30, one hour later.

Terms in this lesson

• call auction (Call Auction): Orders are collected for a while without trading, then all matched at once at a single price, often used at the open and close.
• continuous trading (Continuous Trading): Normal trading after the open: each new order is matched against the order book as soon as it arrives, so the price changes with every trade.
• daylight saving time (Daylight Saving Time): The US moves clocks forward 1 hour on the second Sunday of March and back on the first Sunday of November. The US opening time doesn't change, but in Asian time it shifts by 1 hour.
• extended-hours trading (Extended-Hours Trading): Trading sessions outside regular hours (such as US pre-market and after-hours). Fewer people trade, the bid-ask spread is wider and prices can swing more sharply.
• limit order (Limit Order): An order that only fills at your price or better: the price is guaranteed, the fill isn't.
• trading hours (Trading Hours): The time each day when the exchange accepts orders and matches trades, usually split into an opening auction, continuous trading, a lunch break and a closing auction, varying by market.
• spread (Spread): The gap between the Ask and the Bid, a hidden cost on every trade.