Pre-Market and After-Hours Trading Explained

Pre-market and after-hours trading, together called extended-hours trading, is trading in listed stocks before the regular session opens and after it closes. Orders in these periods are matched electronically through exchanges’ extended sessions and alternative trading systems. The market is real, and prices printed there appear in “pre-market movers” lists, but conditions are different from the regular session. Liquidity is usually thinner, spreads are often wider, and prices can swing on small orders.

In brief

• Extended hours cover the periods before the open and after the close. Exact hours vary by exchange, venue and broker.
• Participation depends on the broker. Not every brokerage offers it, and many restrict order types.
• Volume is lower, spreads are typically wider and prices can be more volatile.
• Much of the activity is reaction to news, especially earnings releases issued outside regular hours.
• Extended-hours prices do not set the official opening or closing price, which come from the auctions.

How it works

During the regular session, orders flow to exchanges and other venues, and market makers add liquidity. Outside it, trading continues on a narrower set of systems. Exchanges operate pre-market and post-market sessions for their listed securities, and electronic communication networks and alternative trading systems match orders as well. Brokers connect their customers to some of these venues, and the hours they offer are set by the broker, which is why one platform may allow trading at an hour that another does not.

Orders are matched on the same basis as during the day: a buy order trades with a sell order at a compatible price. What differs is the number of participants. With fewer buyers and sellers, a market order can execute at a price far from the last trade.

The SEC’s investor education materials describe extended-hours trading as available to individual investors through many brokerages, with specific risks outlined in the sources below.

Why people trade in extended hours

• News reaction. Many companies release earnings after the market closes or before it opens. Extended hours lets traders react before the next regular session. This is the main source of pre-market movers lists.
• Global events. Overseas market moves, economic data and geopolitical developments can occur when U.S. markets are closed.
• Convenience. Some investors cannot trade during regular hours because of work schedules.
• Positioning. Institutions may adjust holdings around news or index events.

None of these reasons makes extended-hours prices a reliable guide to the next regular session. A pre-market move can fade or reverse once more participants arrive.

Risks identified by regulators

Both the SEC and FINRA have described risks of extended-hours trading to retail investors. The main ones are:

1. Lower liquidity. Fewer participants can make it harder to buy or sell at a desired price, or at all.
2. Wider spreads. The gap between the best bid and best ask is often larger, raising the effective cost of a trade.
3. Higher volatility. Prices can move sharply on small volumes, especially around news.
4. Price differences from the regular session. A stock’s price in extended hours may be very different from its price at the next open.
5. Competition from professionals. Institutional participants may have better information and tools.
6. News-driven uncertainty. Information released outside regular hours may be incompletely digested.
7. Data limits. Quotes shown on some websites may be delayed or reflect only part of the market, so the price displayed may not be one you can trade at.

For these reasons, regulators and brokers commonly recommend using limit orders rather than market orders in extended hours. A limit order sets the worst price at which the trade can execute. Some brokers accept only limit orders in these sessions, and orders may be canceled at the end of a session unless set otherwise.

How the pre-market movers list is built

Financial sites compile pre-market movers by ranking stocks by percentage price change versus the prior close, usually with filters for minimum volume or price. Because pre-market volume is thin, a stock can top the list on a few small trades. Reading such lists benefits from a few checks:

• Look at volume. A large percentage move on very low volume is less meaningful.
• Check the catalyst. Earnings, guidance, regulatory news, an analyst action or a financing announcement are common reasons.
• Compare with the prior close. Most lists measure change from the last regular-session close, not from the last extended-hours print.
• Check the data source. Different vendors capture different venues, so lists can differ.

Relationship to the opening auction

The official opening price is set by the opening auction on the stock’s primary listing exchange, not by pre-market trades. A pre-market price can indicate where a stock might open, but it is not a guarantee. The opening auction pools orders from all participants, many of whom join after the pre-market session. For the mechanics, see our guide to how opening and closing auctions work.

Likewise, the official closing price comes from the closing auction. After-hours trades occur later and do not change it.

A worked example (hypothetical)

A fictional company, Example Corp., closes the regular session at $40.00 and issues an earnings release shortly after. In the after-hours session, a handful of trades print at $43.00, and the bid and ask are $42.60 and $43.40. A market order to buy might fill near $43.40, which is $0.80 wide in spread terms. By the next morning, additional participants and analyst commentary arrive, and the opening auction sets the official open at $41.50. An investor who bought after hours at $43.40 faces a different position from one who waited for the auction. This does not indicate that either action is appropriate; it illustrates that extended-hours prices and the next open can differ. All figures are invented.

Common misconceptions

• “After-hours prices are the next day’s price.” They often are not. The open can differ.
• “Extended hours is a separate, unregulated market.” Trading in these sessions is subject to securities laws and exchange and FINRA rules, including requirements on best execution and manipulation.
• “Every broker offers it.” Availability, hours and order types vary.
• “A big pre-market percentage move means a big dollar move.” Low-priced or thinly traded stocks can show large percentage changes from small dollar amounts.
• “Only professionals trade then.” Retail access has grown, though professionals remain a large share of activity.

Practical checks before using extended hours

1. Read your broker’s disclosure on extended-hours trading, which regulators require brokers to provide in some cases.
2. Confirm the hours, supported order types and whether orders carry over.
3. Use limit orders and check the bid-ask spread before entering.
4. Look at volume and the news behind a move.
5. Remember that this guide is general education and not trading advice.

Key terms

• Bid and ask. The highest price a buyer will pay and the lowest price a seller will accept.
• Spread. The difference between the bid and the ask.
• Limit order. An order to buy or sell at a specified price or better.
• Market order. An order to trade at the best available price, which can be far from the last trade in thin markets.
• Electronic communication network (ECN). An automated system that matches orders outside the traditional exchange floor.
• Catalyst. The news or event behind a price move.

Earnings and extended hours

A large share of extended-hours activity follows quarterly results issued outside the regular session. The press release and the conference call can send different signals, and prices often adjust as analysts read the full filing. Readers who follow the numbers can use our guide on how to read an earnings release to work through the document behind the move before reacting to it.

How brokers handle extended-hours orders

Brokers typically require customers to acknowledge a disclosure about extended-hours risks before enabling it. Orders entered for the extended session may be limited to limit orders, may expire at the end of the session, and may route only to certain venues. A day order placed in the regular session usually does not carry into extended hours unless the customer selects that option. Because each broker’s policy differs, the same order can behave differently on two platforms. Reading the broker’s terms is the only reliable way to know how an order will be handled.

Execution quality also differs. Under SEC rules, brokers owe customers a duty of best execution for their orders, but in a thin market the best available price can still be unattractive. Customers can compare the quote they see with the last trade and the spread before submitting.

FAQ

What are the pre-market and after-hours trading hours?

They depend on the exchange, venue and broker. Check your broker’s disclosures and the exchange’s published hours for current times.

Can anyone trade in extended hours?

Anyone whose broker offers it, within that broker’s rules. Some brokers limit order types or require account approval.

Why do prices move so much outside regular hours?

Fewer participants means each order has a larger impact, and news often arrives when the regular market is closed.

Are extended-hours trades included in the daily volume and closing price?

Reports vary by data provider. The official close is set by the closing auction, and extended-hours trades do not alter it.

Should I use market orders in extended hours?

Regulators and brokers generally caution against it because of wide spreads and thin liquidity. A limit order controls the price you accept.