Let's guess the names of the Day, Pre, Regular, and After sessions first.

A session is a segment of trading hours. Connecting the abbreviations used in the community with the names on brokerage screens makes it easier to understand which time zone you are in. The abbreviations below are commonly used in Korea and are not official exchange terms.

1. 1

   Day market refers to US daytime trading. In the US, this corresponds to Overnight Trading. It is called daytime trading because it is used during the day in Korea, but the US regular market does not reopen during the day. Session names vary depending on the trading venue.

2. 2

   Pre/Pre-market refers to Pre-Market, which is trading before the market opens. It is the period for trading before the regular session begins.

3. 3

   The main session is the Regular Trading Hours (RTH). Depending on the exchange, the regular session is also called the Core Trading Session. It is usually open from 09:30 to 16:00 Eastern Time.

4. 4

   After-hours refers to trading after the regular market closes. 'App-jang' is not a term for trading via an app, but a nickname for the after-market.

Four-session schedule in KST

All times are in Korea Standard Time (KST) using a 24-hour clock. You can read it as a flow that starts from Monday afternoon and continues until Tuesday morning. 'Next day' refers to the day after the Korean date when the pre-market began.

Pre-market, regular market, and after-market hours are based on Nasdaq's standard trading days, while the day market is an example of Blue Ocean ATS's overnight operating hours converted to Korea Standard Time. These are not universal operating hours for all exchanges and brokerages, and they change on holidays, early closures, or maintenance days.

It shifts by one hour when daylight saving time changes.

ET is the collective name for U.S. Eastern Time. EDT (UTC−4) is used during daylight saving time, and EST (UTC−5) is used during standard time. Korea is on KST (UTC+9) year-round, so it is 13 hours and 14 hours ahead of U.S. Eastern Time, respectively.

Under current U.S. rules, daylight saving time starts on the second Sunday in March and ends on the first Sunday in November. In 2026, the dates are March 8 and November 1. The regular session opens at 9:30 a.m. ET in either season; in Korea, this corresponds to 22:30 KST during U.S. daylight saving time and 23:30 KST during standard time.

Based on the ET of the original schedule, Pre is 04:00–09:30,, Regular is 09:30–16:00,, and After is 16:00–20:00. The Blue Ocean ATS used in the Day example above operates from 20:00 the previous day to 04:00 on the same day. In other words, the American night becomes the next day in Korea.

Early morning in Korea corresponds to the previous trading day in the US.

For example, the US regular market on Tuesday, 10/20/2026, begins at 22:30 on 10/20 in Korea and ends at 05:00 on Wednesday, 10/21. The subsequent after-market session is from 05:00 to 09:00 on 10/21 in Korea. Even if the date changes in Korea, it may still be the same US trading day for after-hours trading.

Blue Ocean ATS generally operates during the overnight session, which begins on Sunday evening and runs through Thursday evening in the U.S. In Korea, this typically corresponds to daytime hours from Monday to Friday. Just because the U.S. regular session and after-market session on Friday extend into early Saturday morning in Korea does not mean the day market is open on Saturday afternoon.

Do not use this schedule on US holidays or early market close days. Korean and US holidays also differ. Please check the exchange schedule by date along with notices from your brokerage firm.

Can I trade all stocks according to the schedule?

Even if a market or ATS is open, your brokerage may not support that session. Supported stocks, order cut-off times, and maintenance windows may vary, and pre-orders are handled differently than trades that can be executed immediately.

Outside of regular trading hours, the bid-ask spread is wider and there are fewer counterparties, which may result in only partial execution or no execution at all. Some brokerages only accept limit orders. You should also check whether unfilled orders carry over to the next session or are automatically canceled.

Day, pre-market, and after-market prices do not guarantee the opening price of the next regular session. Even for the same stock, prices on the screen may differ depending on the connected trading venue and the timing of price data reception.

This schedule is based on information as of 2026/10/20. Nasdaq has announced the introduction of an overnight session from 21:00 to 04:00 ET starting 2026/12/6. This is a separate schedule with a different start time than the Blue Ocean ATS example above. Please verify actual implementation and your domestic brokerage's support announcements, and do not assume that all markets are open for 24 hours from now.

Check if the price on the screen is the most recently traded price.

The number shown as the current price may be the price of the most recent trade. If there have been no recent trades, the price from a few minutes ago may remain. An actual completed transaction is called an execution.

If prices appear frozen, check the market hours, last traded time, and data update time in that order. Different screens may display prices from different times.

Check what you have read.

• Have you checked which session is currently active: Day, Pre-market, Regular, or After-market?
• Have you checked whether daylight saving time is in effect and if the Korean date is marked as the 'next day'?
• Is it a US market holiday or an early closing day?
• Have you verified your brokerage's supported stocks, trading hours, and handling of unfilled orders?
• When was the last time the price changed?

Apply what you read to the actual screen

Try it on WAPE

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