Same industry, different rules
Put a chart of Samsung Electronics or SK Hynix, Korea's leading large-cap chipmakers, next to a chart of a large US tech stock and you will see similar candles and moving averages. But the two charts are drawn under different rules. How far a price can move in a day, when the market is open, how the open and close are set, and the smallest step a price can take all differ. If you read indicators the same way without knowing this, a shape that is normal on a Korean chart can look strange on a US chart, and the other way round. The stocks named here are only examples for reading charts.
Price limits: ±30% versus none
A Korean stock can move only up to 30% above or below the previous close in a day. The band was widened from ±15% in June 2015 and has stayed there since, but rules can change, so check the official information. Once a stock hits the limit it cannot move further that day, and the leftover pressure can carry into the next day, producing several candles in the same direction. Individual US stocks have no such daily cap. When big news comes out, all of it lands in a single daily candle, so the day after an earnings report can produce a candle of a length rarely seen in Korea. It also means the news is often fully priced within a day.
Mechanisms that pause sharp moves
No price limit does not mean the US market has no safeguards. Both countries have mechanisms that briefly halt trading or change how it works, for single stocks and for the whole market. The details can change, so treat these as concepts.
- Korean volatility interruption: when a single stock moves sharply in a short time, it briefly switches to single-price trading
- Korean circuit breaker: when the index falls sharply, trading in the whole market is paused
- US single-stock pause: when a stock moves outside a set band too quickly, trading in it stops briefly
- US circuit breakers: drops of 7%, 13% and 20% in the S&P 500 from the previous close trigger market-wide halts in stages
Trading hours and call auctions
The Korean regular session runs from 9:00 a.m. to 3:30 p.m. Orders collected from 8:30 to 9:00 a.m. set the open at a single price, and the close is set the same way from 3:20 to 3:30 p.m. So the open and close on a Korean daily candle come from single-price matching. In 2025 an alternative trading venue opened, adding trading time before and after the regular session, so check the official information for eligible stocks and hours. US exchanges also run opening and closing auctions that match collected orders at one price, but extended hours are long, and whether those prices appear on a chart depends on the settings.
Tick sizes and candle shapes
The tick size is the smallest step a price can move. Korean stocks have different tick sizes for different price bands, so the size of one step relative to the price depends on where the stock trades. US stocks priced at one dollar or more usually trade in one-cent steps. For a high-priced US large cap, one step is tiny compared with the price, so intraday candles look dense and smooth, while a low-priced Korean stock can look like a staircase because each step is relatively large. The two countries also often use opposite color conventions for rising and falling candles, so check the legend first when using an overseas chart service.
What to check when comparing the two
When you compare a Korean stock and a US stock on one screen, line up the following first so you are reading them on the same basis.
- Dates: US daily candles carry the US date, one day off from the Korean date
- Currency: do not compare won and dollar prices directly; use returns or rebase both to 100 on the same day
- Days that hit the price limit: read the next few days on the Korean chart with that in mind
- Candle color conventions: they vary by service, so check the legend
- Adjusted prices: make sure dividends and splits are handled the same way
Check it with this site's live tools
The large-cap scanner puts major Korean and US stocks in the same table with daily change, RSI, moving average alignment and distance from the 52-week high, which makes it easy to compare the two markets at a glance. The stock comparison tool rebases assets in different currencies, such as Samsung Electronics and a US index, to 100 on the same day, and the buy and sell signals tool applies the same indicator rules to Korean and US stocks alike. Prices may be delayed.
Things to keep in mind
This guide explains why charts in the two markets look different and is not investment advice. Price limits, circuit breaker thresholds, trading hours and tick sizes are all rules that can change. Before you trade, check the official information from the Korea Exchange, the US exchanges and your broker. And remember that in a market without daily price limits, there is no daily limit on losses either.
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