Stock Glossary — stock, chart and US market terms explained

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Stock basics

StockStock, Share: A small unit of ownership in a company. Shareholders receive dividends when the company shares its profits and can vote at shareholder meetings. Stock basics →
Shareholder: A person who owns a company’s shares. You own a part of the company in proportion to the shares you hold.
Listing: Registering a company’s shares on an exchange so anyone can buy and sell them. Listed companies must disclose key information such as results regularly.
IPOInitial Public Offering: The process of a company selling shares to the public for the first time and getting listed. In Korea, investors apply for allocations through a public offering subscription.
Market capitalizationMarket Capitalization: Share price × shares outstanding. It is the whole company valued at today’s market price, so a high share price does not by itself mean a big company.
Par valuePar Value: The nominal amount printed on a share. It has almost nothing to do with the actual trading price.
Common and preferred stockCommon / Preferred Stock: Common stock is the ordinary kind; preferred stock usually has no voting rights but pays a slightly higher dividend. In Korea, preferred shares have “우” after the name.
Dividend: Part of a company’s profit paid out to shareholders. The company decides it and can cut or stop it. Dividend calculator →
Dividend yieldDividend Yield: Annual dividend per share ÷ share price. If the price falls while the dividend stays the same, the yield goes up.
Ex-dividend dateEx-dividend Date: The first day on which buying the stock no longer gets you the upcoming dividend. In theory the price may adjust down by about the dividend.
ETFExchange Traded Fund: A fund that tracks an index or an asset and trades on an exchange like a stock. It spreads one purchase across many holdings.
Index: A single number that combines the prices of many stocks to show how the market is doing. Examples include the KOSPI, S&P 500 and Nasdaq Composite.
KOSPI and KOSDAQKOSPI / KOSDAQ: Korea’s stock markets. KOSPI is mostly large companies; KOSDAQ has many growth and small-to-mid-sized companies. Each also has an index of the same name.
Cash balanceCash Balance: The cash in your brokerage account. Money from a sale only arrives on the settlement date (two trading days later for Korean stocks).
Rights offeringRights Offering: A company issuing and selling new shares for money. With more shares, existing shareholders’ stakes can shrink.
Bonus issueBonus Issue: Giving existing shareholders new shares for free. The price adjusts for the extra shares, so the company itself is not worth more.
Stock splitStock Split: Splitting one share into several. The price per share drops and shares get easier to buy, but the market cap stays the same.
Share buybackShare Buyback: A company buying its own shares on the market. If the repurchased shares are cancelled, each remaining share represents a bigger slice.
Short sellingShort Selling: Selling borrowed shares first and buying them back later to return. It profits only if the price falls, and losses have no limit if the price rises.

Orders & trading

Buy and sellBuy / Sell: Buying is purchasing shares; selling is disposing of them.
Bid and askBid / Ask: The price buyers are offering (bid) and the price sellers are asking (ask). The order book shows how many shares are waiting at each price.
Tick sizeTick Size: The smallest price step you can order at. Korean stocks use steps such as ₩1, ₩5, ₩10, ₩50 and ₩100 depending on the price range; US stocks usually move in 1-cent steps.
Limit orderLimit Order: An order with a set price. It fills only at that price or better, and not at all if the price never gets there.
Market orderMarket Order: An order that fills right away at the prices currently available. In thinly traded stocks it can fill at a worse price than expected.
Filled and unfilled ordersFill / Unfilled: An order is filled when it meets an opposite order and a trade happens. Orders still waiting are unfilled and can be cancelled or changed.
Bid-ask spreadBid-Ask Spread: The gap between the lowest ask and the highest bid. It tends to be wider for thinly traded stocks.
Volume: The number of shares traded over a period. It often rises when the price moves sharply. Candles & volume →
Trading valueTrading Value: The amount of money traded (the sum of price × quantity). It is better than volume for comparing activity between stocks with different prices.
Liquidity: How easily you can buy or sell when you want, near the price you want. With low liquidity, selling can be hard or push the price down a lot.
Call auctionCall Auction: Collecting orders for a set time and filling them all at one price. Korean stocks use it before the open (08:30–09:00) and just before the close (15:20–15:30).
Daily price limitsPrice Limit: The most a price can move in a day. For Korean stocks it is ±30% from the previous close. US stocks have no such limit but pause trading during sudden swings.
Settlement dateSettlement (T+2, T+1): The day the shares and money actually change hands. Korean stocks settle two trading days later (T+2); US stocks have settled one day later (T+1) since May 2024.
Stop lossStop Loss: Selling at a price set in advance so a loss does not grow. The key is setting the rule beforehand and keeping it — you can practice this in mock trading. Mock trading →
Averaging downAveraging Down: Buying more after the price falls below your purchase price to lower your average cost. The average drops, but you have more money at stake, so further falls hurt more. Average cost calculator →
Scaling in and outScaling In / Out: Buying or selling in several steps instead of all at once. It keeps the result from depending on the price at one moment.
Average costAverage Cost: The average price paid per share across several purchases. It is sometimes calculated including fees.
Return: Profit as a share of the money invested. Losses and gains are not symmetric: after −50%, you need +100% to get back to where you started. Return calculator →
Unrealized and realized P&LUnrealized / Realized P&L: Unrealized P&L is the gain or loss on shares you still hold at today’s price; realized P&L is what is locked in once you sell.
Margin tradingMargin Trading: Buying shares with money borrowed from your broker. Losses can exceed your own money, and the broker can sell your shares if collateral runs short (forced liquidation).
Forced liquidationForced Liquidation: The broker selling a customer’s shares when a loan cannot be repaid or collateral falls short. The shares are usually sold near market price, which can deepen losses.

Charts

Candlestick: One bar showing a period’s open, high, low and close. The body spans the open and close; the wicks reach the high and low. Candles & volume →
Up and down candlesUp / Down Candle: A candle is up if the close is above the open and down if below. Korean charts draw up candles red and down candles blue; US charts usually use green and red.
Open, high, low, closeOpen, High, Low, Close: The first, highest, lowest and last traded prices of the period. Most indicators are calculated from the close.
WickWick, Shadow: The lines above and below a candle body. A long upper wick means the price rose and was pushed back; a long lower wick means it fell and recovered.
Daily, weekly and monthly chartsDaily / Weekly / Monthly: Charts where each candle covers a day, a week or a month. Use longer ones for the big picture and shorter ones for detail.
Trend: A price movement that continues in one direction. Rising highs and lows mean an uptrend; falling highs and lows mean a downtrend. Trendlines →
Trendline: A line joining lows (uptrend) or highs (downtrend). It depends on which points you connect, so there is no single right answer. Trendlines →
Support and resistanceSupport / Resistance: Price zones where the price stopped and bounced several times (support) or was blocked several times (resistance). Think of them as zones rather than exact prices. Support & resistance →
Trading rangeTrading Range: When the price moves up and down within set limits. Also called a sideways market; trend-following signals often contradict each other here.
Breakout and breakdownBreakout / Breakdown: Moving above resistance is a breakout; falling below support is a breakdown. Many are false and quickly reverse.
Gap: An empty space on the chart when the next open is far from the previous close. It often happens when big news such as earnings comes out while the market is closed.
Pullback: A temporary dip during an uptrend. Whether the trend continues or ends is only clear afterwards.
Double bottom and double topDouble Bottom / Top: A shape with two bottoms (or tops) at similar prices. It is usually considered complete only once the price passes the middle high (or low). Chart patterns →
Head and shouldersHead and Shoulders: Three peaks with the middle one highest. A break below the neckline joining the two troughs is read as a sign the uptrend is weakening. Chart patterns →
Moving average alignmentMA Alignment: When shorter moving averages sit above longer ones in order, the alignment is bullish; the reverse order is bearish. Moving averages →
Golden cross and death crossGolden / Death Cross: A short moving average crossing above a long one is a golden cross; crossing below is a death cross. In sideways markets they often flip back and forth. Moving averages →

Indicators

Technical indicatorTechnical Indicator: A value calculated from price and volume that shows the market in another way. All are based on past data, so none tells the future. Learning path →
Moving averageMoving Average (SMA, EMA): A line joining the average close of the last N days. The simple average (SMA) and the exponential average (EMA), which weights recent prices more, are the most common. Moving averages →
RSIRelative Strength Index: Compares recent gains with recent losses on a 0–100 scale. Above 70 is often called overbought and below 30 oversold. RSI →
Overbought and oversoldOverbought / Oversold: Words for a price that has risen or fallen a lot in a short time. In strong trends it can stay there for long, so it does not mean a turn is coming.
StochasticStochastic Oscillator: Shows where the close sits within the recent high–low range on a 0–100 scale. Read %K together with its average, %D. Stochastic →
MACDMoving Average Convergence Divergence: The difference between a short and a long exponential moving average. Comparing it with its own average (the signal line) shows whether momentum is growing or fading. MACD →
Bollinger Bands: Bands drawn a set number of standard deviations above and below a moving average. Narrow bands mean volatility has dropped; wide bands mean it has risen. Bollinger Bands →
Divergence: When price and an indicator point in different directions — for example, the price makes a new high while the RSI high is lower. Often the trend simply continues.
LagLagging: Indicators move later than the price. Longer periods are smoother but react more slowly.
Whipsaw: When the price moves the other way right after a signal, so the signal turns out wrong. Common in directionless markets.
Volatility: How widely the price swings. Volatile stocks can produce large gains and large losses over the same period.

Earnings & valuation

Revenue: The total money a company earns from selling goods and services, before costs.
Operating incomeOperating Income: Revenue minus the cost of goods and selling and administrative expenses. It shows how much the core business earns.
Net incomeNet Income: The profit left after interest, taxes and everything else are taken out of operating income.
EPSEarnings Per Share: Net income ÷ number of shares. The profit earned by one share in a year.
P/E ratioPrice to Earnings Ratio: Share price ÷ EPS — how many times earnings the price is. Fair levels vary widely by industry and growth outlook, so be careful with simple comparisons.
P/B ratioPrice to Book Ratio: Share price ÷ book value per share. Below 1 means it trades below book net assets, though there is often a reason.
ROEReturn on Equity: Net income ÷ shareholders’ equity — how much the company earned in a year on the money shareholders put in.
Debt ratioDebt Ratio: Liabilities ÷ equity. Higher means more reliance on borrowed money; normal levels differ by industry.
Earnings releaseEarnings Release: When a company reports its quarterly or annual revenue and profit. Prices often move sharply around it. US market calendar →
Consensus: The average of analysts’ earnings forecasts. Even good results can push the price down if they fall short of it.
Earnings surprise and missEarnings Surprise / Miss: Results well above the consensus are a surprise; well below are a miss (often called an “earnings shock” in Korea).
Guidance: A company’s own outlook for the next quarter or year. In US earnings, guidance can move the price as much as the past results.
Fiscal yearFiscal Year: The 12-month period a company uses to report results. Many do not use January–December, so the same season can be called something like “fiscal 2027 Q1”.

Markets & economy

Policy ratePolicy Rate: The benchmark interest rate set by a central bank. Higher rates raise borrowing costs and often weigh on stocks.
FOMCFederal Open Market Committee: The Federal Reserve meeting that sets US interest rates. It meets eight times a year, and markets worldwide watch the outcome. US market calendar →
CPIConsumer Price Index: An inflation measure of how prices of goods and services bought by consumers change. The US CPI comes out monthly and strongly affects rate expectations. US market calendar →
PCE price indexPersonal Consumption Expenditures Price Index: The US personal consumption expenditures price measure, which the Fed uses to judge its 2% inflation target.
Jobs reportEmployment Situation: The monthly US Labor Department employment report: nonfarm jobs added, the unemployment rate and wage growth.
GDPGross Domestic Product: The total value added in a country over a period, showing the size and growth of the economy. The US releases it in three estimates each quarter.
Inflation: A general rise in prices. The same money buys less.
Recession: A significant decline in economic activity lasting a while. Two quarters in a row of falling GDP is often used as a rough rule.
Bull and bear marketsBull / Bear Market: A long rising period is a bull market; a long falling one is a bear market. A drop of 20% or more from a peak is often called a bear market.
Circuit breakerCircuit Breaker: A mechanism that halts trading for a while when a market index falls sharply in a short time, to slow down panic-driven selling.
VIXVolatility Index: The volatility the market expects over the next 30 days (annualized %), calculated from S&P 500 option prices. It rises when markets are nervous, hence the nickname “fear index”. Dividing the VIX by 16 gives a rough expected daily move (%). Textbook ch.13: volatility and the fear index →
VKOSPI: The expected 30-day volatility from KOSPI 200 option prices, published by the Korea Exchange — the “Korean VIX”. It rises when the Korean market is nervous. Textbook ch.13: volatility and the fear index →
Fear & Greed IndexFear & Greed Index (CNN): A CNN market sentiment index that combines seven measures, including momentum, new highs, the put/call ratio, the VIX and junk bond demand, on a 0–100 scale. Near 0 means fear and near 100 greed. It is not the same as the VIX. Textbook ch.13: volatility and the fear index →
Implied volatilityImplied Volatility (IV): The market’s expectation, built into option prices, of how much a price will move. Unlike historical volatility from past prices, it looks forward; the VIX is made from S&P 500 implied volatility.
Exchange rateExchange Rate: The rate at which two currencies are swapped. US stocks are bought in dollars, so a change in the won–dollar rate changes your return in won even if the stock price does not move.

US stocks

TickerTicker Symbol: The short letter code for a US stock — for example AAPL for Apple and NVDA for NVIDIA. Korean stocks use six-digit numeric codes.
Regular, pre-market and after-hours sessionsRegular / Pre-market / After-hours: The US regular session runs 09:30–16:00 local time. You can also trade before and after, but thin trading can make prices jump. US stock basics →
NYSE and NasdaqNYSE / NASDAQ: The two main US exchanges. Many Big Tech companies are listed on Nasdaq.
S&P 500, Nasdaq-100 and DowS&P 500 / Nasdaq-100 / Dow Jones: The S&P 500 covers about 500 large US companies, the Nasdaq-100 the 100 largest non-financial Nasdaq stocks, and the Dow 30 leading large companies.
Fractional sharesFractional Shares: Buying part of a share, like 0.1 share, by amount. Many Korean brokers offer fractional trading in US stocks.
Big Tech and the Magnificent SevenBig Tech, Magnificent Seven: Very large US technology companies. The Magnificent Seven are Apple, Microsoft, Alphabet, Amazon, NVIDIA, Meta and Tesla.
ADRAmerican Depositary Receipt: A certificate that lets shares of a non-US company trade in dollars on a US exchange. TSMC and ASML trade in the US this way.
Volatility trading pausesLimit Up-Limit Down (LULD): US stocks have no daily price limits; instead, trading in a stock briefly pauses if its price leaves a set band within a short time.

Taxes & costs

Commission: The fee you pay your broker to buy or sell. It varies by broker and method and is usually higher for foreign stocks than Korean ones.
Securities transaction taxSecurities Transaction Tax: A Korean tax on the sale amount when you sell Korean stocks, charged even without a profit. The rate varies by market and year (to be confirmed).
Capital gains tax on foreign stocksCapital Gains Tax: In Korea, a year’s gains from selling foreign stocks, minus ₩2.5 million, are taxed at 22% (including local income tax) and reported yourself the next May (may change with tax law; to be confirmed). Foreign stock tax calculator →
Dividend taxDividend Tax: Korean stock dividends are paid after 15.4% withholding (including local tax). US dividends have 15% withheld in the US, which is above the Korean rate, so usually nothing more is due (to be confirmed). Dividend calculator →
Comprehensive financial income taxationComprehensive Financial Income Tax: In Korea, if interest and dividends together exceed ₩20 million a year, the excess is added to other income and taxed at progressive rates.
Currency exchange feeFX Spread: The cost of converting won to dollars (or back). You pay it on both the buy and the sell, so frequent short-term trading adds up.