Investing & Trading Glossary.
Learn 27 essential financial-market terms in plain English. Each definition is designed for study, with attention to risk, uncertainty and how financial instruments actually work.
Start with the concepts you need.
Use the subject links below to jump to definitions. This page is an introductory study reference, not a complete legal or technical definition of any financial instrument.
Market basics
- Bond
- A debt security representing an issuer’s obligation under specified terms. Bond investors face credit, interest-rate, inflation and sometimes liquidity risk.
- Index
- A rules-based or defined benchmark measuring a market or group of securities. An index itself is not ordinarily a security purchased directly.
- Exchange-traded fund (ETF)
- An investment fund whose shares typically trade on an exchange. Its strategy, holdings, operating expenses and principal risks vary by fund.
- Mutual fund
- An investment company that pools investors’ money under an objective. Conventional open-end mutual funds generally transact at the next calculated net asset value.
- Prospectus
- A formal disclosure document explaining an investment product’s objectives, strategies, risks and costs. Always check the current version.
Portfolio risk
- Asset allocation
- The distribution of a portfolio across categories such as stocks, bonds, cash or other exposures. Allocation does not eliminate investment risk.
- Diversification
- Holding different exposures to reduce reliance on a single security or risk driver. Diversification cannot prevent broad market losses.
- Correlation
- A statistical description of how returns move together. Relationships can change, particularly in periods of stress.
- Volatility
- The extent to which a price or return varies. Common measures describe historical variation and do not set a maximum possible loss.
- Drawdown
- The percentage decline in portfolio value from a prior peak to a subsequent low. Recovery gains are calculated from the smaller remaining balance.
- Position weight
- A position’s market value divided by the total portfolio value. It describes exposure, not a guaranteed ceiling on losses.
- Leverage
- Using borrowed money or derivative exposure to amplify gains and losses. Borrowing and some products can result in losses beyond the initial investment.
Trading mechanics
- Bid price
- A displayed price at which a buyer is offering to purchase a specified quantity of a security. Quotes can change.
- Ask price
- A displayed price at which a seller is offering to sell a specified quantity. It is not a guarantee of execution for an order of any size.
- Bid–ask spread
- The difference between the best displayed ask and bid. The spread can contribute to transaction costs and may widen under stress.
- Market order
- An instruction to transact at available market prices, generally prioritizing execution but not guaranteeing a price.
- Limit order
- An order that establishes a maximum buy price or minimum sell price but may remain partially or entirely unfilled.
- Stop order
- An order that becomes active when a specified trigger condition is met. A stop-market order does not guarantee the stop price.
- Slippage
- The difference between an anticipated and an achieved execution price. It may reflect moving markets, liquidity or the size and timing of an order.
Research and costs
- Expense ratio
- A fund’s annual operating expenses expressed as a percentage of assets. Trading costs and investor-specific taxes may be separate.
- Tracking difference
- The difference between an investment fund’s return and that of its benchmark over a specified period; causes can include fees and fund management mechanics.
- Liquidity
- How readily an asset can be transacted in meaningful size without materially changing its price. Liquidity varies by instrument and market conditions.
- Investment thesis
- A documented explanation of why an investment or market scenario might behave a certain way, ideally with evidence, assumptions and counterarguments.
- Primary source
- An original or authoritative source such as a filed company report, fund prospectus or official regulator bulletin, rather than an unsourced social summary.
Turn vocabulary into understanding.
Use the Market Literacy Capstone to check the concepts you remember, then work with hypothetical values in the Risk Math Lab. The four free Academy courses provide explanations and paper-only practice.
Original sources and methodology
For detailed product definitions and regulatory material, consult SEC Investor.gov and FINRA Investor Education. Our editorial standards explain how we separate evidence from interpretations.
If terminology differs in a current prospectus, exchange rulebook or broker agreement, review the authoritative document governing that particular product.
General education only. Definitions are simplified and are not personalized investment advice, forecasts, trade recommendations or guarantees. Financial markets involve risk and potential loss. Review disclosures.