How to use this list
Each entry gives the definition and links to the page where the mechanism behind it is set out in full. The definitions are deliberately short: a glossary that explains everything stops being a glossary, and the explanation belongs on the page that can show the arithmetic.
Where a term means different things in different contexts, and market capitalization is the clearest case, meaning one arithmetic for a listed company and another for a token, the entry says so rather than choosing one and hoping.
The terms
- Round lot
- The standard trading unit on US equity exchanges: 100 shares. Public quotations are published in round-lot terms, and one listed equity option contract covers exactly one round lot.
- Options
- Odd lot
- Any quantity smaller than one round lot. Odd-lot orders execute normally but were historically reported separately and did not update the public quote, which is why the distinction survives in market-data documentation.
- Execution
- Tick size
- The smallest price increment a security may be quoted in. At low prices one tick is a large proportional move, which is most of what makes low-priced shares look volatile.
- Execution
- Bid-ask spread
- The gap between the highest price a buyer will pay and the lowest a seller will accept. Whoever crosses it pays it, on entry and again on exit.
- Execution
- NBBO
- The national best bid and offer: the best quote available across all US venues at a moment. Execution quality is measured against it.
- Brokers
- Strike
- The fixed price at which an option contract may be exercised. It is agreed when the contract is written and does not move.
- Options
- Intrinsic value
- The part of a premium already earned: for a call, the share price above the strike, floored at zero. It does not decay.
- Options
- Extrinsic value
- Everything in the premium above intrinsic value: compensation for remaining time and uncertainty. This is the part that decays, fastest at the end.
- Options
- Break-even
- The share price at which a position stops losing. Strike plus premium for a call; strike minus premium for a put. Never the strike alone.
- Tool
- DTE
- Days to expiry. A plain count of calendar days remaining on a contract, and one of the two inputs the extrinsic half of a premium is priced on.
- Options
- Assignment
- Being held to an option obligation because the holder exercised. For a seller it is the contract working as written, not an edge case.
- Options
- Delta
- The change in an option premium for a one-dollar change in the share price. Also read loosely as the probability of expiring in the money.
- Options
- Theta
- The change in an option premium for one day passing. Negative for a holder, because a day of possibility has been consumed.
- Options
- Implied volatility
- The figure at which the market is currently pricing the possibility of movement. Not a measurement of the past.
- Options
- Notional value
- The value of the stock a contract controls: strike times 100. It is the exposure, and it is what the small quoted premium disguises.
- Options
- Free float
- The shares genuinely available to trade, excluding founder, strategic and locked holdings. Often far below market capitalization at the small-cap end.
- Screening
- Market capitalization
- Share price times shares outstanding. For a token, price times circulating supply: the same label over different arithmetic.
- Screening
- Settlement date
- The day cash and ownership actually change hands. US equities settle at T+1, one business day after the trade.
- Execution
- Good faith violation
- Spending the proceeds of a sale in a cash account before they settle. Repeated, it leads a broker to restrict the account to settled cash.
- Execution
- Day-trading margin
- Equity a margin account must carry against its intraday exposure. Until 4 June 2026 the test was a count of four or more day trades in five business days plus a 25,000-dollar minimum; amendments to FINRA Rule 4210 replaced both with an intraday margin deficit measured against actual positions.
- Execution
- Accruals
- The gap between profit recognized and cash received. Comparing operating cash flow with net income is the most informative single test on a filing.
- Screening
- EBIT
- Earnings before interest and tax: operating profit before the capital structure and the tax position are applied. The largest term in the Altman Z-Score.
- Screening
- Interest coverage
- Operating profit divided by interest expense: how many times over current earnings pay current interest.
- Screening
- Covenant
- A promise about a financial ratio written into a debt agreement. Breaching one can make the balance immediately repayable, turning a slow decline into a sudden event.
- Screening
- Duration
- A bond’s sensitivity to yields, measured in years. A duration of seven means roughly a seven percent price fall per one point rise in yields.
- Screening
- Credit spread
- The extra yield a corporate bond offers over a government bond of the same maturity, compensating for default risk, expected loss and liquidity.
- Screening
- Market tier
- A classification by how much current information an issuer publishes. A disclosure regime, not a quality grade.
- Execution
- Dilution
- An increase in share count that shrinks each existing holder’s claim proportionally, even when the business is unchanged.
- Execution
- Attestation
- A report confirming stated balances existed at a stated moment. Narrower than an audit, which examines statements and controls over a period.
- Execution
About this glossary
Where do these definitions come from?
Exchange and clearing-house documentation, the standardized options disclosure material, and the original papers behind the published scores. Where a term has a settled meaning in that material, it is used; where common usage has drifted from it, the entry says so rather than picking the looser sense.
Why does my broker define one of these terms differently?
Because a platform's own glossary often describes what its software does, and a screener column label resolves choices the underlying standard leaves open. Neither is wrong; they are answering a narrower question. The entries here describe the mechanism, which is what stays true across platforms.
Are these legal definitions?
No. Every entry describes how a mechanism works, not how a regulator defines it. The two usually agree on substance and rarely agree on wording, and where a regulatory designation matters, such as an OTC tier or a current-information requirement, the page on that subject states it in full.
Why are some terms kept apart that everyone treats as the same?
Because each distinction marks a different obligation. A position opened by selling is written rather than sold, because something was committed that was never held. A short call with no shares behind it is uncovered rather than naked, because what is missing is the cover. Exercise is what a holder does and assignment is what happens to a writer, so the two are never swapped.
How is the list ordered?
Alphabetically, because a glossary is looked up rather than read through. Each entry links to the page where the mechanism behind it is set out in full, so the definition can stay short without leaving anything out.