Reference

Glossary of equity-trading terms.

Vocabulary that turns up across CFA and FRM curriculum, sell-side research notes, and active-trading literature. Each entry links to longer treatment where one exists.

ATR: Average True Range. A volatility measure averaging the daily high-low range (with gap adjustments) over a lookback period (typically 14 days). Used for stop-loss placement that scales with instrument-specific volatility. See the stop-loss page.
Beta: The sensitivity of a stock's return to broad-market return. Beta of 1.0 means the stock moves in line with the market; 1.5 means 50 % more; 0.5 means half as much.
Bid-ask spread: The difference between the highest price a buyer is willing to pay (bid) and the lowest price a seller is willing to accept (ask). The implicit transaction cost for a market order.
CFA: Chartered Financial Analyst. Designation administered by the CFA Institute covering portfolio management, financial reporting, and ethics.
Drawdown: The peak-to-trough decline of an account or portfolio. Maximum drawdown is the largest such decline observed over a period; the figure most retail traders should obsess over rather than headline returns.
Expectancy: Long-run average outcome per trade in R units: (win_rate × avg_win) − (loss_rate × avg_loss). The figure that determines whether a strategy is profitable. See the R:R page.
Fixed fractional: Position-sizing methodology that risks the same fixed percentage of account capital per trade. The default for retail traders. See the sizing rules page.
FRM: Financial Risk Manager. Designation administered by the Global Association of Risk Professionals (GARP) covering market, credit, and operational risk.
Kelly criterion: The mathematically-optimal sizing fraction given known win probability and win/loss size. f* = p/a − (1−p)/b. Brutal under estimation error; practical implementations use half-Kelly or quarter-Kelly.
Market on close (MOC): An order type that executes at the closing auction. Used by traders who want to be in or out at the official close print.
PDT: Pattern Day Trader. US FINRA designation for accounts executing 4+ day trades in 5 business days. Triggers a $25,000 minimum-equity requirement.
Position sizing: The decision of how many shares to buy in a trade. The most under-discussed determinant of long-run trading outcomes.
R: Shorthand for “risk per trade”. A 2R win is a win equal to twice the per-trade dollar risk. Used in expectancy reporting.
Risk-reward ratio (R:R): The ratio of potential reward (entry to target) to potential risk (entry to stop). Meaningless without a paired win-rate estimate.
SFC: Securities and Futures Commission. The Hong Kong securities regulator.
Slippage: The difference between expected and realised execution price. Particularly material for stop-loss orders during gap moves and after-hours sessions in less-liquid Asian-listed names.
Stop-loss: An order to close a position at a pre-defined loss level. The discipline that converts position sizing from theoretical to operational.
Volatility: Standard deviation of returns. Annualised by multiplying daily standard deviation by √252.
Wash sale: The IRS rule disallowing a loss for tax purposes if substantially identical securities are repurchased within 30 days. The disallowed loss is added to the new cost basis. See the tax page.