Insights · Reference

Glossary of algorithmic trading terms

Definitions of common algorithmic trading and market-structure terms, from adverse selection and basis to VWAP, slippage and walk-forward testing.

A to F

Adverse selection
The risk that the traders who fill your orders are better informed than you, so fills tend to come just before the price moves against you.
Alpha
Return that comes from skill or an informational edge rather than from general market movement.
API
Application programming interface. The machine-readable connection an exchange provides for market data and order entry.
Arbitrage
Buying and selling related instruments to profit from a price difference between them.
Backtest
A simulation of how a strategy would have performed on historical data.
Basis
The difference between the price of a derivative, such as a future, and the price of its underlying asset.
Bid-ask spread
The gap between the highest price a buyer will pay and the lowest price a seller will accept.
Co-location
Placing trading servers in the same data centre as an exchange’s matching engine to reduce latency.
Drawdown
A decline from a previous peak in the value of a strategy or account.
Fill
The execution of all or part of an order.
Funding rate
A periodic payment between long and short holders of a perpetual future that keeps its price close to the spot price.

K to O

Kill switch
A control that stops all trading and cancels open orders immediately.
Latency
The time taken for data or an order to travel between systems.
Limit order
An order to buy or sell at a specified price or better.
Liquidity
How easily an asset can be traded in size without moving its price.
Maker and taker
A maker adds a resting order to the book; a taker trades against one. Venues often charge them different fees.
Market impact
The movement in price caused by your own trading.
Market maker
A participant that continuously quotes both buy and sell prices.
Mean reversion
The tendency of a price to move back towards an average after moving away from it.
Momentum
The tendency of assets that have been rising, or falling, to continue doing so for a time.
Order book
The list of resting buy and sell orders on a venue, organised by price.
Overfitting
Tuning a model so closely to past data that it captures noise rather than a real effect.

P to Z

Perpetual future
A futures contract with no expiry date, common in digital-asset markets.
Position sizing
Deciding how large a position to take, usually based on risk rather than conviction.
Pre-trade controls
Automatic checks every order must pass before it is sent to a venue.
Reconciliation
Checking that a system’s internal records of orders, fills and balances match the venue’s records.
Sharpe ratio
Excess return divided by the volatility of returns.
Slippage
The difference between the expected price of a trade and the price actually achieved.
Statistical arbitrage
Trading on statistical relationships between instruments, expecting deviations to correct.
TWAP
Time-weighted average price. An execution approach that spreads an order evenly over time.
VWAP
Volume-weighted average price. An execution approach and benchmark weighted by traded volume.
Walk-forward testing
Repeatedly fitting a model on one period and testing it on the following period.

Sources and further reading

  1. Staff Report on Algorithmic Trading in U.S. Capital Markets · U.S. Securities and Exchange Commission
  2. FX execution algorithms and market functioning · Bank for International Settlements, Markets Committee

This article is for general information and education only. It is not investment advice, and it does not describe or solicit any product or service.