In simple terms
Size is the quantity of a position. Depending on the instrument and platform, it may be stated in shares, coins, lots, contracts, or notional value.
Quantity is not risk
“Size 2” is incomplete because two contracts can have very different values and volatility. Margin and notional are not synonyms either: margin is capital required to support the position, while notional describes its reference value. Risk additionally depends on adverse movement, value per point, leverage, and costs.
“Too large” relative to what
A size is excessive relative to a loss limit, available liquidity, or total concentration—not a universal number. Position sizing starts with accepted risk and translates that limit into quantity. Size alone does not state maximum loss and cannot make unlike instruments directly comparable.
Sources
- CME Group, Position and Risk Management — Shows how contract choice, contract count, and stops affect risk.
- CME Group, Submitting a Futures Order — Treats quantity, order type, and execution as separate fields.