StrategyIntermediate#Risk Management#Core Concept
Position Sizing
P
Definition
The process of setting an intended exposure for a position. It requires explicit assumptions about price, instrument, leverage, liquidity, costs, correlations, and loss tolerance; no universal percentage or formula is suitable for every account or product.
Source reviewed
- SEC Investor Bulletin: Trading Basics opens in a new tab
Supports: Explains market-order price is not guaranteed and limit orders may not execute, relevant to position-size assumptions based on entry or stop levels.
- Investor.gov: Asset Allocation and Diversification opens in a new tab
Supports: Explains that allocation depends on time horizon and risk tolerance and that diversification is a risk-management practice rather than an outcome guarantee.
Concept Diagram
Key Takeaways
1
Position size is a proposed exposure under stated assumptions, not a universal percent-of-account rule
2
Cash, leverage, collateral, liquidation, fees, gaps, execution, correlation, custody, and venue risk can change realized loss
3
One-percent, two-percent, fixed-fractional, and Kelly approaches are models, not safety standards or personalized advice
4
Recalculate exposure when instrument, liquidity, leverage, costs, portfolio concentration, or loss tolerance changes
Practical Example
A cash-market plan divides a chosen loss amount by its planned price distance to calculate a proposed quantity. Before acting, the user adds fees, spread, expected slippage, execution limits, and related positions. If the product is leveraged, they also review collateral, liquidation, funding, and venue rules rather than treating the chart stop as a fixed maximum loss.
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