Position Sizing: The Mathematics of Capital Allocation and Trade Survival

Encyclopedia Classification

Category: Risk Management • Capital Allocation • Trading Mathematics

Discipline: Portfolio Management • Probability • Volatility Adjustment • Compounding

Prerequisites

• Article 180 — Risk Management: The Foundation of Professional Trading

• Article 179 — Investor Psychology: Fear, Greed, Cognitive Biases, and the Mental Game of Trading

• Article 176 — Fibonacci Analysis: The Complete Guide to Retracements, Extensions, and Market Targets

Related Articles

Risk Management • Leverage • Portfolio Construction • Expected Value • Algorithmic Trading • Trading Systems

Definition

Position sizing is the process of determining how much capital to allocate to a specific trade.

It answers one of the most important trading questions:

"How much should I risk on this idea?"

Position sizing determines:

• Survival.

• Drawdown.

• Emotional pressure.

• Long-term profitability.

• Ability to compound capital.

Beginner Explanation

Two traders can have:

• The same entry.

• The same strategy.

• The same chart.

One succeeds.

One fails.

The difference may simply be:

Position size.

Example:

Trader A risks:

1%

per trade.

Trader B risks:

20%

per trade.

Both lose five trades.

Trader A:

Down approximately 5%.

Still operating.

Trader B:

Account severely damaged.

Recovery becomes difficult.

The strategy was not the difference.

The sizing was.