9.1 Why Position Size Is the Core of Risk Management
Even with high-probability setups and solid stop‑loss discipline, position sizing determines whether a signal delivers growth—or ruins you. As Investopedia puts it, “Position sizing is the glue that holds together a sound trading system” and ensures traders stay alive to exploit their edge.
Proper position sizing balances:
Account risk: maximum percent you’re willing to lose per trade (commonly 1–2%).
Asset volatility: high-volatility ETFs need smaller sizes.
Correlation exposure: don’t overweight similar assets; spread across uncorrelated ETFs.
9.2 Core Position-Sizing Methods
We’ll apply two practical sizing methods in our framework:
A. Fixed Percentage per Trade
Define a max risk per trade (e.g., 1% of total account).
Example: €10,000 account → €100 max risk.
With ATR-based stop (e.g., €4 per share), buy €100 ÷ €4 = 25 shares.
B. Volatility-Based / Risk Parity
Allocate risk equally across different ETF types.
Inversely weight position size by asset volatility (using ATR or standard deviation).
For example, if bonds have half the volatility of stocks, invest twice as much in bonds to equalize risk contributions.
This helps align with your 80/20 core–satellite mix and reduces overweighting volatile sectors.
9.3 Advanced: Risk-Parity Allocation & Portfolio Construction
For your Core Sleeve, consider a simple risk-parity approach to give each asset stream equal contribution to overall portfolio volatility:
Calculate historical volatility or ATR for each sleeve.
Invert the numbers to get weightings (e.g., Highest-volatility gets smaller weight).
Normalize so weights sum to 80% (core).
Use remaining 20% for satellite trades, sized individually with fixed percent or ATR rules.
This reduces concentration in high-volatility ETFs and smooths out portfolio-level risk.
9.4 Correlation & Optimal Exposure
Even perfectly sized, overexposure to highly correlated ETFs spikes risk. Modern portfolio theory (MPT) teaches that it’s how an ETF behaves with others—not just how volatile it is—that matters (Investopedia).
Use simple correlation matrix tools (available in many platforms) to ensure your core assets are diversified—e.g., equities vs. bonds vs. commodities average correlation near zero or negative. Periodically review and adjust sizes accordingly.
9.5 Practical Step-by-Step Sizing Workflow
Define your max % risk per trade—start at 1%.
For satellite trades:
Calculate ATR-based stop size.
Position size = (Account × %risk) ÷ (ATR × multiplier).
For core sleeves:
Compute 30–90 day volatilities.
Inverse weight allocations across core ETF groups.
Correlate core ETFs to ensure <0.3 average correlation.
Adjust exposure if your strategy sees satellite trade clusters that concentrate risk. Use smaller % per position to keep overall portfolio risk within plan.
9.6 Sample Calculation
Assume €10,000 total:
Core Equity ETF volatility = 16%; Core Bond ETF = 8%; Core Commodity ETF = 12%.
Inverse volatilities:
Equity: 1/0.16 = 6.25
Bonds: 1/0.08 = 12.5
Commodity: 1/0.12 = 8.33
Total = 27.08 units; normalize to 80% of portfolio:
Equity: (6.25 ÷ 27.08) × 80% ≈ 18.5% allocation
Bonds: 37%
Commodity: 24.6%
Satellite trades sized at 1% per position, using ATR stops.
9.7 Position Sizing Pitfalls to Avoid
Ignoring volatility: leads to oversized, high-risk positions with unstable assets.
Overlooking correlation: multiple ETF positions could act as one, inflating exposure.
Risk creep: satellite trades can slowly absorb core capital—check monthly total risk exposure.
Lack of standardization: consistency in sizing across strategies is crucial; avoid gut-driven variation.
9.8 Action Plan for Chapter 9
Decide your risk % per satellite trade (1–2%).
Calculate ATR-based sizing: record ATR, compute share size, enter trades.
Build a spreadsheet for core: input recent volatilities, compute inverse weights, determine allocations.
Run correlation check: ensure average pairing <0.3.
Simulate combined satellite/core sizing: check max drawdown impact.
Note and adjust: if risk seems too high, reduce satellite fraction or reduce fixed % per trade.
Not Financial Advice
This article is for informational purposes only and does not constitute financial advice. Always conduct your own research before making any investment decisions.
