Correlation Matrix Cheat Sheet
How to Read Correlation Values
| Correlation Range | Interpretation | Portfolio Impact |
|---|---|---|
| +0.70 to +1.00 | Strong positive — assets move together | Low diversification benefit |
| +0.30 to +0.69 | Moderate positive — some co-movement | Partial diversification |
| −0.29 to +0.29 | Low/no correlation — mostly independent | Good diversification |
| −0.30 to −0.69 | Moderate negative — tend to offset | Strong diversification |
| −0.70 to −1.00 | Strong negative — move opposite | Maximum diversification (hedge) |
Historical Asset Class Correlation Matrix
Based on long-term (20+ year) historical data. These are approximate ranges — correlations shift over time.
| US Stocks | Int’l Stocks | US Bonds | Real Estate | Commodities | Gold | Cash | |
|---|---|---|---|---|---|---|---|
| US Stocks | 1.00 | 0.75 | −0.10 | 0.55 | 0.30 | 0.05 | −0.05 |
| Int’l Stocks | 0.75 | 1.00 | −0.05 | 0.50 | 0.35 | 0.10 | −0.05 |
| US Bonds | −0.10 | −0.05 | 1.00 | 0.15 | −0.10 | 0.30 | 0.15 |
| Real Estate | 0.55 | 0.50 | 0.15 | 1.00 | 0.20 | 0.10 | 0.00 |
| Commodities | 0.30 | 0.35 | −0.10 | 0.20 | 1.00 | 0.40 | −0.10 |
| Gold | 0.05 | 0.10 | 0.30 | 0.10 | 0.40 | 1.00 | 0.05 |
| Cash | −0.05 | −0.05 | 0.15 | 0.00 | −0.10 | 0.05 | 1.00 |
Correlations During Market Crises
Correlations are not stable. During market stress, the diversification you counted on can evaporate.
| Asset Pair | Normal Correlation | Crisis Correlation | Change |
|---|---|---|---|
| US Stocks vs. Int’l Stocks | +0.75 | +0.90 to +0.95 | Rises sharply — global sell-offs |
| US Stocks vs. US Bonds | −0.10 | −0.30 to −0.50 | Becomes more negative — flight to safety |
| US Stocks vs. Real Estate | +0.55 | +0.80 to +0.90 | Rises sharply — 2008 proved this |
| US Stocks vs. Gold | +0.05 | −0.10 to −0.30 | Gold acts as safe haven |
| US Stocks vs. Commodities | +0.30 | +0.60 to +0.80 | Rises — demand-driven sell-off hits both |
Correlation & Diversification Math
Where w = weight, σ = standard deviation, and ρ = correlation. Lower ρ directly reduces portfolio variance — that’s the mathematical proof of why diversification works.
Practical Diversification Pairs
| Pairing | Typical Correlation | Why It Works |
|---|---|---|
| US Stocks + US Bonds | −0.10 | Classic 60/40 — bonds buffer stock declines |
| US Stocks + Gold | +0.05 | Gold provides crisis protection and inflation hedge |
| US Stocks + International Bonds | −0.15 | Currency diversification adds another layer |
| Stocks + Commodities + Bonds | Mixed low | Three-asset combo captures most diversification benefit |
Key Takeaways
- Correlation ranges from −1 to +1; lower correlation = better diversification
- US stocks and bonds have a slightly negative correlation — the foundation of balanced portfolios
- Correlations spike during crises, reducing diversification exactly when you need it most
- Gold and cash are the most reliable diversifiers during severe market stress
- Use rolling correlations rather than static historical averages for portfolio decisions
Frequently Asked Questions
What is a good correlation for diversification?
Below +0.30 is generally considered helpful for diversification. Below 0 (negative correlation) provides even stronger benefits. The ideal portfolio combines assets with the lowest possible correlations while still maintaining positive expected returns.
Why do correlations increase during market crashes?
During panics, investors sell everything to raise cash, creating a “sell everything” dynamic. Risk aversion overrides fundamental differences between asset classes. This is called “correlation convergence” and it’s one of the biggest challenges in portfolio construction.
How often should I recalculate my correlation matrix?
At minimum quarterly, but ideally use rolling 12-month or 36-month windows. Correlations can shift significantly due to changes in monetary policy, market cycles, or structural economic changes. What worked in 2015 may not apply in 2025.
Does adding more asset classes always improve diversification?
Not necessarily. If the new asset class is highly correlated with what you already own, it adds complexity without benefit. The incremental diversification benefit diminishes after 4–5 uncorrelated asset classes. Quality of diversification matters more than quantity.
How is correlation different from beta?
Correlation measures the direction and strength of the linear relationship between two assets (−1 to +1). Beta measures how much an asset moves relative to the market (can be any positive or negative number). Beta = Correlation × (σ asset ÷ σ market).