Correlation: Why Five Trades Can Be One Trade
Trading five highly correlated instruments at full size is a single oversized bet wearing five different costumes.
Holding five positions feels diversified. If those five are all expressions of the same underlying bet, you are not diversified — you are leveraged, and you did not choose to be.
Correlation is the mechanism by which careful traders accidentally take far more risk than they intended.
What correlation measures
Correlation ranges from −1 to +1. A value near +1 means two instruments move together almost perfectly. Near zero means no linear relationship. Near −1 means they move in opposite directions.
For risk purposes, the sign is nearly as important as the strength. Two positions at +0.9 behave like one position at double size. Two at −0.9 partially cancel, which is genuinely useful.
Where hidden correlation hides
Currency pairs sharing a leg are the classic case. EUR/USD and GBP/USD both contain USD, so a dollar move hits both. Long EUR/USD and long GBP/USD is largely one large short-dollar position.
Cross-asset correlation is less obvious and more dangerous. Gold and the Swiss franc often respond to the same risk-off flows. Equity indices across regions correlate strongly during selloffs — which is exactly when you wanted the diversification to work.
Correlation is not stable
This is the part that catches professionals too. Correlations measured over calm periods frequently break or invert during stress. Assets that appeared independent suddenly move together because the same macro factor is driving all of them.
Plan for it. Measure correlation over multiple lookback windows, and assume that in a genuine crisis your diversification will be weaker than your data suggests rather than stronger.
Aggregate before you size
The practical fix is straightforward: before opening a new position, add it to your existing book and check what the combined exposure looks like. Not symbol by symbol, but as a portfolio.
If adding a position takes your net exposure in one direction beyond what you would knowingly risk, reduce the new position rather than justifying it. The Correlation Matrix tool on this site exists for exactly this check.
Forex Correlation Matrix
Asset Relationships • D1
| EUR/USD | GBP/USD | USD/JPY | USD/CHF | AUD/USD | USD/CAD | NZD/USD | EUR/GBP | EUR/JPY | GBP/JPY | AUD/JPY | CAD/JPY | CHF/JPY | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| EUR/USD | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| GBP/USD | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| USD/JPY | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| USD/CHF | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| AUD/USD | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| USD/CAD | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| NZD/USD | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| EUR/GBP | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| EUR/JPY | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| GBP/JPY | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| AUD/JPY | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| CAD/JPY | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| CHF/JPY | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
Three positions that look like three trades, and are closer to one
| Position | Correlation to first | Effective exposure |
|---|---|---|
| Long EUR/USD | — | 1.0× |
| Long GBP/USD | ≈ +0.85 | ≈ 1.85× short USD |
| Long AUD/USD | ≈ +0.75 | ≈ 2.6× short USD |
| Long XAU/USD | ≈ +0.4 | Partial diversification |
Key takeaways
- Two positions at +0.9 correlation behave like one position at double size
- Currency pairs sharing a leg are largely the same trade
- Correlations break and converge during stress, which is when you need them most
- Check combined portfolio exposure before opening anything new
- EUR/USD and GBP/USD frequently move together
- Gold and the Swiss franc often share the same risk-off driver
- Index CFDs across regions correlate strongly during risk events
- Aggregate your exposure before sizing any single position
Believing you are diversified because you are holding five different symbols.
Reading is not verification
Take the concept you just read and turn it into explicit rules, then test it. That is the only way to know whether it actually works.
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