Correlation Risk: Hidden Overexposure
Being long EUR/USD and long GBP/USD isn't two trades. It's one trade at double the size.
Researched and written by Laurent The Hidden Risk
You have $10,000 and risk 1% ($100) on a long EUR/USD trade. Then you see a nice setup on GBP/USD and risk another 1% ($100). You think you're risking 2% across two independent trades.
But EUR/USD and GBP/USD are approximately 80% correlated. Both pairs move primarily based on USD strength or weakness. If USD strengthens, BOTH trades lose simultaneously. Your actual exposure is closer to 2% on a single bet (USD weakness), not two independent 1% bets.
Understanding Correlation
| Correlation | Meaning | Example |
|---|---|---|
| +1.00 | Perfectly correlated (move together exactly) | Theoretical only |
| +0.80 | Strongly correlated (usually move together) | EUR/USD and GBP/USD |
| +0.50 | Moderately correlated | EUR/USD and AUD/USD |
| 0.00 | No correlation (independent) | EUR/USD and USD/JPY (roughly) |
| -0.90 | Strongly inverse (move opposite) | EUR/USD and USD/CHF, strongly negative (often around -0.9) |
Major-Pair Correlation Matrix
Here are typical rolling 90-day correlations between the seven most-traded pairs. Treat this table as an illustrative snapshot: correlations shift with market regime, so recompute them for your own timeframe and lookback window before relying on them:
| EUR/USD | GBP/USD | AUD/USD | NZD/USD | USD/JPY | USD/CHF | USD/CAD | |
|---|---|---|---|---|---|---|---|
| EUR/USD | 1.00 | +0.82 | +0.65 | +0.58 | -0.10 | -0.90 | -0.55 |
| GBP/USD | +0.82 | 1.00 | +0.60 | +0.52 | -0.08 | -0.75 | -0.45 |
| AUD/USD | +0.65 | +0.60 | 1.00 | +0.88 | -0.20 | -0.60 | -0.55 |
| NZD/USD | +0.58 | +0.52 | +0.88 | 1.00 | -0.18 | -0.55 | -0.50 |
| USD/JPY | -0.10 | -0.08 | -0.20 | -0.18 | 1.00 | +0.45 | +0.40 |
| USD/CHF | -0.90 | -0.75 | -0.60 | -0.55 | +0.45 | 1.00 | +0.50 |
| USD/CAD | -0.55 | -0.45 | -0.55 | -0.50 | +0.40 | +0.50 | 1.00 |
Green = positive correlation. Red = negative. Darker = stronger. Always recompute for your own timeframe and lookback window before risking capital.
Three things jump out:
- EUR/USD and USD/CHF, strongly negative (often around -0.9): nearly perfect inverse. Long EUR/USD and long USD/CHF means you have effectively no position.
- AUD/USD and NZD/USD at +0.88: two trades on this pair are almost one trade. Size accordingly.
- USD/JPY is the odd one out: low correlation to most other pairs because JPY moves on risk sentiment and rate differentials more than on USD strength alone.
Practical Rules
- Correlation above +0.70: Treat as the same trade. Risk should be shared, not stacked.
- Correlation between +0.30 and +0.70: Partially correlated. You can hold both but reduce size.
- Correlation near zero: Truly independent trades. Full risk on each is acceptable.
- Correlation below -0.70: Opposing trades. Being long both effectively cancels out your position.
Key Takeaways
- • EUR/USD and GBP/USD are historically around 80% positively correlated. Being long both doubles your USD risk.
- • USD/CHF and EUR/USD are strongly negatively correlated (often around -0.9). Being short one and long the other is the same trade.
- • Check correlation before opening a second position. Above 70% = same trade, effectively.
- • Max correlated exposure: 2 positions maximum in the same directional bet.