Currency Correlation: The Hidden Double Bet

Currency correlation measures how closely two pairs move in relation to each other — some pairs tend to move in the same direction, others in opposite directions, and some show little relationship at all.

Positive and negative correlation

Positively correlated pairs (like EUR/USD and GBP/USD) tend to move in the same direction, often because they share a common currency or similar economic drivers. Negatively correlated pairs (like EUR/USD and USD/CHF) tend to move in opposite directions.

The hidden risk

Opening trades on two strongly positively correlated pairs in the same direction is, in practice, similar to doubling the size of a single trade — if the move goes against you, both positions lose at the same time, even though it looks like two separate, diversified trades.

Why it matters for position sizing

Traders who aren’t aware of correlation can end up with much more risk concentrated in one underlying market move than their position sizing rules were designed to allow, simply by holding several correlated pairs at once.

Key takeaway

Before opening multiple positions, it’s worth checking whether the pairs are correlated — treating two highly correlated trades as independent risks is a common way traders unintentionally take on far more risk than planned.