Currency correlation in forex explained
By Forexuro Desk. Education, not financial advice. All guides
Currency pairs do not move independently. Because every pair shares a currency with many others, and because the same forces drive several markets at once, some pairs tend to move together and others in opposite directions. This guide explains what correlation means, which relationships traders commonly watch, how correlation can quietly double your risk and how to keep it under control.
Free on Telegram. Follow Forexuro on Telegram for daily gold and forex market updates.
What correlation means
Correlation measures how closely two markets have moved together over a chosen period. It is usually expressed as a correlation coefficient between minus 1 and plus 1.
| Coefficient | Meaning |
|---|---|
| Close to plus 1 | The two markets have tended to move in the same direction |
| Around 0 | No consistent relationship over the period |
| Close to minus 1 | The two markets have tended to move in opposite directions |
The coefficient is normally calculated from percentage changes in price, such as daily returns, over a lookback window like 20, 50 or 100 periods. The result depends on the window and the timeframe you choose, so the same two pairs can look strongly linked on one view and weakly linked on another.
Why currency pairs are correlated
- Shared currencies. EUR/USD and GBP/USD both have the US dollar as the quote currency. Any broad move in the dollar pushes both pairs the same way.
- Inverted quotes. EUR/USD has the dollar second, USD/CHF has it first. A strong dollar pushes EUR/USD down and USD/CHF up, so they often move in opposite directions.
- Similar economies. The Australian and New Zealand dollars are both linked to commodity exports and Asian demand, so AUD/USD and NZD/USD often move together.
- Common drivers. Risk sentiment, interest rate expectations and commodity prices move several markets at the same time. Gold, for example, often moves opposite to the US dollar.
Commonly watched relationships
The table shows relationships that traders commonly monitor and the direction they have usually taken. These are tendencies, not fixed values: always check current figures over your own timeframe.
| Pair or market | Often compared with | Usual direction |
|---|---|---|
| EUR/USD | GBP/USD | Same direction |
| EUR/USD | USD/CHF | Opposite direction |
| AUD/USD | NZD/USD | Same direction |
| USD/CAD | Crude oil | Often opposite, as oil supports the Canadian dollar |
| Gold (XAU/USD) | US Dollar Index | Often opposite |
The hidden risk: doubling up without noticing
Correlation matters most for risk. Suppose you risk 1% of your account on a buy of EUR/USD and another 1% on a buy of GBP/USD. On paper you have two trades risking 1% each. In practice both trades are largely a bet against the US dollar. If the dollar strengthens sharply, both are likely to hit their stops together, and your real risk is close to 2% on a single idea.
The same happens in reverse. Buying EUR/USD and selling USD/CHF looks like two different trades, but both gain when the dollar weakens and both lose when it strengthens.
| Positions | Looks like | Is really closer to |
|---|---|---|
| Buy EUR/USD and buy GBP/USD, 1% risk each | Two separate trades | About 2% risk on a weaker dollar |
| Buy EUR/USD and sell USD/CHF, 1% risk each | Two separate trades | About 2% risk on a weaker dollar |
| Buy EUR/USD and sell GBP/USD, 1% risk each | Twice the exposure | Largely offsetting dollar exposure; mainly a view on EUR against GBP |
Our risk management guide explains risk per trade, and the lot size calculator helps you size each position. Correlation is the extra step of asking what your positions add up to.
Correlations change
Relationships between markets shift over time. A link that was strong for months can weaken when the main driver changes, for example when news specific to the UK dominates the pound, or when a central bank surprises. Periods of market stress can also push many assets to move together. Treat any correlation as a recent tendency and recheck it regularly rather than assuming it is permanent.
How to manage correlation in practice
- Before opening a new trade, list your open positions and the currencies they contain.
- Count your total exposure to each currency, not just the number of trades.
- Set a maximum combined risk for positions that depend on the same currency or theme.
- If two candidate trades are strongly correlated, take the one you prefer, or split your usual risk between them.
- Recheck correlations over your own timeframe from time to time, because they drift.
Using correlation as information
Correlation is not only a risk to manage. It can also add context to your analysis. If EUR/USD breaks higher but GBP/USD, AUD/USD and gold show no sign of a weaker dollar, the move may be driven by the euro alone rather than by broad dollar selling. That does not make the move wrong, but it tells you what is really behind it and which news is likely to matter most.
Some traders also compare a currency against several others at once. If the yen is falling against every major currency, the driver is probably in Japan. If only one yen pair is moving, the story is more likely to be about the other currency. This kind of cross checking is quick, needs no special software and helps you avoid treating a single chart in isolation.
A worked example
Your rules allow a maximum of 1% risk per trade and 2% combined risk on any one currency. You already hold a buy of EUR/USD risking 1%. A second idea appears: buy AUD/USD. Both trades gain if the dollar weakens, so together they would put 2% on a weaker dollar, which is your limit. A third idea, a sell of USD/JPY, would also gain from a weaker dollar, so under your rules you would skip it, or reduce the size of all three so the combined risk stays at 2%.
Correlation checklist
- I know which currencies my open positions share.
- I count combined risk on the same currency, not just trade by trade.
- I know that EUR/USD and USD/CHF often move in opposite directions.
- I treat correlations as tendencies that can change.
- I have a maximum combined risk for related positions.
Frequently asked questions
What is a good correlation to watch for?
Coefficients close to plus 1 or minus 1 indicate a strong relationship. Readings near 0 indicate little consistent relationship over the chosen period.
Are EUR/USD and GBP/USD correlated?
They have usually moved in the same direction, because both are quoted against the US dollar. The strength of the link changes over time, so check it over your own timeframe.
How does correlation affect risk?
Two trades on strongly correlated pairs behave much like one larger trade. Risking 1% on each can mean close to 2% on a single idea.
Related reads
Next guide: Trading rules and a trading journal
What to write in your rules, what to record and how to measure results in R.
Free, opens Telegram