Suppose you have the data for the currency correlations of the major pairs. The correlation between GBP/USD and EUR/USD is 0.68. It means that both the pairs move in the same direction 68% of the time.

USD/CHF and EUR/USD have a correlation coefficient of -0.975. This is pretty close to (-1). It means both these pairs move in the opposite direction almost all the time. To be precise 97.5% of the time if USD/CHF moves up, the pair EUR/USD will move down!

You have this information. It tells you how much these pairs move in the same or opposite directions. Suppose you trade both the pairs USD/CHF and EUR/USD by going long at the same time. What you will be doing is in fact canceling both the positions.

If you win on USD/CHF pair, you will lose on EUR/USD pair. Due to the negative correlation between the two pairs, the two trades would effectively cancel each other. A savvy investor would go long on USD/CHF. At the same time he/she will go short on EUR/USD. So he/she will be shorting USD in both the trades and diversifying the USD bearish investment.

You can make trade entry and exit decisions based on currency correlations. Suppose GBP/USD starts showing volatility and approaches a resistance level. You anticipate going long on a breakout.

However, you notice that the other three pairs are not moving as much as the GBP/USD. EUR/USD is not moving up. USD/CHF is not moving down. USD/JPY is not moving down. This means that the move in GBP/USD is solely pound driven related to some news in the British economy.

You know now that the move in GBP/USD pair is GBP driven. The move is not US Dollar driven. You have isolated the cause of movement in GBP/USD pair and can take advantage of this information. Ignore the GBP driven move. Dont enter into any trade. Wait for a later opportunity. An opportunity that involves simultaneous correlated moves of all the major pairs!

Lets take another example. Suppose you have taken a short position on EUR/USD pair. You want to be sure whether the pair will proceed down towards your profit target. You also want to know can it go against you and cause you to exit the trade with a small loss.

Your EUR/USD is heading towards M1 level after having broken the S1 support pivot level. You should take a look at the pair EUR/GBP. You find that it has paused at its S1 support pivot level. It is showing signs of reversing to the upside.

In this type of a situation, knowledge of currency correlations can tell you if EUR/GBP breaks through the S1 level, you are poised for a profitable trade. However, if it reverses and heads back to the upside, you should watch the indicators and exit before taking a big loss. As you mature in forex trading, you might consider trading a basket of all the major currencies.