Correlation Risk

Correlation risk is the danger that positions which look separate on your trading platform are, in reality, driven by the same underlying factor and therefore move together. Two assets are positively correlated when they tend to rise and fall at the same time, and negatively correlated when one tends to rise as the other falls. Ignoring these relationships is one of the most common ways traders end up with far more risk than they think they've taken on.

A classic forex example: a trader goes long EURUSD, long GBPUSD, and long AUDUSD, each sized at 1% risk, believing they've spread their exposure across three trades. In practice, all three pairs share the US dollar on the other side, so this is closer to one large bet against the dollar than three independent ones. If the dollar strengthens broadly, all three positions lose at the same time, and the real drawdown is much closer to 3% than the 1% any single trade suggested.

This is what makes correlation risk dangerous — it hides inside position sizing that looks disciplined on paper. Each trade individually respects the rules, but the combined exposure to a single driver multiplies the actual risk taken far beyond what the trader intended or budgeted for.

Managing it starts with knowing which instruments in your trading universe tend to move together, using a correlation matrix if one is available. From there, treat correlated positions as a single combined risk allocation rather than several separate ones, and consciously limit how many correlated trades you hold open at the same time.