Correlation And Forex Investments

Correlation describes how two investments’ returns have moved in relation to each other. It is one of the concepts investors weigh when thinking about how the pieces of a portfolio fit together, and it is worth understanding before reading any claim about diversification. This article is educational only; it is not investment advice, and nothing here is a recommendation of any investment or portfolio.

Correlation is summarized by the correlation coefficient, a number that always falls between -1.0 and +1.0, calculated from the returns of two investments over a chosen period. A positive coefficient means the two tended to move in the same direction over that period; a negative coefficient means they tended to move in opposite directions; a coefficient near zero means the measurements show little consistent relationship in either direction.

The word tended is doing important work in each of those readings. A correlation is a summary of tendency across many observations, not a rule about individual moves. A negative coefficient does not mean that every time one investment rises the other falls, and a positive one does not mean the two always rise together. Strength matters too: values near the extremes describe a strong tendency, while values near zero describe a weak one.

Three cautions keep the number honest. First, correlation is historical and period-specific: it is computed from returns over one particular window, at one particular frequency, and a different window or frequency can produce a different figure. Second, a measured correlation of zero is not a promise of independence; it means no consistent linear relationship appeared in that sample, which does not assure the two investments will behave independently in the future. Third, relationships between markets can change, and correlations measured in calm periods may not hold in stressed ones.

For those reasons, there is no universally ideal correlation target for a portfolio, and no category of investment can be assumed to carry a particular correlation. Whether any Forex fund or account is weakly or strongly correlated with anything else is a question about its actual measured returns over a stated period, not about its label. How correlation figures into diversification depends on the portfolio’s actual positions, their concentrations, and the strategy pursued, and diversification itself does not assure a profit or protect against loss.

Whether any of this matters for a particular portfolio is a judgment each investor must make independently, ideally with a qualified professional. Trading foreign exchange involves substantial risk of loss and is not suitable for every investor.

Related articles on this site cover the Forex market, alternative investments, the Sharpe ratio, managed accounts and hedge funds, and how to evaluate a manager’s track record.