Correlation Doesn’t Tell the Whole Story

January 13, 2012 | Tom Salemy, CFA, CAIA, Partner

This week’s Chart of the Week covers increased correlations among asset classes. Correlation is a statistical measure showing how two variables move in relation to each other. It can range anywhere from -1 to1, and refers only to the direction of changes. Perfect negative correlation (-1), implies that two items move in completely opposite directions and perfect positive correlation (+1), implies that two items move in lock-step. The chart above shows the five-year correlations between the S&P 500 and a broad set of sample asset classes. As evident, all risk-assets have had a very high positive correlation to the S&P 500 over the past five years. Referring to the chart, aside from the three Treasury indices, no other asset class has a correlation less than .90, which is extremely high.

However, correlation only tells part of the story: just because two asset classes have high correlation does not mean that their returns will end up being the same. In fact, this will most likely never be the case. For example, over the time-frame captured above, despite very high correlations, emerging markets, the S&P 500, and the REIT index have annualized returns of 2.8%, -.56% and -3.48% respectively. Over the past five years, as globalization has become more pronounced and economies more intertwined, correlations have certainly increased to all time high levels. But since correlation does not capture magnitude of returns, investors should continue to utilize an asset allocation model that takes potential risk and return into account.