A negative correlation between two stocks typically exists for fundamental reasons, such as different sensitivities to interest rate changes. Entire asset classes, e.g., stocks and bonds, can be ...

This graph plots the correlation between people who died by falling out of wheelchairs between 1999 and 2005, and the rising costs of a 16oz bag of potato chips in the U.S during the same period.

Figure 6 indicates the historical positive correlation to a diversified portfolio of +0.2 when it is increasing and a negative correlation of -0.2 when it is decreasing.