Overlapping area represents the amount of risk that can be diversified away by holding Macys Inc and Visa Inc in the same portfolio assuming nothing else is changed. The correlation between historical prices or returns on Visa and Macys is a relative statistical measure of the degree to which these equity instruments tend to move together. The correlation coefficient measures the extent to which returns on Macys are associated (or correlated) with Visa. Values of the correlation coefficient range from -1 to +1, where. The correlation of zero (0) is possible when the price movement of Visa has no effect on the direction of Macys i.e. Macys and Visa go up and down completely randomly.