Overlapping area represents the amount of risk that can be diversified away by holding IPC and DOW in the same portfolio assuming nothing else is changed. The correlation between historical prices or returns on DOW and IPC 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 IPC are associated (or correlated) with DOW. Values of the correlation coefficient range from -1 to +1, where. The correlation of zero (0) is possible when the price movement of DOW has no effect on the direction of IPC i.e. IPC and DOW go up and down completely randomly.