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