Overlapping area represents the amount of risk that can be diversified away by holding PIMCO 1 5 Year US TIPS ETF and iShares TIPS Bond ETF in the same portfolio assuming nothing else is changed. The correlation between historical prices or returns on iShares TIPS Bond and PIMCO 1 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 PIMCO 1 5 Year US TIPS ETF are associated (or correlated) with iShares TIPS. Values of the correlation coefficient range from -1 to +1, where. The correlation of zero (0) is possible when the price movement of iShares TIPS Bond has no effect on the direction of PIMCO 1 i.e. PIMCO 1 and iShares TIPS go up and down completely randomly.