The correlation in global economic fundamentals is at a new high, reflected in the steadily increasing correlation in asset price movements. (bigpicture.typepad.com)
At the same time, many experts were claiming that the rise of passive investing was causing increased correlations in the stock market. (mindfullyinvesting.com)
Obviously more sophisticated methods could be used to determine the new series, which would increase the correlation further. (informath.org)