“Kimmo Soramäki has seen something strange happening in U.S. house prices. The math behind his findings is fiendishly complex, but he can show the results to anyone in seconds.
Mr. Soramäki is a specialist in a kind of financial mapmaking: He takes a complex analysis of the relations between financial institutions or markets, and by weeding out some information and focusing on the most significant links, he can create simple treelike images that reveal something—in this case, that housing prices have become increasingly correlated”.