The economist has a good article on this with a number of hypotheses: http://www.economist.com/blogs/buttonwood/2016/02/markets-and-economics http://www.economi

The economist has a good article on this with a number of hypotheses: http://www.economist.com/blogs/buttonwood/2016/02/markets-and-economics http://www.economist.com/blogs/buttonwood/2016/02/markets-an...