The Middle Class Is Steadily Eroding. Just Ask the Business World.

If there is any doubt, the speed at which companies are adapting to the new consumer landscape serves as very convincing evidence. Within top consulting firms and among Wall Street analysts, the shift is being described with a frankness more often associated with left-wing academics than business experts.

.. Even more striking, the current recovery has been driven almost entirely by the upper crust, according to Mr. Fazzari and Mr. Cynamon. Since 2009, the year the recession ended, inflation-adjusted spending by this top echelon has risen 17 percent, compared with just 1 percent among the bottom 95 percent.

.. Investors have taken notice of the shrinking middle. Shares of Sears and J. C. Penney have fallen more than 50 percent since the end of 2009, even as upper-end stores like Nordstrom and bargain-basement chains like Dollar Tree and Family Dollar Stores have more than doubled in value over the same period.