Per Krusell (from left), Staffan Normark, Peter Gardenfors and Tore Ellingsen of the Swedish Royal Academy of Sciences announce the winners of the Nobel Memorial Prize in Economic Sciences in Stockholm on Monday, Oct. 15, 2012. Americans Alvin Roth of Harvard University and Lloyd Shapley of the University of California at Los Angeles were cited for "the theory of stable allocations and the practice of market design." (AP Photo/Scanpix Sweden, Henrik Montgomery)

Photo by: Henrik Montgomery

Per Krusell (from left), Staffan Normark, Peter Gardenfors and Tore Ellingsen of the Swedish Royal Academy of Sciences announce the winners of the Nobel Memorial Prize in Economic Sciences in Stockholm on Monday, Oct. 15, 2012. Americans Alvin Roth of Harvard University and Lloyd Shapley of the University of California at Los Angeles were cited for "the theory of stable allocations and the practice of market design." (AP Photo/Scanpix Sweden, Henrik Montgomery)