This photo combo of file photos shows Bill Ackman, left, of Pershing Square Capital Management, on Feb. 6, 2012, in Toronto, and financier Carl Icahn, on Feb. 7, 2006, in New York. A

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This photo combo of file photos shows Bill Ackman, left, of Pershing Square Capital Management, on Feb. 6, 2012, in Toronto, and financier Carl Icahn, on Feb. 7, 2006, in New York. A long-simmering spat between billionaire investors Icahn and Ackman boiled over publicly on Friday, Jan. 25, 2013. The two Wall Street titans, interviewed by phone simultaneously on CNBC, traded barbs about an old investment deal and on Ackman’s investment position in nutritional supplements distributor Herbalife Inc. (AP Photo/Pawel Dwulit, Shiho Fukada) less