Co-founder and a managing director of Chieftain Capital Management in Manhattan, he graduated from Yale and has two master's degrees, one in literature from New York University and another in business administration from Columbia. His mother is an art collector and a daughter of the late Bernard F. Gimbel, a chairman of Gimbel Brothers, the department store chain. His father played first base for the Detroit Tigers and the Pittsburgh Pirates, and was elected to the Baseball Hall of Fame in 1956. He is a stepson of Joseph Lebworth. Mr. Greenberg, a former competitive squash player, founded Chieftain with John Shapiro in 1984. In 2009 Mr. Shapiro and Chieftain partners Tom Stern and Joshua Slocum launched a new investment firm that will retain the name Chieftain Capital Management. Chieftain manages about $3 billion in assets. Messrs. Shapiro and Stern are cousins. Mr. Greenberg's firm will be renamed Brave Warrior Advisors.