The cause was brain cancer, according to a statement from sports marketing giant IMG, where Forstmann served as chairman and CEO.
A pioneer of the buyout business, celebrity bachelor and free market proselytizer, Forstmann cut the figure of a swashbuckling risk taker. But in buying companies, he tended to be more careful and conservative than did rivals. Famously, he backed down from buying RJR Nabisco in the late 80s when the price got too high. His instincts turned out right. The winner, Kohlberg Kravis Roberts, struggled for years to wring profits from the company.
In 1988, Forstmann made clear his distaste for deal making greased by junk bonds. The AP quoted him as saying "Today's financial age has become a period of unbridled excess with accepted risk soaring out of proportion to possible reward."