Cook's most likely successor is John Ternus, Apple's current senior vice president of hardware engineering. Ternus joined Apple in 2001, and at the age of 50, is one of the company's younger senior executives. Coincidentally, Cook was also 50 when he took over as the chief executive.

Apple CEO Tim Cook may step down from his role as early as next year, forcing the smartphone giant to step up its succession planning efforts, according to a new report by the Financial Times.