"It's difficult to put into words the tremendous loss felt by all who knew Frederick W. Smith," FedEx CEO and President Raj Subramaniam said.

Fred Smith is of course a giant in the history of American business. His vision and daring revolutionized global commerce and connected the world in unprecedented ways. But to those who knew him, Fred was something even rarer: a leader whose values ran even deeper than his ambition.

Overseeing a fleet of cargo planes from his headquarters in Memphis, he transformed package delivery by promising overnight shipments.