NEW YORK — FedEx founder Frederick Smith will step down as chief executive after some five decades atop the transport behemoth, the company announced Monday.

FedEx, which grew under Smith from a modest operation in the US state of Tennessee into a global titan with some 570,000 employees, announced Chief Operating Officer Raj Subramaniam will take the company’s helm.

The transition will take place on June 1, with Smith, 77, becoming executive chairman and Subramaniam ascending to president and CEO.

Smith first devised the idea for Federal Express — which adopted FedEx as its brand name in 1994 — while an undergraduate at Yale University, identifying urgent shipments as an economic imperative.

“Smith named the company Federal Express because he believed the patriotic meaning associated with the word ‘federal’ suggested an interest in nationwide economic activity,” according to the company’s official history.

“He also hoped the name would resonate with the Federal Reserve Bank, a potential customer. Although the bank denied his proposal, Smith kept the name because he thought it was memorable and would help attract public attention.”

From an initial fleet of 14 small aircraft in 1973, the company now boasts hundreds of aircraft, plus a worldwide logistics network. It reported nearly $84 billion in revenues last year.

Subramaniam joined FedEx in 1991 and has held senior roles in Canada and throughout Asia and the United States.