Peter Buck, Subway co-founder, dies at 90

Peter Buck, a nuclear physicist whose $1,000 investment in the first Subway sandwich shop more than 50 years ago eventually turned him into a billionaire, has died at age 90. 

It was Buck who inspired Fred DeLuca, then a 17-year-old college freshman, to start a submarine sandwich chain to help pay for tuition, according to a history of the company on its website. With Buck's modest backing, the two opened the first Subway restaurant, then called "Pete's Super Submarines," in Bridgeport, Connecticut, in 1965. Its priciest sandwich cost 69 cents. 

Three years later, the restaurant changed its name to Subway, and by 1973 Buck and DeLuca were operating 16 sandwich shops throughout the state. They soon decided to franchise the brand, and today the privately held company has more than 40,000 locations around the world.  

Buck died on Thursday, according to Subway. He is survived by two sons and five grandchildren. Forbes recently pegged Buck's wealth at $1.7 billion. 

"We are deeply saddened by the passing of one of Subway's founders, Dr. Peter Buck," Subway CEO John Chidsey said in a statement. "He was a shining example of a dedicated, hands-on leader, and an integral member of the Subway family. Dr. Buck's devotion to Subway, and his vision for the brand, helped grow it from a singular sandwich shop in Bridgeport, Connecticut, to the world's largest restaurant brand."  

Buck was born in South Portland, Maine, in 1930. He graduated from Bowdoin College in Brunswick, Maine, in 1952, and earned a master's degree and doctorate in physics at Columbia University. He later helped design nuclear submarines for the U.S. Navy and worked for General Electric, according to Bloomberg. 

Among his philanthropic activities, Buck held over 1.2 million acres of timberland under the Tall Timbers Trust, according to Subway.

DeLuca died in 2015 at age 67. At the time of his death, Forbes estimated his net worth at $3.5 billion. 

—The Associated Press contributed to this report.