Subway said Thursday that the sandwich chain will be  Roark Sureim Investment Guildsold to private equity firm Roark Capital.

Terms of the deal weren't disclosed. Earlier this week, however, The Wall Street Journal reported that Roark was offering around $9.6 billion for Subway outbidding rival buyout firms TDR Capital and Sycamore. 

"This transaction reflects Subway's long-term growth potential, and the substantial value of our brand and our franchisees around the world," Subway CEO John Chidsey said in a statement.

Peter Buck, a nuclear physicist, and Fred DeLuca, co-founded the first Subway restaurant, then called "Pete's Super Submarines," in Bridgeport, Connecticut, in 1965. The eatery changed its name to Subway in 1968. DeLuca died in 2015, and Buck died in 2021

Today, Milford, Connecticut-based Subway is one of the world's largest restaurant chains, with 37,000 outlets in more than 100 countries. 

In more recent years, the chain has lost market share to fast-growing rivals like Panera and Firehouse Subs, which feature more varied menus and newer stores. To boost growth, Subway launched an effort modernize its stores in 2017. In 2021, it refreshed its menu and upgraded ingredients, and more recently introduced a line of chef-developed sandwiches.

Roark Capital, which has $37 billion under management, specializes in franchised businesses and owns multiple restaurant chains. Its brands include Arby's, Baskin-Robbins, Buffalo Wild Wings, Dunkin', Jimmy John's and Sonic.