New York-based Blackstone Group said it was acquiring Antares Restaurant Group, which operates Burger King stores in New Zealand.
Antares was previously owned by Australasian private equity fund Anchorage Capital Partners.
The purchase price was not disclosed.
Described as one of the "barbarians" of private equity, Blackstone was formed in 1985 and was the first firm of its kind to publicly list on the New York Stock Exchange in 2007. It manages assets worth US$150 billion ($NZ186 billion) and has a reputation for making record-breaking buyouts.
Co-founder, chairman and chief executive Stephen Schwarzman has said he wanted to "inflict pain" on and "kill off" his rivals when chasing a deal.
Blackstone said yesterday it would continue Antares' refurbishment of local Burger King restaurants and also planned to add new branches.
Senior managing director Peter Rose could not give specifics of the expansion but said the company was "very optimistic and very encouraged" by the possibilities for growth.
Although this is believed to be Blackstone's first involvement with Burger King, Mr Rose said the group had experience owning and operating food businesses in Britain.
Speaking from New York, Mr Rose said Blackstone was drawn to Antares' "world-class" management team.
"Burger King is an iconic franchise and obviously world-renowned, but as with all retail and personal-services businesses, management is the key, and with the management here we saw just a world-class team," he said.
Antares' management team would stay on.
Antares chief executive John Elliott said Blackstone "was the perfect partner" to take the company to the next level.
Anchorage Capital partner Mark Bayliss said Antares was sold because the private equity fund had "done its bit" and breathed new life into the firm.
"[Anchorage] turns around underperforming businesses, when we've put businesses on a sustainable growth platform we hand it on to someone who can take it through a growth phase. We bought an inherently good business, changed some of the management team and we've transformed every single aspect of the business, financially, operationally and strategically," Mr Bayliss said.
