ITV plc, the U.K.’s biggest commercial broadcaster, agreed to acquire a controlling stake in Leftfield Entertainment Group for $360 million to become the largest unscripted independent producer in the U.S.

ITV, whose shows include “X Factor” and “Downton Abbey,” will pay the amount in cash for an 80 percent stake in Leftfield, the London-based broadcaster said in a statement today. The acquisition, which will add to earnings immediately, has gained regulatory approval, ITV said.

Leftfield, an independent producer of reality programs, has made TV hits including “Pawn Stars” for The History Channel and “The Real Housewives of New Jersey” for the Bravo network. ITV has been expanding its U.S.-production business with acquisitions in recent years of High Noon Entertainment, Thinkfactory Media and DiGa Vision, which produce shows such as “Cake Boss,” “Teen Wolf” and “Hatfields & McCoys.”

“The acquisition of the Leftfield Group represents a significant addition to ITV Studios as we continue to build our global content business over the long term,” ITV Chief Executive Officer Adam Crozier said in today’s statement.

ITV shares rose 1.5 percent to 188.6 pence as of 9:02 a.m. in London trading, giving the company a market value of 7.6 billion pounds ($12.9 billion).

ITV has an option to buy the remaining 20 percent of Leftfield after three years and the maximum consideration for the entire company is $800 million, including the initial payment.

Sirens Media

Leftfield Entertainment was formed in 2013 when Leftfield Pictures bought Sirens Media, and it has established two joint ventures, with the businesses producing more than 300 hours of unscripted programming.

The deal for Leftfield is “a big strategic positive,” Ian Whittaker, a media analyst at Liberum Capital in London, wrote in a note. “It makes ITV an even more serious player in the U.S. reality market” with shows that can be copied in overseas markets and add to ITV’s global content business.

ITV has been reducing its dependence on advertising by investing in content creation and by acquiring production assets under CEO Crozier, the former head of Royal Mail Group Plc who took over in 2010.

Leftfield had $38 million earnings before interest, tax, depreciation and amortization on a pro-forma basis in 2013 and ITV predicted it will continue to deliver strong growth at a high margin into 2014 and beyond.

ITV competes with international production companies including FremantleMedia SA, Endemol NV and All3Media International Ltd.