The corporate headquarters of the new company will be in Canada. The two brands will continue to be run as stand-alone chains, with Burger King still operating out of Miami.
Some analysts have suggested that Canada's lower tax rates stand to benefit Burger King over time. But Burger King said that's the not main motivation for the deal.
During a conference call with analysts and investors, Burger King Executive Chairman Alex Behring stressed that international growth possibilities are driving the deal. He noted that 3G Capital, the investment firm that owns a majority stake in Burger King, has turned the hamburger company into one of the fastest-growing chains since buying it in 2010. He said that experience will be applied to Tim Hortons.
"It's not being driven by tax rates," Behring said.
In recent years, more U.S. companies have acquired businesses in countries with lower tax rates, then moved their headquarters there. Such tax inversions have become the subject of criticism by President Barack Obama and Congress because they mean the loss of revenue for the U.S. government.
After the deal, which is expected to close by early next year, the new company would have about $23 billion in sales and more than 18,000 locations.
The tie-up could help Burger King and Tim Hortons pose a greater challenge to market leaders such as McDonald's and Starbucks and reflects a desire by both companies to expand internationally. Burger King, which has nearly 14,000 locations, has been striking deals to open more locations in developing markets. The company sees plenty of room for growth internationally, given the more than 35,000 locations McDonald's has around the world. Tim Hortons has more than 4,500 locations, mostly in Canada.
Back in the U.S., breakfast and coffee have been hot growth areas in the fast-food industry. Between 2007 and 2012, breakfast grew faster than any other segment in the restaurant industry at about 5 percent a year, according to market researcher Technomic. But it has long remained a weak spot for Burger King.
3G Capital will own about 51 percent of the new company. The firm, which has offices in Brazil and New York, has been slashing costs at Burger King since buying it in 2010. Last year, 3G teamed up with Warren Buffett's Berkshire Hathaway to buy ketchup maker Heinz as well.
Berkshire Hathaway is also helping finance the Tim Hortons deal with $3 billion of preferred equity financing, but will not have a role in managing operations.
Under the deal, Burger King will pay $65.50 Canadian ($59.74) in cash and 0.8025 common shares of the new company for each Tim Hortons share. This represents total value per Tim Hortons share of $94.05 Canadian (US$85.79), based on Burger King's Monday closing stock price. Alternatively, Tim Hortons shareholders may choose either all-cash or all stock in the new company.
Tim Hortons stock rose more than 10 percent in Tuesday premarket trading. Burger King's shares fell slightly.