MONTREAL -- Molson Coors will nearly double its size once it completes a US$12-billion purchase that secures full ownership of its U.S. beer business and gains worldwide control of the Miller brand name.

Mark Hunter, the CEO for Molson Coors, said the "game-changing" transaction to acquire full ownership of Miller Coors -- a partnership with SABMiller -- will allow the company to invest more in its brands and increase consumer choice.

"This is a compelling strategic and financial opportunity that catapults Molson Coors to the next level," Hunter said Wednesday during a conference call, noting it will add US$4.7 billion in annual revenues and more than US$1 billion in earnings.

"It creates a leading North American brewer with a unique portfolio of iconic brands. This is a rapidly evolving industry and this transaction gives us opportunity to materially strengthen our U.S. business."

Canada's share of total Molson Coors revenue will drop to 15 per cent, from 24 per cent, while the U.S. share will grow by 20 percentage points to 64 per cent, industry observers say.

The Molson Coors purchase of SABMiller's 58 per cent stake in a U.S. joint venture, formed in 2008, is separate but related to an even bigger deal that will combine the world's two biggest brewing companies.

SABMiller has agreed to a US$107-billion takeover by industry leader Anheuser-Busch InBev, maker of Budweiser beers, and agreed to sell its share of Miller Coors to reduce regulatory concern that one company would control the U.S. market.

Molson Coors is also buying the global rights to the Miller brand, giving the company greater access to established markets in Canada and Britain, emerging high growth markets like Panama and new countries such as Argentina.

The transaction effectively reverses last year's termination of a longstanding agreement to distribute Miller products in Canada, and also gives Molson Coors full control on how to produce, market and sell those brands. Canada is part of the US$70 million in earnings and US$200 million in annual revenues the Miller international brands outside the U.S.

In Canada, the beer market has long been dominated by Molson Coors and AB InBev, through its ownership of Labatt, although the two beer giants have increasingly been challenged by the popularity of smaller local craft brewers.

In addition to the Miller brands, the deal gives Molson Coors perpetual royalty-free U.S. licences for SABMiller brands including Peroni, Pilsner Urquell, Foster's and Redd's.

Much of the deal's financial contribution is tied to US$250 million in tax benefits over 15 years and at least US$200 million in annual cost savings, although analysts expect cost savings could reach US$300 million to US$400 million.

Brittany Weissman of Edward Jones said the deal likely won't change much for Canadian consumers.

"Most of the way that that landscape changes is going to be behind the scenes in terms of cost savings," she said.

Molson Coors will become a stronger player to withstand further market consolidation or lead the acquisition of another brewer, she said.