Interbrew was a large Belgium-based brewing company which owned many internationally known beers, as well as some smaller local beers. In 2004 Interbrew merged with Brazilian brewer AmBev to form InBev, which is the now largest brewer in the world by volume, with a 13% global market share (as of 2004).
Some important Interbrew brands are Stella Artois, Boddingtons, Beck's, Staropramen, Bass, Leffe, Labatt and Hoegaarden. Before the merger with Ambev, Interbrew was the third largest brewing company in the world by volume, Anheuser-Busch was the largest, followed by SABMiller in second place. Heineken International was in fourth place and AmBev was the world's fifth largest brewer.
Having its roots in Leuven, Interbrew was formed when the Flemish brewers of Stella Artois merged with Walloon-based brewer Piedboeuf. The move onto the international scene only happened when Interbrew acquired the Canadian beer brand Labatt. The transaction also included Labatt's assets, which included the Toronto Blue Jays baseball club, the Toronto Argonauts football club, and The Sports Network (the latter being immediately resold to NetStar Communications due to Canadian media ownership regulations). The latter at the time was not much smaller than Interbrew, and since then the company had been considered a multinational with both Canadian and Belgian roots.
Sources of Information
-  Wikipedia