Investors and bankers are drooling at the prospect of the biggest beer deal ever. Anheuser-Busch InBev, maker of Bud, said Wednesday that it’s talking with SABMiller about buying it.

Here’s why the world’s number one brewer wants to buy number two:

1) Scope: Buying SABMiller would give ABI new strength in international markets, particularly in Africa and Asia.

2) Scale: A bigger company could cut costs by driving a harder bargain with suppliers and saving money by combining production and distribution costs.

3) Pressure: Mass market beers are losing share to craft beer in America. Both companies are trying to play in the growing craft market, but the unimpressive performance of their core products is driving them to increasingly seek profits by cost-cutting and global growth.