The global beer industry is already dominated by a handful of large businesses, and, if corporate deal makers have their way, there will be even less competition. The industry’s second-biggest player, SABMiller, made a takeover offer for Heineken, the world’s third-largest brewer, which Heineken rejected last month. That news was quickly followed by reports that the beer industry’s leader, Anheuser-Busch InBev, was trying to get the financing to buy SABMiller. If that deal happens, about 30 percent of the global beer industry, which has annual sales of nearly $150 billion, would be controlled by one company.

Because of mergers in recent years, about three-quarters of the beer Americans drink is now sold by two companies: InBev and MillerCoors, a joint venture in which SABMiller owns a 58 percent stake. The industry is even more concentrated in countries like South Africa, Turkey and Brazil, where one of those two companies controls about 70 percent of beer sales, according to a recent report by Philip Howard of Michigan State University.

Consolidation on this scale leads to higher prices and fewer choices. Last year, the Justice Department’s Antitrust Division sued to block InBev’s proposed $20.1 billion takeover of a big Mexican brewer, Grupo Modelo, arguing that the merger would lead to price increases in the United States. (The case was settled when InBev agreed to sell Modelo’s American business.)

In addition to raising prices, the big brewers have used their clout to try to slow the growth of craft beer companies by offering distributors and retailers incentives not to carry smaller labels. While craft beers are growing fast — they were up 17.2 percent in 2013 even as total beer sales declined by almost 2 percent — smaller brewers account for just 7.8 percent of American beer sales. And many of them cannot easily expand because they are often at the mercy of large wholesalers who cater to the industry giants.