There are nearly 9,000 breweries across the United States — 8,800 as of 2021 — yet the vast majority of the beer sold in U.S. grocery stores comes from a small handful of companies.

According to a recent study from The Guardian, as much as 78.6 percent of the beer sold at grocery stores is produced and owned by four major alcohol conglomerates.

Guardian’s internal assessment found that Anheuser-Busch InBev makes up 42 percent of the market, with brands like Budweiser, Bud Light, Stella Artois, and Goose Island.

The second leading firm is Molson Coors (24 percent), followed by Constellation Brands (9 percent), and finally Heineken (4 percent).

Numerous sources told the Guardian that complex distribution laws, and the close ties between major producers and beer distributors, were the reason for this market dominance.

“It’s challenging for a lot of small brewers to get access to the market when there’s this choke point, when your only option is to go with a distributor that already has 2,000 brands,” Bart Watson, chief economist for the Brewers Association, told The Guardian. “It makes it difficult for small breweries to grow. When you control the taps, you can control your own destiny. But it’s difficult to scale up.”