The U.S. Federal Trade Commission sued PepsiCo on Friday for offering preferential pricing to a large retailer, whom a source familiar with the matter confirmed was Walmart .

The Robinson-Patman Act was passed in 1936, but the federal government stopped enforcing it during the deregulation of the 1980s. The FTC resumed its enforcement in December when it sued Southern Glazer’s, the largest U.S. distributor of wine and spirits.

Although there are millions of options to choose from, Americans have their preferred soda brands, with Coca-Cola, Dr. Pepper, and Pepsi being among the most popular in terms of generated revenue. Related: PepsiCo makes surprising move with irresistible snack food brand PepsiCo is an American multinational food,