The US Federal Trade Commission (FTC) has launched legal action against PepsiCo, accusing the company of engaging in “illegal price discrimination” within soft drinks. The first of two key inflation reports this week showed wholesale prices increased less than expected in December.

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,

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.

Outgoing agency Chair Lina Khan has filed a raft of measures during her last week in office.

The agency claims the soda giant gave “unfair” pricing advantages to a larger retailer, forcing consumers to pay more at competing stores. Pepsi “strongly disputes” the allegations.

The commission alleges that the retailer, whose name was redacted in the statement from commissioners, received “unfair pricing advantages” that were not made available to others.