Southern Glazer’s Wine and Spirits, the United States’ largest distributor of wine and spirits, faces a lawsuit from the Federal Trade Commission for alleged price discrimination.

The FTC accused the company of giving large discount chains such as Costco and Walmart price breaks while charging small independent stores a higher price. Federal officials say that Southern Glazer’s violated the Robinson-Patman Act. The FTC says that the act prohibits companies from giving their favored customers an unfair advantage in the market.