The Justice Department is expanding its antitrust investigation into the U.S. beef industry to include eight major grocery chains, seeking information about whether retailers have engaged in price manipulation as beef prices reach record levels.

The DOJ announced Tuesday that it sent letters to Kroger, Publix, Walmart, Albertsons, Aldi, Ahold Delhaize USA, Costco, and Amazon seeking data on beef sales, pricing, costs, margins, and purchasing practices.