The Department of Justice on Tuesday sued six of the nation’s largest landlords, accusing them of using a pricing algorithm to improperly work together to raise rents across the country. The lawsuit expands an antitrust complaint the department filed in August that accused property management software-maker RealPage of engaging in illegal price-fixing to reduce competition among landlords

The U.S. Justice Department is suing several large landlords for allegedly coordinating to keep Americans’ rents high.

The U.S. Department of Justice and 10 state attorneys general have ramped up their antitrust lawsuit against RealPage, a property management software compa