(Reuters) -Cushman & Wakefield ( CWK ) was among six large landlords sued by the U.S. Department of Justice over alleged anticompetitive practices in housing rental markets, the DOJ said on Tuesday.

The companies were added to the DOJ's lawsuit in North Carolina accusing property management software company RealPage of letting landlords collude by sharing their pricing information with the company's software, which then recommends rent prices.

RealPage has denied the allegations.

Greystar Real Estate Partners, Blackstone's LivCor, Camden Property Trust ( CPT ), Pinnacle Property Management Services and Willow Bridge Property Co. were also named in the lawsuit. Cortland Management has agreed to settle the claims, the DOJ said.