Sign up for The Big Story newsletter to receive stories like this one in your inbox.Renters filed a lawsuit this week alleging that a company that makes price-setting software for apartments and nine of the nation’s biggest property managers formed a cartel to artificially inflate rents in violation of federal law.The lawsuit was filed days after ProPublica published an investigation raising concerns that the software, sold by Texas-based RealPage, is potentially pushing rent prices above competitive levels, facilitating price-fixing, or both.The lawsuit accused the property managers and RealPage of forming “a cartel to artificially inflate the price of and artificially decrease the supply and output of multifamily residential real estate leases from competitive levels.”RealPage’s software uses an algorithm to churn through a trove of data each night to suggest daily prices for available rental units.The software considers actual rents paid to those rivals—not just what they are advertising, the company told ProPublica."