If you rent your home, there's a good chance your landlord uses RealPage to set your monthly payment. The company describes itself as merely helping landlords set the most profitable price. But a series of lawsuits says it's something else: an AI-enabled price-fixing conspiracy. The late Justice Antonin Scalia once called price-fixing the "supreme evil" of antitrust law. Agreeing to fix prices is punishable with up to 10 years in prison and a $100 million fine. Property owners feed RealPage's "property management software" their data, including unit prices and vacancy rates, and the algorithmwhich also knows what competitors are charging"spits out a rent recommendation. If enough landlords use it, the result could look the same as a traditional price-fixing cartel: lockstep price increases instead of price competition, no secret handshake or clandestine meeting needed. Algorithmic price-fixing appears to be spreading to more and more industries. And existing laws may not be equipped to stop it. In more than 40 housing markets across the United States, 30 to 60 percent of multifamily-building units are priced using RealPage. The plaintiffs suing RealPage, including the Arizona and Washington, D.C., attorneys general, argue that this has enabled a critical mass of landlords to raise rents in concert, making an existing housing-affordability crisis even worse. The lawsuits also argue that RealPage pressures landlords to comply with its pricing suggestions.