The FTC is suing Zillow and Redfin, alleging the companies struck an illegal deal to suppress competition in online rental advertising.

The lawsuit claims Zillow paid Redfin $100 million in exchange for ending contracts with other advertising partners, halting competing ads for multifamily properties for up to nine years, and syndicating Zillow listings on Redfin’s platforms.

The FTC argues the deal reduces competition, raises advertising costs, and harms renters and property managers.

Zillow and Redfin deny wrongdoing, calling the partnership pro-competitive and beneficial for users, The Guardian has reported.

The FTC seeks to end the agreement and may pursue remedies such as asset divestiture or business restructuring.