The Federal Trade Commission (FTC) has filed a lawsuit against Zillow and its rival Redfin, alleging that the two companies engaged in an illegal agreement to suppress competition in the rental advertising market. The FTC claims that Zillow paid Redfin $100 million to prevent competition on online rental listings. This lawsuit comes amid concerns over antitrust violations and the impacts of such deals on market competition. As a result of the announcement, both Zillow and Rocket Companies, which owns Redfin, saw their stock prices decline significantly.