FILE PHOTO: The U.S. Federal Trade Commission seal is seen at a news conference at FTC headquarters in Washington, U.S., July 24, 2019. REUTERS/Yuri Gripas/File Photo/File Photo

By Jody Godoy

(Reuters) -Zillow allegedly paid Redfin $100 million to stop competing against it in online apartment rental listings, the U.S. Federal Trade Commission said on Tuesday in a lawsuit against the online real estate platforms.

The agency said the alleged deal reduces competition in an already concentrated market and is likely to drive up the cost of advertising vacancies in rental buildings with more than 25 units. The deal also reduces the incentive for the companies to compete by making their sites easier for renters to use, the FTC said in the lawsuit filed in Alexandria, Virginia.

“Paying off a competitor to stop competing against you is a violation of federal antitrust laws,” said Daniel Guarnera, who leads the FTC’s Bureau of Competition.

The case targets a deal that happened in February, after President Donald Trump took office, showing the Republican-led agency is willing to take on big corporations over alleged violations. The FTC also sued Uber and Live Nation this year accusing them of violating consumer protection laws.

A Zillow spokesperson said the arrangement benefits renters and property managers.

"We remain confident in this partnership and the enhanced value it has delivered and will continue to deliver to consumers," the spokesperson said.

Zillow CEO Jeremy Wacksman said at the time that the deal, which includes an agreement for Redfin to display Zillow's listings on its site, would result in "more apartments available across more platforms."

Zillow runs listing sites Trulia, HotPads and StreetEasy, while Redfin operates Rent.com and ApartmentGuide.com.

A spokesperson for Redfin did not immediately reply to a request for comment on Tuesday.

Under the companies' agreement, the FTC said, Redfin transferred the bulk of its online apartment rentals business and agreed to stay out of the market for up to nine years. Redfin also agreed to help Zillow hire the sales force it fired, and to transition customers to Zillow's platform, the agency said.

Rocket Companies owns Redfin, having completed its acquisition of the company in July.

(Reporting by Christian Martinez and Jody Godoy in New York; Editing by Leslie Adler, Daniel Wallis and Franklin Paul)