Zillow and Redfin, the two largest American real estate listing platforms, reached a settlement with the Federal Trade Commission and five states - on the very morning the case was due to go to trial. The timing is no accident: a settlement gets signed when somebody has calculated that the courtroom costs more.

The dispute concerns a deal from last year under which Redfin agreed to display rental listings from Zillow instead of competing with it for advertisers. The arrangement could have kept Redfin out of that business for up to nine years. Redfin owns Rent.com and ApartmentGuide.com - two of the larger rental platforms in the US.

According to the regulator and prosecutors from Arizona, Connecticut, New York, Virginia and Washington, the matter has a much simpler name. Zillow agreed to pay Redfin 100 million dollars to stop competing with it.

The companies defended the deal by saying it gives renters access to a wider selection of listings. The Commission argued something else: that Zillow is paying one of its largest competitors to step out of the way, letting it charge higher prices and offer worse terms to building managers.

Note how cleanly the accusation is stated. This is not a hidden algorithm or an intricate scheme - one company pays another not to work. That is competition bought wholesale, with an invoice.

Under the settlement, Redfin must return to the rental advertising business. The restrictions that stopped it from competing independently for clients among property managers are lifted. It can sell ads, display listings from its own clients and seek new ones - with no obligation to share sensitive data with Zillow. The link to Zillow is not severed entirely: Zillow's listings will continue to appear on Redfin.

The case comes a few months after the US Justice Department's settlement with Ticketmaster, in a similar dispute over a company using its size to smother competition. With one difference worth remembering: 26 of the 30 state prosecutors who set out alongside the department decided not to sign, carried on alone and won their case in April.

That is exactly the part that rarely reaches the headlines. When the central regulator sits down to settle, the case does not have to end - if one of the smaller players has the patience to carry it further. The question for the US rental market stays open: will Redfin's return genuinely bring prices down, or only restore the appearance of a competition that was already sold once for 100 million.