For many in the real estate industry, Zillow’s announcement that it had filed an antitrust lawsuit against Midwest Real Estate Data (MRED) and Compass International Holdings earlier this month came with a sense of deja vu.
Bradley Weber, the co-chair of Troutman Pepper Locke’s antitrust practice group, views the allegations made by Zillow as the “mirror image” of the claims Compass made in its antitrust lawsuit filed against Zillow last June, which it voluntarily dismissed in March 2026.
“It is striking that the claims Zillow is now making against Compass are basically the same claims Compass was making against Zillow under Section 1 of the Sherman Act for conspiracy and Section 2 for monopolizing a relevant market,” he said.
In the suit, Zillow claims that Compass and MRED are taking part in a horizontal group boycott, which Weber said would imply, under a per se application of the law, that the two defendants are competitors.
“There is a theory there that Compass is competing with MRED because it has its own private listing service, but I am not sure how strong of an argument that is,” Weber said.
In addition, Zillow also makes a vertical conspiracy claim against MRED and Compass, which Weber said would fall under the rule of reason application of the law. He feels this argument may be stronger, especially when it comes to Zillow’s claim of monopoly power.
“If these vertical agreements are designed to enhance or protect large market share, which in MRED’s case is the vast majority of the MLS listing in Chicagoland,” he said. “So, if by entering into this relationship with Compass, it is protecting MRED from competition, then that could be a viable claim.”
As Chuck Cain, an attorney and the president of Alliance Solutions, sees the question at the center of the lawsuit as “can companies that have data, which they view as proprietary, have exclusive control of that data, or, especially in the world of realty post Sitzer/Burnett, if companies the size of the defendants withhold that data from the MLS, is it an antitrust violation?”
“That is the real question and I have no idea how the courts will look at this,” Cain said.
As with any antitrust lawsuit, the impact on consumers is front and center here, and for Cain that opens the door for even more questions to surface over the course of this litigation.
“The defense’s position is that consumers are not harmed by withholding listings from Zillow, they just need to go to our website, which is three clicks away,” Cain said. “But does that then cause confusion for the consumer? And if it devolves to consumers needing to go to 20 websites to see what is actually for sale in a neighborhood, are aggregators entitled to access that data or is the data proprietary?”
Is Zillow now a public utility?
As for Zillow, Cain believes the court will have to examine whether Zillow “is so large and relied on by so many consumers nationwide, that cutting off listing data to it causes consumer harm?”
“This then begs the question, is Zillow a public utility? Is it so large and has been around for so many years that it has become effectively some sort of public utility? I don’t think that is what Zillow wants to see or hear, but that is how this could go,” Cain added.
Although it remains to be seen which questions the lawsuit will actually attempt to answer, attorneys agree that Zillow may be using this litigation as a “warning shot.”
“I think one of Zillow’s primary goals with this lawsuit is to scare other MLSs so they don’t follow MRED’s lead,” Harrison McAvoy, a partner at Mandelbaum Barrett PC, said. “They want to show the MLSs that there is something to be afraid of if they pull their listing feed from Zillow.”
Weber agrees, as he feels this might be Zillow’s way of telling other MLSs that if they follow MRED’s suit, they might be opening themselves up to a costly federal lawsuit.
“For PR reasons, I could see why Zillow would file this to sort of scare off other MLSs from entering into similar agreements with Compass,” Weber said.
In McAvoy’s view, however, MRED and Compass ultimately have the better of the two arguments on the merits of the case, due to the fact that Zillow’s listing access standards policy, reflects, in his mind, an exercise of market power and restriction on competition, by forcing sellers to market their properties in a certain way.
Outcome could reshape things more than Sitzer/Burnett
But whichever way the case shakes out, the attorneys agree that the outcome could have a massive impact on the real estate industry.
“I think this litigation has the potential to be an even bigger decision than Sitzer/Burnett and the suits that followed with how it could potentially reshape things. Both sides are trying to throw the table over and however this comes out, it is pretty much how things will operate moving forward and it could have major implications for the industry, especially if the defendants prevail,” Cain said.
If Compass and MRED win the lawsuit, Weber feels that the MLS-broker relationship model being established by the defendants would become more prevalent.
“This would definitely threaten Zillow’s market position and it would show that you don’t have to follow Zillow’s rules, which historically, is what much of the industry has done because they have become reliant on Zillow for leads and services,” Weber said.
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