Zillow research released in May found that home sellers lost a combined $1.49 billion to same-agent dual agency and $1.36 billion to off-MLS listings between 2023 and 2025, based on an analysis of more than 15 million transactions.
Two sources with no role in the study—a Chicago broker/owner and a real estate economist—reviewed the findings and broke them down for RISMedia. Both said the direction of the results is right, but neither was 100% certain on the numbers.
The view from the ground
Cory Tanzer has been a broker in Chicago for 11 years and owns an independent brokerage with roughly 30 agents. He says the share of homes moving through private channels has climbed sharply in recent years.
“What I’ve noticed is—over the last couple of years—things never making it into the private listing network, going directly from somewhere into the MLS and closing on the same day,” Tanzer says.
The effect on his buyers, he says, is that homes surface only once they are already gone.
“They’re seeing a property hit the MLS on their search or on a portal website like Zillow, and they’re saying, ‘Hey, how come we didn’t see this?’ and ‘Why didn’t we see this before?’”
Asked whether Zillow’s finding—that off-MLS sellers typically netted 1.3% less than comparable sellers who listed publicly—matched his experience, Tanzer says it did not go far enough.
“I think that number is low from Zillow,” he says. “I think it’s realistically somewhere between 3%-5%, the difference between a private, not-on-the-market and a public, on-the-market, because demand is higher once you go public, especially in a tight inventory market.”
Proponents of private listings have argued the opposite. Compass said that according to its data, listings that go through its private listing-focused “3PM” marketing plan sell for 2.9% higher. Both Compass and Zillow are far from objective sources on the subject, but both have defended their research.
Anecdotally, Tanzer points to a townhouse listed at $699,000 last year that sat in Chicago’s private listing network while the sellers prepared the home. A buyer who had seen a comparable property offered full list price sight-unseen. Tanzer presented the offer; the sellers asked what the home might draw publicly.
The listing went live, drew more than 30 showings that weekend and multiple offers, and sold above asking, he says.
The economist’s caveat
Paul Carrillo, a professor of economics at George Washington University who studies urban and real estate economics, says the findings track closely with economic theory.
Housing is a market of differentiated goods and heterogeneous buyer preferences, he says, and platforms like the MLS exist to reduce the friction of matching one to the other. Splitting that market should, in theory, produce worse matches and lower prices.
“The results that they present are not surprising at all,” he says. “They go in line with what economists would predict one should find.”
Where he diverged was on the dollar figures.
“I would be a little careful about extrapolating those numbers and making claims about sellers…losing billions of dollars,” Carrillo says. “Because we need to make very strong assumptions to get to those numbers.”
Another recent independent economic analysis found that despite conventional economic wisdom supporting the idea of broad-based market exposure, data from over 20 years showed off-MLS listings selling for a premium.
That study, by University of Georgia Professor Darren Hayunga, also framed the question as more complicated than simple dollars and cents, positing that the efficiency (and privacy) afforded by a pocket listing creates incentives on both sides of a transaction.
Carrillo offers a very different taking, pushing back on reading the price penalty Zillow identified as a straightforward transfer from sellers to buyers.
“It’s not just that sellers are losing. Buyers are also losing, because they would have been willing to pay more if they would have found the perfect home,” he says. A buyer who saves 1% on a home they didn’t really want is still worse off, he argues, than one who paid more for the right match.
He adds that the percentage should not be dismissed as small: homes are the “largest asset that households invest in, so that’s a large number.”
