Compass Claims Zillow Listings Fetch 1.3% Less, Citing 'Zillow Tax' Amidst Legal Battles

Internal research released by Compass International Holdings on June 10, 2024, posits that homes listed on Zillow, the dominant online real estate portal, ultimately sell for approximately 1.3% less on average compared to comparable properties that are intentionally excluded from the platform. This analysis, a significant undertaking by Compass's chief economist Mike Simonsen and chief data officer Dave Crosby, meticulously examined a dataset comprising 296,966 Compass listings that were active between January 2025 and May 2026. Within this extensive sample, 806 listings were deliberately "banned" from appearing on Zillow. The research revealed a notable disparity in sale outcomes: the median sale-to-list price ratio for these "banned" listings stood at a robust 100%, indicating that these homes sold at their asking price or higher. In stark contrast, listings that were accessible on Zillow achieved a median sale-to-list price ratio of 98.7%. Compass has coined this observed price reduction the "Zillow Tax," arguing that despite Zillow's long-standing emphasis on the benefits of broad online exposure for accelerating sales, the actual financial outcome for sellers is a diminished return. For a hypothetical $1 million home, this 1.3% difference translates to a reduction of roughly $13,000 in seller proceeds.

This study arrives at a critical juncture, as Compass and Zillow are deeply embroiled in a series of escalating legal and competitive conflicts. The friction intensified last June when Zillow implemented its Listing Access Standards policy. In response, Compass initiated an antitrust lawsuit, alleging that Zillow was exploiting its substantial market power to unfairly disadvantage Compass and stifle competition within the broader real estate industry. Although Compass voluntarily dismissed this lawsuit in March 2024, the legal battles were far from over. Zillow subsequently filed its own antitrust lawsuit in May 2024, accusing Compass and Midwest Real Estate Data (MRED), a prominent multiple listing service (MLS) provider, of a coordinated effort to cut off the Chicagoland MLS's data feed to Zillow. Adding another layer to the scrutiny, a House Judiciary subcommittee is currently investigating a nationwide private listing network partnership between MRED and Compass, seeking to understand its implications for market dynamics. Further demonstrating the acrimonious relationship, Compass filed a series of Code of Ethics complaints earlier in June 2024, asserting that Zillow has engaged in widespread false advertising claims across 26 states, 55 MLSs, and 30 Realtor associations. The methodology employed by Compass's economists, utilizing quantile regression, found the 1.3 percentage point difference in sale-to-list ratios between the Zillow-banned and non-banned listings to be statistically significant, lending considerable weight to their "Zillow Tax" hypothesis.