OneKey MLS has joined California Regional Multiple Listing Service (CRMLS) in its federal lawsuit against Compass, adding another major player to a growing legal battle over private listings, seller choice and the rules governing how homes are marketed.
The New York-based MLS, which serves more than 40,000 real estate professionals across Long Island, the Hudson Valley and New York City, was added as a plaintiff in an amended complaint filed Tuesday in the U.S. District Court for the Southern District of New York.
The move comes just a week after OneKey publicly rejected Compass’s demands to loosen its listing rules. Opposition to the brokerage’s private-listing strategy has become more organized, more confrontational and increasingly focused on defending the cooperative MLS system in court.
“This case raises questions that extend far beyond any one company or marketplace,” OneKey CEO Richard Haggerty said in a press release published Tuesday. “They go to the core of how publicly marketed listing information is shared, how consumers access that information, and what participants should reasonably expect from a marketplace they collectively support.”
OneKey pushes back harder against Compass demands
Richard Haggerty | OneKey MLS
OneKey’s decision to join CRMLS brings together two of the nation’s largest MLSs that received nearly identical legal threats from Compass in September and subsequently refused to change their rules.
Both organizations are now asking a federal judge to declare their cooperation policies lawful under federal and applicable state antitrust laws and block Compass from pursuing its threatened claims.
CRMLS CEO Art Carter, whose organization became the first MLS to file a preemptive lawsuit against Compass earlier this month, welcomed OneKey’s addition to the case.
“I’m looking forward to working alongside OneKey MLS in the fight to protect the open marketplace and keep real estate fair and transparent for brokers, agents and consumers alike,” Carter said in OneKey’s Tuesday announcement.
At the center of the dispute is Compass’s demand that MLSs stop fining agents for publicly marketing office-exclusive listings without submitting those properties to the MLS.
In its Sept. 8 demand letter, Compass gave OneKey until Oct. 6 to agree or face a federal antitrust lawsuit. OneKey received an extension and formally rejected the demands Oct. 20. Under OneKey’s rules, sellers can keep properties private through office-exclusive arrangements, but publicly marketing a property triggers a requirement that it be submitted to the MLS within one business day.
Compass argues that the rules unlawfully restrict seller choice and agents’ ability to carry out their clients’ marketing instructions.
“It’s almost as if CRMLS and OneKey MLS are asking people to ignore the evidence that proves their claims aren’t true,” a Compass International Holdings spokesperson wrote in a statement shared with Inman. “For years, seven of the top 25 MLSs, covering 340,000 agents across 12 states, have allowed agents to publicly market ‘office exclusives’ without fines, and none of the problems they warn about have happened. If what we are asking for is so bad, why has it worked for years in nearly 30 percent of the country?”
OneKey has also launched a new landing page outlining its position in the dispute and making key documents publicly available, including Compass’s September demand letter, OneKey’s formal responses and the amended complaint filed Tuesday.
“There is a fundamental difference between a seller choosing to limit exposure and a brokerage publicly marketing a property while withholding it from the shared marketplace,” the organization states on its website.
A dispute that has been months in the making
The amended complaint reveals that tensions between OneKey and Compass began months before September’s demand letter.
The filing shows that on March 21, following a notice from OneKey explaining its listing options, Compass CEO Robert Reffkin emailed Haggerty directly, calling the MLS’s rules “an illegal restraint of trade.”
Reffkin warned that Compass was “on a clear path to pursue antitrust claims with three times damages” unless MLSs changed their policies and urged OneKey to “just stop fining agents for publicly marketing off-MLS.”
“Litigation is likely to start next month,” Reffkin wrote, according to correspondence included in the filing.
The complaint also provides details about OneKey’s enforcement actions. Since January 2025, OneKey says it has issued 156 fines totaling approximately $407,800 for violations of its cooperation rule across 90 brokerage offices. Only five fines were issued to Compass, totaling $13,800. Of that amount, $9,300 was waived, one fine was reduced to $1,500 and paid, and one issued in September remains unpaid.
The filing also alleges that Compass sought to stop OneKey from sharing certain data about its listings and agents with third-party tech companies that help competing brokerages identify and recruit agents.
The MLSs also reiterated an argument that has become central to their fight against Compass, accusing the brokerage of attempting to “free-ride on the listing contributions of every other participating brokerage while hoarding its own inventory.”
MLS opposition is gaining more momentum
OneKey’s addition brings the number of MLSs engaged in litigation against Compass to eight, with nine organizations publicly pushing back against the brokerage’s demands.
Last week, six MLSs — Arizona Regional MLS, Bridge MLS, Canopy MLS, REcolorado, Hive MLS and Doorify MLS — filed a separate federal lawsuit challenging Compass’s threatened antitrust claims.
The legal pushback follows Reffkin’s contentious appearance at the Council of Multiple Listing Services conference in late September, where he warned MLS leaders about impending lawsuits if they continued penalizing agents for publicly marketing listings outside the MLS.
CMLS has also outlined plans for a legal action fund to support MLSs defending their rules, while CRMLS has launched a separate legal defense effort.
In just the past several weeks, the conflict has grown to involve at least nine MLS organizations representing approximately 272,000 subscribers, members and other professional users across major real estate markets. With eight of those MLSs now engaged in litigation against Compass, the fight has increasingly become about more than private listings, raising questions about the future of the cooperative MLS system and the role it plays in residential real estate.
