CoStar monopoly lawsuits consolidated in Virginia. Four consolidated suits to be heard in Eastern District of Virginia * Four antitrust lawsuits against CoStar consolidated in Virginia federal court * Two suits were filed in Virginia, one each in California, Washington, D.C. * Lawsuits allege CoStar violated Sections 1 and 2 of Sherman Act Four antitrust lawsuits filed against Arlington County-based real estate data and analytics company CoStar Group have been consolidated in federal court in Virginia. Per court records, the U.S. Judicial Panel on Multidistrict Litigation earlier this month combined three similar suits filed earlier this year in Virginia, California and Washington, D.C. A fourth suit filed later by a CoStar customer was added to the consolidated suits, which will be heard by Judge David J. Novak for the U.S. District Court for the Eastern District of Virginia. The suits all allege CoStar participated in monopolistic practices. The initial Virginia case, Shapiro Hospitalities dba Grand & Co. v. CoStar Group, et al., was filed in the Eastern District in April. The complaint, brought forth by Shapiro Hospitalities, claims CoStar violated federal antitrust law by maintaining monopoly power as the dominant provider of commercial real estate, or CRE, online listings and information. The complaint in Shapiro alleged CoStar coerced the three largest CRE brokerages into noncompete agreements, limiting the information that could be shared with CoStar competitors and excluding any rival platform from competing without access to the information. "This is a rare case about a company that has perpetrated an anticompetitive scheme so pernicious that its own customers openly lament how it has destroyed competition, leaving them no choice but to pay its supracompetitive prices," the complaint states. The filing specifically alleges violations of Sections 1 and 2 of the Sherman Act. "By restraining customers' ability to share their own CRE information with CoStar competitors, CoStar has created and maintained a dangerous probability that its attempt to monopolize will succeed," the complaint states. In the Aug. 14 decision by the U.S. Judicial Panel on Multidistrict Litigation, the panel wrote that CoStar opposed consolidation but asked that the actions be transferred to Virginia should consolidation occur. "We find that the Eastern District of Virginia is the most appropriate transferee district for this litigation," U.S. Judicial Panel on Multidistrict Litigation Acting Chair Matthew F. Kennelly wrote. "CoStar is headquartered in this district, and most parties support centralization there, in the first instance or in the alternative." Kennelly selected Novak to preside over the consolidated action, writing that he "is familiar with the contours of multidistrict and complex litigation, and we are confident he will steer this matter on an efficient and prudent course." The cases transferred to Virginia include Malm Inc. v. CoStar Group from the Central District of California and One Real Estate, dba The One Street Co. v. CoStar Group from the District of District of Columbia. The fourth case, Oster v. CoStar Group, was filed in the Eastern District of Virginia after consolidation proceedings began. In the new filing, plaintiff Brad Oster, a New Orleans resident who has paid for a "Premium Listing Plan" and CRE listing services from CoStar, alleged similar violations of the Sherman Act. "CoStar did not achieve this dominance through superior products or competitive pricing," the complaint states. "It achieved dominance by eliminating competitors through acquisition and litigation, and then by deploying a self-reinforcing anticompetitive scheme designed to prevent any new competitor from challenging its position." CoStar has 8,400 employees and 86 offices in 15 countries. In 2025, the company reported $3.2 billion in revenue, up 19% over 2024's $2.7 billion. Its websites attracted an average of 118 million unique monthly visitors during the second quarter of this year.

CoStar hit with consolidated antitrust challenge over property data. By CPI | August 25, 2026 CoStar Group is confronting a widening antitrust battle, with several lawsuits accusing the commercial real estate data provider of using its market position to suppress competition even as the company seeks to dismiss a separate case alleging it helped facilitate rent price-fixing. Four antitrust cases have been consolidated in federal court in Virginia, according to an Aug. 25 report by the Washington Business Journal. The lawsuits accuse Arlington, Virginia-based CoStar of monopolistic practices involving commercial real estate data and information services. The litigation puts fresh scrutiny on a business model built around collecting, organizing and selling property and transaction information relied upon by brokers, landlords, investors and other commercial real estate professionals. One of the cases was initially filed in April by Shapiro Hospitalities LLC, doing business as Grand & Co., in the U.S. District Court for the Eastern District of Virginia. The complaint alleges CoStar controls roughly 80% of national markets for internet-based commercial real estate listing and information services, according to the plaintiffs' law firm, DiCello Levitt. That figure is an allegation and hasn't been established by a court. The plaintiffs contend that CoStar reinforced its position through contractual restrictions and other measures that limited customers' ability to provide their own listings and data to competing platforms. They are seeking damages as well as court-ordered changes intended to increase competition, according to DiCello Levitt. The consolidated monopoly litigation comes as CoStar also battles a different proposed class action focused on the exchange of commercial leasing information. FitFactariDC LLC, a commercial tenant, sued CoStar and five major real estate brokerages - CBRE Group Inc., Colliers International Group Inc., Cushman & Wakefield Plc, Jones Lang LaSalle Inc. and Newmark Group Inc. - in Illinois federal court in June. The plaintiff alleges the companies participated in a so-called hub-and-spoke conspiracy that allowed sensitive leasing information to move among competitors and contributed to higher rents. According to the Washington Business Journal's Aug. 25 report, CoStar has moved to dismiss that price-fixing case. The company's effort to knock out the lawsuit underscores the distinct legal fronts it now faces: allegations that it monopolized commercial real estate information markets and claims that its data platform facilitated anticompetitive coordination among brokerage firms. Please add Competition Policy International to your preferred sources list so its news, data and interviews show up in your feed. Thanks! CoStar has rejected the price-fixing allegations. General Counsel Gene Boxer previously described the complaint as poorly conceived and said the company expected to prevail, according to Bisnow. The disputes arrive as courts increasingly wrestle with how traditional antitrust law applies to data-sharing platforms and information services. Plaintiffs in such cases have sought to show that exchanging competitively sensitive information through third-party systems can reduce independent decision-making even without an old-fashioned agreement among rivals. CoStar has already prevailed at an early stage in another data-sharing antitrust dispute. In August 2025, U.S. District Judge Robert Lasnik in Seattle dismissed a proposed class action accusing CoStar's Smith Travel Research unit and luxury hotel operators of fixing hotel-room prices through an industry benchmarking program. Lasnik concluded that the plaintiffs hadn't sufficiently alleged an agreement violating Section 1 of the Sherman Act, though he allowed them an opportunity to amend their complaint. That ruling doesn't determine the outcome of the newer commercial real estate cases, which involve different plaintiffs, markets and allegations. But the cases collectively raise a question increasingly important to industries built around proprietary databases: when does the aggregation and distribution of market information cross the line from providing useful intelligence to restraining competition? For CoStar, the answer could carry consequences beyond damages in any individual lawsuit. The company's commercial real estate databases sit at the center of an information network used across the industry, making challenges to the way that data is collected, protected and distributed potentially significant for both CoStar and its customers. The allegations in the pending cases remain unproven, and CoStar is contesting the claims.