Four antitrust lawsuits against CoStar Group were consolidated in federal court in Virginia for coordinated pretrial proceedings. CoStar Group, an Arlington County company selling commercial real estate listings and data services, faces claims it monopolized those services. Virginia Business reported the move in its August consolidation coverage.
The cases allege violations of Sections 1 and 2 of the Sherman Act. That federal law bars trade restraints and unlawful monopolization. Consolidation organizes pretrial work and decides nothing about liability.
Table of Contents
- What the Virginia consolidation covers
- What the lawsuits allege
- Can you file for money now?
- What else is moving against CoStar?
What the Virginia consolidation covers
Two of the four cases were filed in Virginia, with one each originally filed in California and Washington, D.C., per court records described by Virginia Business. All four now move together for coordinated pretrial proceedings in Virginia federal court.
Coordination reduces duplication on discovery, schedules, and early motions. It does not combine the cases into one trial or decide the merits. Virginia Business emphasized that the reports describe allegations and venue, not a finding of illegal monopoly.
What the lawsuits allege
The lawsuits accuse CoStar of maintaining monopoly power over commercial real estate online listings and information services, Virginia Business stated in its May report on the lawsuits. That report described an April 79-page complaint by Shapiro Hospitalities in the Eastern District of Virginia focused on commercial real estate data practices. Another plaintiff, Brad Oster of New Orleans, subscribed to CoStar's Premium Listing Plan.
Virginia Business reported that he alleged CoStar's dominance came from means other than better products or competitive pricing. MLex / Law360 Real Estate Authority reported that an Aug. 21, 2026 subscriber class action alleged an exclusionary scheme preserving listing dominance and affecting brokers and listing customers.
Can you file for money now?
There is no court-approved claim form or payout now. CoStar, through its general counsel, said it will vigorously defend the claims, the National Law Journal reported in a National Law Journal account of the defense statement.
The company called the monopolization allegations baseless and predicted it will prevail. For now, commercial brokers and paying subscribers face the same fees and listing terms. Virginia Business reported the practical effect: damages or access changes are possible only if plaintiffs later win or settle.
- Keep CoStar invoices, plan renewals, and listing-fee receipts in one folder.
- Note the account name, property addresses, and months paid.
- Watch for a court-approved class notice, not a marketing email.
- Do not pay a third-party service to file an antitrust claim.
What else is moving against CoStar?
Separately, the U.S. Supreme Court on March 23, 2026 declined without comment to hear CoStar's bid to dismiss rival CREXi's antitrust claims, Reuters reported in a Reuters account of the order. The order left a Ninth Circuit revival of those claims intact.
That rival case is distinct from the four consolidated subscriber and broker cases. The Virginia docket will control pretrial steps for the consolidated group. Save monthly proof of what your office paid and what listing access it received.
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