Federal Court Appoints Plaintiffs’ Leadership in Antitrust MDL Challenging CoStar’s Alleged Monopoly Over Commercial Real Estate Data and Listing Services
RICHMOND, Va. — A federal judge has appointed DiCello Levitt Partner Steven L. Groopman as Interim Co-Lead Counsel in multidistrict antitrust litigation against CoStar Group, Inc. and CoStar Realty Information, Inc.
U.S. District Judge David J. Novak approved the plaintiffs’ leadership structure on August 27, 2026, appointing Groopman alongside Natasha J. Fernández-Silber of Edelson PC and Michael G. Dickler of Sperling Kenny Nachwalter, LLC.
The litigation alleges that CoStar unlawfully monopolized the commercial real estate (CRE) online listing and information services markets, including through its CoStar and LoopNet platforms. DiCello Levitt, Webster Book LLP, and Sperling Kenny Nachwalter filed the first antitrust class action challenging the alleged conduct in April 2026. The complaint alleges violations of Sections 1 and 2 of the Sherman Act and seeks damages and injunctive relief to restore competition.
According to the complaint, CoStar used restrictive customer agreements and other practices to limit brokers’ ability to share their own listings and data with competitors, raise barriers to entry, and charge supracompetitive prices.
The DiCello Levitt team on the matter is led by Steven Groopman and includes Greg Asciolla, Jonathan Crevier, Geralyn Trujillo, Corey Lipton, and Theo Salem-Mackall.
The Court also appointed Deborah A. Elman of Garwin Gerstein & Fisher LLP as Chair of the Plaintiffs’ Steering Committee, with Evelyn Y. Riley of Cuneo Gilbert & LaDuca LLP and Joseph C. Bourne of Lockridge Grindal Nauen PLLP serving as members. Steven T. Webster of Webster Book LLP will serve as local counsel.
The case is In re: CoStar Group, Inc., et al., Antitrust Litigation, MDL No. 3:26-md-03192, in the U.S. District Court for the Eastern District of Virginia.
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DiCello Levitt LLP is one of the leading plaintiffs’ law firms in the United States. Nationally recognized for our work in high-stakes class actions, mass torts, and complex litigation, we have recovered more than $25 billion for clients, including individuals, businesses, and communities. We take on some of the world’s most powerful interests, pursuing justice that reshapes industries and improves lives.
Built for trial, DiCello Levitt is among the few plaintiffs’ firms with a dedicated trial center, where our acclaimed trial lawyers bring both art and science to courtroom preparation and trial strategy. We are frequently appointed to lead major multidistrict litigation (MDLs) and consistently recognized among the nation’s top plaintiffs’ firms by Chambers USA, Benchmark Litigation, and The National Law Journal, which has named DiCello Levitt Plaintiffs’ Firm of the Year and Trial Strategy Innovation Firm of the Year.
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