The verdict followed a two-week trial in federal court in Kansas City, where the case had drawn widespread attention for challenging widely used real estate industry practices.

The jury award will be automatically tripled under U.S. antitrust law to more than $5.3 billion, said Michael Ketchmark, the lead lawyer for the plaintiffs. "Today was a day of accountability," Ketchmark said.

The defendants also included Keller Williams and Berkshire Hathaway-owned HomeServices of America and two of its subsidiaries. The class members include sellers of more than 260,000 homes in Missouri and parts of Kansas and Illinois between 2015 and 2012.

HomeServices said it was disappointed by the verdict and planned to appeal.

Keller Williams spokesperson Darryl Frost said the company would consider options for an appeal. "This is not the end," Frost said.

A spokesperson for the National Association of Realtors, Mantill Williams, also said it would appeal and ask the court to reduce the damages amount.

The plaintiffs claimed the association and corporate defendants drove up the commission, upwards of 6%, that home sellers pay to brokers representing buyers.

The home sellers called the compensation rule "a market-shaping and distorting rule that has severe anticompetitive effects."

The realtors association, Keller Williams and HomeServices have denied any wrongdoing.

Two other defendants, Re/Max and Anywhere Real Estate, agreed to settlements without admitting liability before the trial. Anywhere planned to pay $83.5 million, and Re/Max said it would pay $55 million, pending court approvals.

(Reporting by Mike Scarcella in Maryland; Editing by David Bario, Chizu Nomiyama and Jonathan Oatis)

By Mike Scarcella