A $1.8 billion earthquake just hit the real estate industry

On Tuesday afternoon at a courthouse in Kansas City, Missouri, the collective nightmare of the real-estate industry became reality.

For decades, the basic structure of how real-estate agents get paid when they help someone buy or sell their home has remained roughly the same. But over the past few years, some of the most powerful organizations in the business — the National Association of Realtors and several of the country's largest brokerages — have been fighting two multibillion-dollar class-action lawsuits that argue the system is rigged against regular Americans, forcing...