The long-awaited antitrust trial between Meta and the Federal Trade Commission kicked off on April 14th. Over about two months, DC District Court Chief Judge James Boasberg is hearing arguments about whether then-Facebook illegally monopolized the market for “personal social networking services” through its acquisitions of Instagram and WhatsApp.

WASHINGTON—Facebook parent Meta Platforms faces a high-stakes trial in Washington starting on Monday on claims it built an illegal social media monopoly by spending billions of dollars to acquire Instagram and WhatsApp, in a case where U.S. antitrust enforcers seek to unwind the deals.

Meta Platforms Inc. faces a historic antitrust trial Monday that could force the tech giant to break off Instagram and WhatsApp, startups it bought more than a decade ago that have since grown into so