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.

By Jody Godoy WASHINGTON (Reuters) -Facebook parent Meta Platforms bought up nascent rivals Instagram and WhatsApp after its attempts to compete had failed, an attorney for the U.S. Federal Trade Commission said at the beginning of a high-stakes trial in Washington on Monday,