The Federal Trade Commission’s blockbuster antitrust case against Meta kicks off on Monday in a courtroom in Washington. It’s the culmination of a nearly six-year investigation into whether the social media giant broke competition laws in acquiring Instagram and WhatsApp.

At stake is the future Meta’s $1.4 trillion advertising business and the prospect of having to spin off its hugely popular services into separate companies — a corporate breakup the likes of which has not been seen since AT&T’s telephone monopoly was forced to split apart more than 40 years ago.