Here’s how we can break up Big Tech

By Elizabeth Warren — Twenty-five years ago, Facebook, Google, and Amazon didn’t exist. Now they are among the most valuable and well-known companies in the world. It’s a great story — but also one that highlights why the government must break up monopolies and promote competitive markets.

In the 1990s, Microsoft — the tech giant of its time — was trying to parlay its dominance in computer operating systems into dominance in the new area of web browsing. The federal government sued Microsoft for violating anti-monopoly laws and eventually reached a settlement. The government’s antitrust case...