Over the past few years, antitrust enforcers have zeroed in on some of the biggest names in digital advertising. This report reviews key legal structures in antitrust regulation and explores challenges that have emerged with digitization.

Key Question: What is antitrust law, and who’s in charge of enforcing it?

Key Stat: In 2024, nearly two-thirds of US digital ad dollars will go to Amazon, Apple, Google, Meta, and Microsoft. As they’ve amassed market share, these Big Tech platforms have attracted the attention of antitrust regulators around the world.