AI is reinforcing Big Tech's grip on advertising growth

Google, Meta and Amazon already capture 56% of U.S. advertising revenue (excluding political), up from 53% in 2024, and the migration toward AI-automated campaign tools is concentrating an even greater share of future growth, according to Madison & Wall estimates cited by Digiday. Google rose from 28% to 29% share, Meta from 17% to 19%, Amazon from 8% to 9%, while everyone else's combined share fell from 47% to 43%. Madison & Wall puts AI-directed or automated spending at roughly 12% of the U.S. market today, up from 2% in 2023, and projects it to reach 27% by 2030. "We say in the U.S., it's 56% of the total is the big three now. It's going to be a little higher this year. We think it'll be a little higher every year for the next five because they're just going to outperform the average every year," Madison & Wall's Luke Stillman told Digiday. The IAB separately revised its 2026 U.S. ad spend forecast up from 9.5% to 12.3% growth, with CTV up 15.6% and commerce media up 13.6%.

The crux

AI is not a competitive reset that levels the playing field; it is a compounding advantage for the three platforms that already hold the most data, inventory and advertiser relationships, and the market's incremental growth is flowing disproportionately to them.

Sell-side read

Independent publishers are competing for a shrinking slice of a growing pie. The differentiated first-party data and direct audience relationships a publisher owns are the only assets that keep it from being resold inside a platform's automated black box.

Watch

Whether any of Stillman's three escape routes materializes (a consumer behavior shift, a new computing platform, or meaningful regulation), and what the Google antitrust remedy actually does to GAM's grip once implemented.