Ten days remain before Google finishes silently converting a large slice of the world’s Search advertising to A.I. Max, the automated system that decides which queries trigger an ad, rewrites the headline copy, and can substitute a landing page the advertiser never selected. The automatic upgrade began September 1 and concludes September 30. There’s no opt-out.

The scope is defined by two legacy settings. Campaigns previously using Automatically Created Assets are migrated with search term matching and text customization enabled by default. Campaigns using campaign-level broad match are upgraded with search term matching turned on. Google says brand inclusions and exclusions carry over. Dynamic Search Ads, originally part of this sweep, were granted a reprieve in June after advertiser feedback and rescheduled to February 2027. Everyone else is on the current clock.

Google disclosed the rollout on its Ads and Commerce blog in April and reaffirmed it in June. Since August 3, the company has blocked the creation of new legacy campaign structures across its interface, Google Ads Editor, and the Google Ads API, closing the escape hatch before the migration itself began.

The performance evidence is unusually contested for a Google product launch. Google claims the full A.I. Max feature suite delivers, on average, 7% more conversions or conversion value at similar cost. Independent testing points the other way. A Smarter Ecommerce study across 600 accounts, reported by Search Engine Land, found A.I. Max delivering a 35% lower return on ad spend than traditional match types. In a four-month test, Xavier Mantica measured cost per conversion at $100.37 under A.I. Max, against $43.97 for phrase match and $52.69 for exact match. Ezra Sackett tested 30,000 search terms and reported that 99% of A.I. Max impressions produced zero conversions.

That gap between vendor number and third-party number is the actual story. It’s the pattern that defined the shift to Performance Max in 2021: an opaque system, a modest headline lift, and a long tail of small advertisers discovering months later that their budgets funded queries they’d never approved.

Small budgets fare worst here because they give the model the least data to learn from. Before September 30, the defensive work is narrow and known: pull the search-terms report, harden negative keywords, confirm brand exclusions carried over, and check whether text customization and final URL expansion are on. It’s the same audit Google’s decision to let keyword campaigns reach A.I. Mode placements already forced, and the same audit implied by the new site-level scorecard for A.I. Search visibility without clicks.

The Search surface is being rewritten from three directions at once. The advertisers who notice first will be the ones who read their October reports carefully.

Sources