AI Max by Default: The Verified Dossier on Google's September Auto-Upgrade

Research cutoff: August 25, 2026
Migration window examined: September 1 through September 30, 2026

Evidence legend

Every claim below carries one of five marks. Hover any mark for its label.

• ● Verified fact. A directly documented product mechanic, dated event, filing figure, or other checkable fact.
• ■ Company claim. A performance or benefit statement from Google, Microsoft, or a named advertiser case study distributed by the platform.
• ◆ Independent measurement. A third party's analysis of observed data. Independence does not mean randomized or bias-free.
• ○ Anecdote. A practitioner report without enough disclosed data to evaluate causally.
• △ Inference. An interpretation that follows from cited facts but is not itself stated by the source.

Research and access note

● Mechanics were checked against current Google product, developer, API, and Editor documentation. Commercial and practitioner sources were searched and extracted with the Choice OMG proxied Firecrawl service, then important pages were checked with a second web renderer where possible. Firecrawl exposed search, scrape, map, and crawl operations, but no location selector or geographic response metadata. Therefore, this dossier does not claim that any page was verified from multiple countries. LinkedIn blocked automated retrieval, so the Microsoft global-rollout item relies on accessible reporting that reproduces the announcement. Google help pages generally have no publication date; those are identified as undated and carry the August 25, 2026 access date.

● After drafting, every load-bearing claim was re-verified against its cited source: 56 claims were checked and six citation-level corrections were applied before publication, all of them in Google primary-source attribution rather than in the data. SEC filings, DOJ documents, and earnings-call transcripts were read from primary documents. Two Google developer-blog pages that block automated retrieval were verified from Wayback Machine captures of the same pages, and the dead 2014 close-variants announcement was verified from DOJ trial exhibit UPX8049.

1. Executive summary

1. ● The September event is a progressive in-place conversion of eligible Search campaigns, not a new campaign type and not a same-day global flip. From September 1 through September 30, 2026, Google will convert campaigns using the campaign-level broad match setting or standalone automatically created assets, now called text customization, into AI Max. Google exposed per-campaign migration timestamps in the Ads API. Creation of new legacy configurations was blocked on August 3 across the web UI, Editor, and all API versions. (Google Ads Developer Blog, published August 12, 2026)

2. ● The cohort defaults are asymmetric. A broad-match-setting campaign receives search term matching on, text customization off, and final URL expansion off. An ACA campaign receives search term matching on, text customization on, and final URL expansion off. In both cases, the AI Max umbrella is enabled at campaign level, while search term matching can be controlled at ad-group level. (Google Ads Developer Blog, published August 12, 2026)

3. ● Dynamic Search Ads are not part of the September 2026 conversion. Google originally announced a September 2026 DSA migration on April 15, then changed it on June 11. The current schedule is in-account pre-migration banners starting September 2026, an official reminder notification on January 15, 2027, and automatic migration from February 1 through February 28, 2027. Google's update says, “we are extending the timeline for Dynamic Search Ads sunset and auto-upgrade, which will begin in February 2027.” (Google product blog, published April 15, 2026, updated June 11, 2026; Google Ads Developer Blog, published August 12, 2026)

4. ● September 1 is not the last chance to disable AI Max. Before migration, owners can prevent this specific automatic conversion by turning off the legacy feature. After conversion, the current UI permits the AI Max umbrella and each applicable sub-setting to be changed. Google does not promise that this opt-out will remain available forever, so “permanent” is not supported by public documentation. (Google text-customization instructions, undated, accessed August 25, 2026; Google AI Max setup instructions, undated, accessed August 25, 2026)

5. ● Advertisers keep substantial controls, but the control model changes. AI Max adds campaign and ad-group brand inclusions, campaign brand exclusions, campaign URL exclusions, ad-group URL inclusions, ad-group locations of interest, negative keywords, and source-level reporting. The search terms report labels expanded traffic as match type “AI Max” and adds a Source column; the cited reporting page instructs adding the column but does not document its values, so the broad-versus-keywordless distinction should be confirmed in the live report. Low-volume queries remain hidden under Google's general search-terms privacy threshold. (Google AI Max workings, undated, accessed August 25, 2026; Google AI Max reporting, undated, accessed August 25, 2026; Google search terms report, undated, accessed August 25, 2026)

6. ■ Google's current top-line claim is that the full AI Max suite produces 7% more conversions or conversion value at a similar CPA or ROAS than search term matching alone. Earlier launch material claimed 14% versus non-AI-Max campaigns and 27% for campaigns that had obtained more than 70% of conversions from exact and phrase match. Google identifies these as internal non-Retail data, but discloses no account count, randomization method, test duration, dispersion, or significance test. (Google product blog, published April 15, 2026, updated June 11, 2026; Google launch post, published May 6, 2025)

7. ◆ Third-party evidence is mixed and mostly observational. Smarter Ecommerce reported a median 13% increase in conversion value, a median 16% higher CPA, and a median ROAS difference of 0% across more than 250 retail Search campaigns. Location3 reported conversion gains in five franchise experiments. Lunio found AI Max invalid-traffic rates rising from 2.46% in Q4 2025 to 5.28% in Q2 2026 across about 49.5 million AI Max clicks, while standard Search ended at 3.07%. Each dataset has material limitations described below. (Smarter Ecommerce, published March 23, 2026; Location3, published March 18, 2026; Lunio, updated August 14, 2026)

8. △ Google's strongest evidence-backed rationale is adaptation to conversational, multimodal, and less keyword-shaped search. Google says people now provide more context and calls AI Max a way for advertisers to adapt. The strategic case is strong because AI Max maps a landing page, creative, intent, and controls to queries that may never resemble a purchased keyword. (Alphabet Q1 2026 earnings call, published April 29, 2026; Google launch post, published May 6, 2025)

9. △ Revenue is a plausible secondary motive, but the specific premise that paid-click growth is slowing is contradicted by the latest filings. Paid clicks grew 6% in 2025, then 13% in both Q1 and Q2 2026. CPC growth slowed from 7% in 2025 to 5% in Q1 and 3% in Q2. Management nevertheless said new systems let Google serve ads on longer searches that were previously difficult to monetize. Rating: moderate, not strong. (Alphabet 2025 Form 10-K, filed February 5, 2026; Alphabet Q1 2026 Form 10-Q, filed April 30, 2026; Alphabet Q2 2026 Form 10-Q, filed July 23, 2026; Alphabet Q1 2026 earnings call, published April 29, 2026)

10. ● No credible public source located for this dossier gives the share of all Search campaigns or accounts that use standalone ACA or campaign-level broad match, so the September exposure cannot be quantified responsibly. Google said half a million advertisers were using AI Max by July 2026, but that is an adoption count, not the eligible migration population. (Alphabet Q2 2026 earnings call, published July 22, 2026)

2. Track A: definitive mechanics

2.1 Per-cohort conversion table

● If a campaign belongs to both September cohorts, Google's public migration table does not specify which text-customization default wins. That overlap rule is an open question, not a safe assumption. (Google Ads Developer Blog, published August 12, 2026)

2.2 The opt-out, exactly

Before the September migration

After conversion

● The current Google support language is:

“To disable AI Max, toggle to opt out of all AI Max settings.”

“Note that re-enabling AI Max will enable the same features as they were previously set”

“When you disable Text customization, assets will be reported as ‘Removed’ and no longer serve.”

(Google AI Max setup, undated, accessed August 25, 2026)

△ “Permanent opt-out” is too strong. The controls survive the September conversion under today's documentation, and no automatic reactivation is announced. Google has not contracted to preserve those controls indefinitely. The defensible practitioner wording is: owners can disable the bundle or individual features after migration and leave them off under the current product, but future product retirement is uncommitted.

2.3 Reporting and control surface

2.4 Google Ads API and legacy-field deprecation

● The current API exposes the campaign umbrella as Campaign.ai_max_setting.enable_ai_max, text and final-URL automation through Campaign.asset_automation_settings, ad-group search-term control through AdGroup.ai_max_ad_group_setting.disable_search_term_matching, and combined query, ad, and URL reporting through ai_max_search_term_ad_combination_view. Campaign.AiMaxSetting.bundling_required indicates whether the account must enable the suite as a bundle. Messaging restrictions allow up to 40 entries and term exclusions up to 25, with limits documented in the API guide. (Google AI Max API guide, updated August 19, 2026)

● Migrated campaigns can be identified programmatically by selecting campaign.aca_migration_date_time and campaign.broad_match_migration_date_time; the developer post presents the fields as a way to find campaigns already migrated during the month, not as a scheduling control. The post names no API version for the fields; the v25.1 attribution rests on the release notes. (Google Ads API release notes, updated August 19, 2026; Google Ads Developer Blog, published August 12, 2026)

● New API versions released after September 1, 2026 will omit the legacy ACA and campaign-level broad-match entities. Existing versions retain the fields until their standard sunset, which Google described as approximately September 2027. Mutating Campaign.keyword_match_type for an AI Max campaign is deprecated and inapplicable. (Google Ads Developer Blog, published August 12, 2026; Google AI Max API guide, updated August 19, 2026)

● A Google FAQ that still says API and Editor support were expected later in 2025 is stale. API v21 added AI Max fields in August 2025 and Editor 2.10 added AI Max controls in July 2025. Current API documentation overrides that old FAQ sentence. (Google AI Max FAQ, undated, accessed August 25, 2026; Google Ads API v21 announcement, published August 6, 2025; Google Ads Editor 2.10 help, undated, accessed August 25, 2026)

3. Timeline of record

4. Track B: performance evidence, sorted by independence

4.1 Google's claims

4.2 Independent measurements

Lunio: invalid traffic

◆ Lunio compared about 114.5 million Google Search clicks over nine months, from Q4 2025 through Q2 2026: approximately 49.5 million AI Max clicks and 65.0 million standard Search clicks. It says campaigns were compared within the same customers, period, campaign type, sector, and season. AI Max's invalid-traffic rate moved from 2.46% in Q4 to 4.01% in Q1 and 5.28% in Q2. Standard Search moved from 3.72% to 2.98% to 3.07%. Lunio characterizes the ending gap as 72% higher invalid traffic for AI Max and the nine-month movement as a 114% rise for AI Max versus a 17% decline for standard Search. (Lunio, updated August 14, 2026)

◆ In Lunio's retail subset, AI Max's share of Search clicks rose from about 33% to 55%, and it accounted for 68% of invalid Search clicks in Q2. The broader retail report analyzed 414 million ad clicks across 88 retail accounts and multiple platforms. The AI Max comparison is the nested Search cohort, not 414 million AI Max clicks. (Lunio AI Max analysis, updated August 14, 2026; Lunio retail report, updated August 14, 2026)

◆ Limits: the design is observational; participating customers self-selected into AI Max; account count for the Search comparison is not stated; conversion quality is not measured; Lunio sells invalid-traffic software; and its classifier is not independently audited in the article. Like-for-like matching reduces, but cannot eliminate, selection and mix differences. A separate 2025 Lunio single-client exercise compared 404 AI campaigns with 491 controls and reported a difference-in-differences increase from a 3.7% baseline to 5%, but one client is not a market estimate. (Lunio, updated August 14, 2026)

Smarter Ecommerce, Mike Ryan

◆ Smarter Ecommerce examined more than 250 retail Search campaigns using AI Max within a base of 600 active ecommerce accounts. About 16% of those accounts were testing AI Max. The March 2026 analysis reported a median 13% increase in conversion value, a median 16% increase in CPA, and a median ROAS difference of 0%, with a reported ROAS distribution from +42% to -35%. (Smarter Ecommerce, published March 23, 2026)

◆ Its query analysis included one million AI Max impressions and found an 80/20 concentration pattern. One account showed AI Max matches that were 49% and 63% broad; another competitor-expansion example reached effectively 100% of a comparison and 69% of total Search impressions. One Search Partners Network example contributed half of a campaign's 500,000 monthly impressions and converted at 0.07%, versus 3.04% for Google Search. (Smarter Ecommerce, published March 23, 2026)

◆ Limits: this is campaign-versus-remaining-revenue analysis, not randomized treatment assignment; spend levels and account counts vary by section; cannibalization across campaigns is not controlled; medians hide tail outcomes; and the publisher sells Google Ads management software. A March podcast describes “conversions” where the written article specifies “conversion value,” so this dossier uses the written metric. (Smarter Ecommerce article, published March 23, 2026; Smarter Ecommerce podcast, published March 10, 2026)

Location3 franchise experiments

◆ Location3 reports Google Ads Experiments run from December 1, 2025 through January 31, 2026 across five home-services franchise locations. It says every location increased conversions. Reported conversion lifts were 97%, 720%, 318%, 410%, and 350%. CPA was slightly higher at the first location, improved 63% at the second, was approximately flat at the third, and improved 30% and 50% at the fourth and fifth. (Location3, published March 18, 2026)

◆ Limits: the clients are unnamed; absolute conversions, spend, randomization, confidence intervals, and spillover controls are not reported; the sample is five locations in one vertical over two months; and the agency recommends keeping final URL expansion off for tightly local campaigns. These are favorable experiments with limited external validity. (Location3, published March 18, 2026)

Adalysis-guided creative tests reported by Brad Geddes

◆ Three companies, ecommerce, B2B lead generation, and B2C lead generation, tested text customization. Each selected four non-brand campaigns, two closely optimized and two more neglected, with at least $20,000 monthly spend and at least 100 ad groups. Final URL expansion was off. Excluding the B2B case, about 19% of generated assets were removed before receiving many impressions. (Search Engine Land, published July 28, 2026)

◆ Results ran in both directions. Ecommerce initially looked successful, but account revenue fell after traffic was cannibalized from other campaigns; the rerun used added keywords, negatives, and audiences. In B2B, CTR rose while conversion rate fell as ads attracted B2C users; the company stopped after three weeks, restored pins and removed generated assets, and returned to pretest performance within a week. In B2C and ecommerce, human-managed assets remained stronger in mature campaigns while automated assets helped neglected long-tail campaigns. (Search Engine Land, published July 28, 2026)

◆ Limits: only three accounts, each contributing four campaigns, are described; results are mainly directional rather than numeric; the companies are unnamed; treatment assignment and confidence intervals are absent; account-level cannibalization complicated the first result; and the author co-founded a PPC software vendor. The design is still valuable because it isolates text customization by keeping final URL expansion off. (Search Engine Land, published July 28, 2026)

Optmyzr and older broad-match context

● No qualifying Optmyzr AI Max before-and-after or controlled study was located through August 25, 2026. Optmyzr has published practitioner commentary and webinars, but not a disclosed AI Max sample comparable to the studies above. Its older match-type benchmark covered 4,000 accounts meeting tenure, spend, and non-brand criteria and found exact match ahead of broad match on ROAS, CPA, CTR, and conversion rate, with near-even CPC results. That 2024 study is component context, not evidence about AI Max. (Optmyzr State of PPC study, published March 13, 2024; Optmyzr 2026 webinar takeaways, published April 20, 2026)

4.3 Practitioner and press reports

4.4 What the performance evidence supports

△ Evidence in favor is strongest where automation fills genuine coverage gaps: neglected long-tail campaigns, new query forms, and small local tests with disciplined URL and negative controls. The evidence against is strongest where existing campaigns already have refined creative and query governance, where B2B prequalification depends on careful wording, where competitor or partner-network traffic can expand quickly, and where account-level cannibalization makes campaign metrics look better while total revenue worsens. This synthesis follows the independent measurements above; no cited study establishes a universal average causal effect.

● Brand-safety and offer-misrepresentation risk is not only anecdotal. Google's own help warns owners to keep website content accurate and monitor generated content, while the three-account creative test removed about 19% of generated assets outside the B2B case and observed B2B audience misqualification despite messaging restrictions. Google's contrary claim is that its quality models ground assets in the advertiser's pages and offerings. (Google text-customization help, undated, accessed August 25, 2026; Search Engine Land, published July 28, 2026)

5. Track C: motivations, argued from evidence

5.1 Revenue mechanics

Rating: moderate

Supporting evidence

• ● Alphabet reported Google Search and other revenue of $198.084 billion in 2024 and $224.532 billion in 2025. It reported paid clicks up 6% and cost per click up 7% in 2025. The filing lists advertiser competition for keywords among the factors that affect CPC. (Alphabet 2025 Form 10-K, filed February 5, 2026)
• ● For Q1, Search and other revenue was $50.702 billion in 2025 and $60.399 billion in 2026. Paid clicks increased 13% and CPC increased 5%. (Alphabet Q1 2026 Form 10-Q, filed April 30, 2026)
• ● For Q2, Search and other revenue was $54.190 billion in 2025 and $63.271 billion in 2026. Paid clicks increased 13% and CPC increased 3% for the quarter; for the first six months, the figures were 13% and 4%. (Alphabet Q2 2026 Form 10-Q, filed July 23, 2026)
• ■ Management said Google had expanded its ability to deliver ads on “longer, more complex searches” that had previously been difficult to monetize. Google also said AI Max had reached billions of net-new queries. (Alphabet Q1 2026 earnings call, published April 29, 2026; Alphabet Q4 2025 earnings call, published February 4, 2026)
• △ Broader and keywordless eligibility can place more advertisers into consideration for a query. More eligible bids can increase auction density, which can support price realization or monetize previously unserved inventory. The filings establish that auction competition affects CPC, but they do not isolate AI Max as the cause.

Contradicting evidence and strongest counter-argument

• ● The asserted premise that click-volume growth is slowing does not fit the latest period: paid-click growth rose from 6% for 2025 to 13% in each of Q1 and Q2 2026, while CPC growth slowed from 7% to 5% and then 3%. (Alphabet 2025 Form 10-K, filed February 5, 2026; Alphabet Q1 2026 Form 10-Q, filed April 30, 2026; Alphabet Q2 2026 Form 10-Q, filed July 23, 2026)
• ● Alphabet attributes Search growth to more queries, advertiser spend, and ad formats and delivery. It does not disclose an AI Max contribution to CPC or Search revenue. (Alphabet Q1 2026 Form 10-Q, filed April 30, 2026; Alphabet Q2 2026 Form 10-Q, filed July 23, 2026)

Best steelman of Google's official rationale

△ AI Max can create incremental advertiser value and Google revenue at the same time. If conversational searches were previously hard to match or monetize, a system using intent, pages, creative, and Smart Bidding may show a relevant ad where a literal-keyword system showed none. Revenue growth would then be a consequence of product coverage rather than proof that Google designed the migration mainly to inflate CPC.

5.2 The AI search transition

Rating: strong

Supporting evidence

• ■ Google said, “People no longer search in fragments; they search conversationally and share more context.” The same earnings call said AI Max helps advertisers adapt to that behavior. (Alphabet Q1 2026 earnings call, published April 29, 2026)
• ● Google's launch connected AI Max to AI Overviews, Lens, exploratory searches, multimodal searches, and complex queries. AI Max uses keywordless technology plus broad match, creative generation, page selection, and controls rather than relying only on a literal keyword list. (Google launch post, published May 6, 2025; Google AI Max workings, undated, accessed August 25, 2026)
• ◆ Seer analyzed 5.47 million queries, 2.43 billion organic impressions, and 296.9 million paid impressions across 53 brands from January 2025 through February 2026. Organic CTR on AI-Overview queries was 2.4% in February 2026 versus 3.2% in January 2025. Paid CTR was 16.2% for AI-Overview queries versus 21.8% for non-AI-Overview queries in February 2026. (Seer Interactive, published April 24, 2026)
• ◆ Ahrefs compared 150,000 informational keywords with AI Overviews against 150,000 without them and reported that position-one organic results were associated with a 58% lower average CTR when an AI Overview was present. (Ahrefs, published February 4, 2026)
• ◆ SE Ranking inspected 50,032 commercial keywords in 20 niches and found text ads on 14,733, or 29.45%, of AI Mode result pages. Ad presence rose across the source's CPC bands, from 24.33% below $2 to 53.56% above $10. (SE Ranking, published July 14, 2026)

Limits and strongest counter-argument

• ◆ Seer's current AI-Overview label is applied retrospectively, its model does not control seasonality, and the data are observational. Ahrefs uses desktop Search Console data and different keyword cohorts. SE Ranking is a result-page snapshot, not a click or conversion study. (Seer Interactive, published April 24, 2026; Ahrefs, published February 4, 2026; SE Ranking, published July 14, 2026)
• △ Conversational query growth explains why Google wants a richer matching system, but it does not by itself justify forcing campaigns that already use ACA or campaign broad match into the AI Max umbrella. Google could have preserved the legacy switches or required explicit consent.

Best steelman of Google's official rationale

△ Keyword lists were designed for short, enumerable expressions of demand. AI-era search can combine constraints, context, images, follow-up turns, and product discovery. An intent and content model is structurally better suited to map those queries to ads, provided that reporting, negative controls, page controls, and creative guardrails remain usable.

5.3 Information asymmetry and lock-in

Rating: moderate

Supporting evidence

• ● Google's search terms report omits queries with insufficient activity under its privacy standards. Search-term insights can group queries without revealing every underlying term. AI Max also allows keywordless eligibility, so the platform's model, not an advertiser-authored positive keyword, determines part of the match set. (Google search terms report, undated, accessed August 25, 2026; Google AI Max workings, undated, accessed August 25, 2026)
• ◆ After Google's September 2020 reporting threshold change, Seer found cost visibility fell overnight from 98.7% to 71.0% and click visibility from 98.3% to 77.9%, with both holding at that level through the first seven days. The source did not disclose the client count for that comparison. (Seer Interactive, published September 2, 2020)
• ◆ A one-campaign 2025 audit reported 269 clicks, of which 131 were attached to visible search terms and 138 were not, leaving 51% of clicks and 54% of impressions hidden. (Marlin SEM, published July 9, 2025)
• △ A campaign defined by Google's private matching, creative, and page-selection models is harder to reproduce on another network than a campaign defined by a portable list of keywords, ads, bids, and URLs. Reports expose outcomes and sources, but not the model's complete decision rule or learned state.

Contradicting evidence and strongest counter-argument

• ● AI Max adds, rather than removes, several controls and reports: brand inclusions and exclusions, locations of interest, URL inclusions and exclusions, source labels, and the query-ad-URL view. Negative keywords still apply. There is no sourced evidence that enabling AI Max lowers the general search-term visibility threshold relative to an otherwise identical Search campaign. (Google AI Max reporting, undated, accessed August 25, 2026; Google AI Max workings, undated, accessed August 25, 2026; Google AI Max FAQ, undated, accessed August 25, 2026)
• ● Google improved privacy-compliant query reporting for searches from February 1, 2021 onward, even while later removing older terms that failed current thresholds. (Google Ads Developer Blog, published September 9, 2021)

Microsoft portability

• ● Microsoft announced an AI Max pilot in June 2026 with expanded queries, real-time creative, experiments, controls, and what it called transparent reporting. (Microsoft Advertising, published June 19, 2026)
• ● Accessible reporting says Microsoft made AI Max available globally on August 20, 2026 as an optional feature with three separately controlled components. Imported Google Search campaigns can carry AI Max settings. If the source Google campaign originated as DSA, Microsoft reverts it to DSA. Legacy Microsoft autogenerated text and predictive matching are mapped without switching on unrelated features. The underlying LinkedIn announcement could not be retrieved directly. (Search Engine Roundtable, published August 20, 2026; PPC News Feed, published August 21, 2026)
• △ Setting import improves configuration portability, but no source says Google model learnings, query histories, or creative-selection histories transfer to Microsoft. Microsoft's DSA reverse mapping can preserve a familiar structure, while different platform models still make outcomes non-portable.

Best steelman of Google's official rationale

△ Some opacity is inherent in machine-learned matching, and full query disclosure can conflict with user privacy. The proper comparison is not keyword control versus no control. It is whether the added source reporting, negatives, brand rules, URL rules, and experiments give advertisers enough outcome control to manage a model whose internal features cannot be expressed as a compact keyword list.

5.4 The forced-migration playbook

Rating: strong for the pattern, moderate for any claim that the pattern predicts performance or CPC

Strongest counter-argument

● Google does not eliminate the underlying Search campaign, negatives, brand controls, URL controls, reporting, or post-upgrade AI Max toggles in September. It is consolidating legacy switches into a common control surface. That is less coercive than a campaign-type retirement with no remaining functional opt-out, although new creation of the legacy configurations is permanently gone. (Google AI Max setup, undated, accessed August 25, 2026; Google Ads Developer Blog, published August 12, 2026)

Best steelman of Google's official rationale

△ Maintaining DSA, ACA, campaign-wide broad match, and AI Max as overlapping paths increases product complexity, inconsistent defaults, and duplicated development. Consolidation can give every legacy user the newer reports, experiments, brand controls, and URL controls while preserving the option to turn individual components off after conversion.

5.5 Defaults as adoption strategy

Rating: strong for the effect of defaults, moderate for the claim that adoption psychology is Google's disclosed motive

Supporting evidence

• ◆ A meta-analysis of 58 studies with 73,675 participants found a pooled default effect of d = 0.68, with a 95% confidence interval of 0.53 to 0.83. It also found substantial heterogeneity, several null results, and two negative effects. (Jachimowicz et al., Behavioural Public Policy, published online January 24, 2019)
• ◆ Madrian and Shea's canonical automatic-enrollment study found substantially higher 401(k) participation and strong persistence at default contribution and investment choices. (NBER working paper, published May 2000; journal version in Quarterly Journal of Economics, 2001)
• ● AI Max is on by default in the creation flow for new Search campaigns. Existing ACA and campaign-broad campaigns are placed into AI Max unless their owners act. The September window ends immediately before the Q4 retail period. (Google AI Max setup, undated, accessed August 25, 2026; Google Ads Developer Blog, published August 12, 2026)
• ● Google reported hundreds of thousands of AI Max advertisers in April and half a million in July. Smarter Ecommerce observed about 16% adoption among 600 active ecommerce accounts in March. These figures do not isolate opt-in versus default-driven adoption. (Google product blog, published April 15, 2026, updated June 11, 2026; Alphabet Q2 2026 earnings call, published July 22, 2026; Smarter Ecommerce, published March 23, 2026)
• △ Completing conversion just before Q4 increases the probability that the default is evaluated during a high-volume learning period and becomes embedded in peak-season operations. The timing is factual; the strategic intent is not disclosed.

Contradicting evidence and strongest counter-argument

• ● The migration defaults deliberately leave final URL expansion off for both September cohorts and text customization off for the broad-match cohort. Google is not applying the maximum-automation bundle to every eligible campaign. (Google Ads Developer Blog, published August 12, 2026)
• ● Current auto-apply recommendations are account-level opt-in and can be disabled at any time. The published recommendation list includes adding broad-match keywords and adding Dynamic Search Ads, but it does not establish that accounts using auto-apply are enrolled in campaign-level broad match, standalone ACA, or AI Max. (Google auto-apply recommendations help, undated, accessed August 25, 2026)
• △ A common control surface can be a product-maintenance decision even when it has a predictable default effect. Behavioral evidence shows that defaults change behavior; it does not prove that this was the reason chosen by Google executives.

Best steelman of Google's official rationale

△ Campaigns already using ACA or campaign-level broad match have affirmatively used one form of automation. Mapping them to the nearest AI Max settings, with final URL expansion kept off and post-conversion controls available, is a conservative continuity default rather than an arbitrary enrollment of all Search advertisers.

5.6 Regulatory context

Rating: weak as an explanation for the AI Max push

What the record says

• ● The December 5, 2025 final judgment in the U.S. search case follows findings that Google unlawfully maintained monopolies in general search services and general search text advertising. It requires qualified-competitor access to specified search index and user-side data, Search syndication, and a compliance regime. Section VI requires reporting of certain Search Text Ads auction changes to plaintiffs and the technical committee and requires public disclosure or an explanation for non-disclosure in specified circumstances. (U.S. v. Google final judgment, entered December 5, 2025; DOJ case page, updated August 17, 2026)
• ● The judgment also provides terms for Search Text Ads syndication intended to be nondiscriminatory and no more burdensome for eligible partners. It does not mention AI Max, ACA, DSA, campaign-level broad match, keyword portability, or generated assets. (U.S. v. Google final judgment, entered December 5, 2025)
• ● The 2026 proceedings are active: the court appointed initial Technical Committee members on January 21, plaintiffs filed their first compliance report on May 4, and the DOJ page lists status reports through August 14 and a July 28 appellate brief. Neither the May 4 compliance report nor the July 28 appellate brief contains the term “AI Max.” (DOJ search case page, updated August 17, 2026; first compliance report, filed May 4, 2026; appellate brief, filed July 28, 2026)
• ● In the separate ad-tech case, the April 17, 2025 liability decision found monopolization in publisher ad-server and ad-exchange markets and unlawful tying. The court did not accept the plaintiffs' proposed advertiser ad-network market. The DOJ case page was last updated December 26, 2025 and does not supply a 2026 final remedy. No primary 2026 final judgment or order was located for this dossier, so the current remedy outcome is left unresolved rather than inferred from secondary reports. (DOJ ad-tech decision, published April 17, 2025; DOJ ad-tech case page, updated December 26, 2025)

Supporting inference

△ The search judgment makes auction changes, syndication, and competitor access unusually salient. Keywordless matching and platform-only learning can raise practical questions about auditability and switching, even if those issues are not named in the order.

Strongest counter-argument

● No cited filing, judgment, compliance report, or ruling links AI Max to the litigation, treats AI Max as a remedy problem, or orders portability of advertiser campaign learnings. The ad-tech liability holding concerns publisher-side infrastructure, not the Search advertiser-control surface. (U.S. v. Google final judgment, entered December 5, 2025; DOJ ad-tech decision, published April 17, 2025)

Best steelman of Google's official rationale

△ The record is compatible with an ordinary product transition conducted under heightened oversight. Auction-change reporting may improve external supervision, while AI Max itself addresses new query formats and product simplification. It would be speculative to describe the migration as a response to, or evasion of, the cases.

6. Track D: exposure and stakes

6.1 What can be quantified

● No credible public estimate was located for the fraction of all Search campaigns or accounts using standalone ACA, campaign-level broad match, either feature, or both. Google has not published the number of September-eligible campaigns or accounts. This dossier does not estimate it.

6.2 Who carries the default

• ● The automatic September population is defined by configuration: Search campaigns still using the campaign-level broad-match setting or legacy standalone ACA. It is not defined in public documentation by business size, agency status, spend, or country. (Google Ads Developer Blog, published August 12, 2026)
• ● New Search campaigns encounter AI Max on by default in the current creation flow. That fact makes recommended or lightly managed setup paths relevant to exposure, but Google publishes no SMB-specific AI Max default-adoption rate. (Google AI Max setup, undated, accessed August 25, 2026)
• ● Auto-apply recommendations are opt-in at account level and can be turned off. The current published recommendation inventory does not show an AI Max recommendation or prove that auto-apply accounts enter the September cohort. “Accounts under auto-apply will be migrated” is therefore unsupported. (Google auto-apply recommendations help, undated, accessed August 25, 2026)
• △ Accounts with active specialists are more likely to review the email and manually select settings. Accounts whose legacy automation was enabled during earlier setup and left unattended are more likely to inherit the cohort default. No public dataset quantifies either group.

7. Contradiction log

8. Open questions not resolved from public sources

1. ● What fraction of all Search campaigns or accounts uses standalone ACA, campaign-level broad match, either, or both? No credible ecosystem-wide denominator was found.
2. ● Which default applies when one campaign is simultaneously in the ACA and campaign-level-broad cohorts? The August 12 mapping does not specify overlap precedence. (Google Ads Developer Blog, published August 12, 2026)
3. ● Is migration eligibility determined from an August 3 snapshot, at each campaign's migration timestamp, or by another freeze date? Public documents do not say.
4. ● Are existing generated ACA asset IDs and their asset-level histories retained, marked Removed and recreated, or re-associated under text customization? Google documents serving and reporting behavior after disablement, but not the migration's asset-identity mechanics. (Google text-customization instructions, undated, accessed August 25, 2026)
5. ● Does any learned model state transfer as a discrete object across the ACA or DSA mapping? Google promises historical settings and data for DSA, not the internal learning state. (Google product blog, published April 15, 2026, updated June 11, 2026)
6. ● Will Google leave post-conversion AI Max and component opt-outs available indefinitely? Current help permits them; no long-term product commitment was found. (Google AI Max setup, undated, accessed August 25, 2026)
7. ● What is current search-term-report cost and click coverage specifically for AI Max versus standard Search in a representative sample? No ecosystem-wide 2026 comparison was located.
8. ● What are the sample sizes, geographies, test lengths, assignment methods, confidence intervals, and dispersion behind Google's 7%, 14%, and 27% claims? Google does not disclose them in the cited materials. (Google product blog, published April 15, 2026, updated June 11, 2026; Google launch post, published May 6, 2025)
9. ● How many Search campaigns and accounts received the August 5 email, by country and advertiser segment? The public copies do not include a population count. (Search Engine Land, published August 5, 2026)
10. ● Does Microsoft's import preserve anything beyond settings, such as query history, asset history, experiments, or learning? Public rollout reporting does not say. (Search Engine Roundtable, published August 20, 2026)
11. ● No official public archive of the August 5 advertiser email was located. The occurrence and content are independently reported by Search Engine Land and PPC Land, while the August 12 Google developer post independently confirms the operative mechanics. (Search Engine Land, published August 5, 2026; PPC Land, published August 12, 2026; Google Ads Developer Blog, published August 12, 2026)
12. ● What is the operative 2026 remedy status in the separate ad-tech case? The DOJ page located for the dossier was last updated December 26, 2025, and no primary 2026 final judgment or order was found. (DOJ ad-tech case page, updated December 26, 2025)

9. Practitioner field guide: what to do before September 1

1. △ Export a dated campaign inventory with the two migration timestamp fields, current legacy settings, brand lists, URL controls, ad-group match settings, negatives, assets, and recent performance. The API fields and reports make this possible. (Google Ads Developer Blog, published August 12, 2026; Google AI Max API guide, updated August 19, 2026)
2. △ Decide campaign by campaign among three legitimate choices: turn off the legacy trigger before migration; enable AI Max manually with selected settings; or accept the cohort default. Do not use a single account-wide answer where brand, B2B qualification, catalog depth, and landing-page governance differ.
3. △ For broad-cohort campaigns, verify that text customization and final URL expansion remain off after the conversion. For ACA-cohort campaigns, verify that final URL expansion remains off. For both, inspect ad-group search-term matching and preserved brand lists against the August 12 mapping. (Google Ads Developer Blog, published August 12, 2026)
4. △ If testing, use experiments and judge account-level incrementality, not treatment-campaign ROAS alone. Monitor query source, search-partner segmentation, landing-page selection, conversion quality, branded and competitor leakage, generated assets, and total account revenue. The need follows directly from the cannibalization, invalid-traffic, and creative-test findings in section 4.
5. △ Treat DSA as a separate 2027 project. Inventory dynamic ad groups, page feeds, part-number or catalog use cases, unsupported targets, and legacy URL rules, but do not tell teams that DSA converts in September 2026. (Google Ads Developer Blog, published August 12, 2026)

10. Full source list with dates

Google product, support, developer, API, and Editor sources

1. Google, AI Max for Search launch announcement, published May 6, 2025.
2. Google Ads Developer Blog, AI Max open beta and API roadmap, published May 6, 2025.
3. Google Ads Help, Turn text customization on or off, undated, accessed August 25, 2026.
4. Google Ads Editor Help, Google Ads Editor version 2.10, undated, accessed August 25, 2026.
5. Google Ads Developer Blog, Google Ads API v21 announcement, published August 6, 2025. The URL slug says v19, but the page announces v21.
6. Google, Brandon Ervin, Upgrading DSA, ACA, and campaign broad match to AI Max, published April 15, 2026, updated June 11, 2026.
7. Google Ads API, Release notes, entries dated May 13 and August 19, 2026; page updated August 19, 2026.
8. Google Ads Developer Blog, Bob Hancock, Migrate campaign-level broad match and ACA settings to AI Max, published August 12, 2026.
9. Google Ads API, AI Max for Search getting started, updated August 19, 2026.
10. Google, AI Max testing and planning tools, published August 20, 2026.
11. Google Ads Help, Set up AI Max, undated, accessed August 25, 2026.
12. Google Ads Help, How AI Max works, undated, accessed August 25, 2026.
13. Google Ads Help, About AI Max, undated, accessed August 25, 2026.
14. Google Ads Help, AI Max frequently asked questions, undated, accessed August 25, 2026.
15. Google Ads Help, AI Max reporting, undated, accessed August 25, 2026.
16. Google Ads Help, About text customization, undated, accessed August 25, 2026.
17. Google Ads Help, About the broad match keywords campaign setting, undated, accessed August 25, 2026.
18. Google Ads Help, Search terms report, undated, accessed August 25, 2026.
19. Google Ads Help, Auto-apply recommendations, undated, accessed August 25, 2026.
20. Google Ads Developer Blog, Search terms report improvements, published September 9, 2021.
21. Google Ads blog, Close variants for all exact and phrase keywords, published August 14, 2014. The live page is no longer reachable; its full text is preserved as DOJ trial exhibit UPX8049 in U.S. v. Google (Bates USDOJ-GOOG-00187103).
22. Google, Exact close variants expansion, published March 17, 2017.
23. Google Ads Help, About close variants, undated, accessed August 25, 2026.
24. Google, Performance Max migration announcement, published January 27, 2022.

Alphabet filings and earnings sources

25. Alphabet, 2025 Form 10-K, filed February 5, 2026.
26. Alphabet, Q4 2025 earnings call, published February 4, 2026.
27. Alphabet, Q1 2026 earnings call, published April 29, 2026.
28. Alphabet, Q1 2026 Form 10-Q, filed April 30, 2026.
29. Alphabet, Q2 2026 earnings call, published July 22, 2026.
30. Alphabet, Q2 2026 Form 10-Q, filed July 23, 2026.

Independent measurement and practitioner sources

31. Lunio, AI Max invalid-traffic rates, updated August 14, 2026.
32. Lunio, Retail invalid-traffic report, updated August 14, 2026.
33. Smarter Ecommerce, Mike Ryan, AI Max for Google Search analysis, published March 23, 2026.
34. Smarter Ecommerce, DSA and AI Max podcast, published March 10, 2026.
35. Location3, AI Max franchise conversion experiment, published March 18, 2026.
36. Search Engine Land, Brad Geddes, Testing AI Max automated ad copy, published July 28, 2026.
37. Optmyzr, State of PPC study, published March 13, 2024.
38. Optmyzr, Paid search 2026 webinar takeaways, published April 20, 2026.
39. Seer Interactive, AI Overviews CTR update, published April 24, 2026.
40. Ahrefs, AI Overviews and clicks update, published February 4, 2026.
41. SE Ranking, AI Mode ads study, published July 14, 2026.
42. Seer Interactive, 2020 search-term visibility analysis, published September 2, 2020.
43. Marlin SEM, Missing search terms case audit, published July 9, 2025.
44. Seer Interactive, Phrase and broad-match-modifier expansion analysis, published August 2, 2019, updated November 15, 2019.
45. Tinuiti, Digital Ads Benchmark Report Q1 2023, publication date not displayed, accessed August 25, 2026.
46. PPC Land, AI Max industry tests, published August 17, 2025.
47. PPC Land, Independent tests and early Smec results, published November 8, 2025.
48. Reddit r/googleads, My experience using AI Max, displayed as two months old and accessed August 25, 2026.
49. Reddit r/googleads, DSA retirement discussion, displayed as four months old and accessed August 25, 2026.

Trade press and historical sources

50. Search Engine Land, Google to auto-upgrade some Search campaigns to AI Max, published August 5, 2026.
51. PPC Land, Google blocks new broad-match settings before migration, published August 12, 2026.
52. Search Engine Land, Google Ads Editor 2.10, published July 8, 2025.
53. Search Engine Roundtable, Microsoft Advertising AI Max global rollout, published August 20, 2026.
54. PPC News Feed, Microsoft AI Max global rollout, published August 21, 2026.
55. Search Engine Land, Phrase and broad-match-modifier same-meaning expansion, published July 31, 2019.
56. MarTech, Enhanced Campaigns early impact, published July 26, 2013.
57. Digital Commerce 360, Kenshoo Enhanced Campaigns analysis, published October 17, 2013.

Microsoft, behavioral science, and regulatory sources

58. Microsoft Advertising, Activate 2026 AI Max pilot summary, published June 19, 2026.
59. Jachimowicz et al., When and why defaults influence decisions: a meta-analysis, published online January 24, 2019.
60. Madrian and Shea, The Power of Suggestion: Inertia in 401(k) Participation and Savings Behavior, NBER working paper published May 2000; journal version published 2001.
61. U.S. Department of Justice, Search case page, updated August 17, 2026.
62. U.S. District Court for the District of Columbia, Final Judgment in U.S. v. Google, entered December 5, 2025.
63. U.S. Department of Justice, Ad-tech case page, updated December 26, 2025.
64. U.S. District Court for the Eastern District of Virginia, Ad-tech liability memorandum opinion, published April 17, 2025.
65. Plaintiffs, First status report on Google's compliance with the final judgment, filed May 4, 2026.
66. United States and co-plaintiff states, Response brief and opening brief on cross-appeal, filed July 28, 2026.

Bottom line

● On September 1, 2026 Google begins moving two legacy automation cohorts into a common AI Max control surface with cohort-specific defaults. ACA gains search term matching but keeps final URL expansion off. Campaign-level broad match gains the AI Max umbrella and keeps both creative automation and URL expansion off. DSA waits until February 2027. Owners can prevent the September mapping now and can alter the settings afterward under the current product. (Google Ads Developer Blog, published August 12, 2026; Google AI Max setup, undated, accessed August 25, 2026)

△ The strategic logic of adapting advertising to conversational AI search is well supported. The claims that Google is doing this chiefly to raise CPC, lock advertisers in, or evade regulatory pressure remain interpretations with moderate or weak support. Performance evidence is heterogeneous enough that controlled testing, account-level incrementality, and close query, URL, creative, and conversion-quality monitoring are more defensible than either blanket adoption or blanket rejection. (Alphabet Q1 2026 earnings call, published April 29, 2026; Smarter Ecommerce, published March 23, 2026; Lunio, updated August 14, 2026; Location3, published March 18, 2026; Search Engine Land creative tests, published July 28, 2026)