AI Overviews Are Auto-Expanding Into AI Mode -- What Changed

There is a feature change in Google's AI Overviews that has received almost no attention in AEO coverage. As of September 2026, Google is removing the "Show More" button from AI Overviews on some queries and replacing it with auto-expanded responses -- responses that reach AI Mode depth without the user clicking anything.

The business implication is significant. AI Mode and AI Overviews have always had different citation architectures. They pull from different sources, at different depths, using different signal weights. That gap is now collapsing on an expanding share of queries, and it changes who gets cited.

AI Mode and AI Overviews Are Not the Same Thing

This context is necessary because most AEO advice treats them as interchangeable.

In our May 23, 2026 investigation into AI Mode citation architecture (Scout session 26, `knowledge/platform-citation-behaviors.md`), we pulled Ahrefs' analysis of 540,000 query pairs run simultaneously across AI Mode and AI Overviews. The URL overlap between the two surfaces: 13.7%.

That means 86.3% of the URLs appearing in AI Mode answers are different from the URLs appearing in AI Overviews answers for the same queries, on the same Google infrastructure. The two surfaces are drawing from almost entirely different citation pools.

Why? AI Mode uses query fan-out -- it decomposes a single user query into multiple sub-queries, retrieves source content for each independently, then synthesizes a multi-source answer. AI Overviews in its standard form generates a shorter, more direct response with fewer cited sources and less cross-referencing. The depth difference produces the source difference.

What the Expansion Changes

In our September 18, 2026 platform update (Scout session 142, `knowledge/platform-citation-behaviors.md`), we documented a structural change Google is rolling out: AI Overviews are now auto-expanding into AI Mode-style responses for a subset of queries without user action. Google's "Show More" button -- which previously allowed users to voluntarily expand a short AI Overview into a longer, AI Mode-depth answer -- is being removed for those queries. The expanded, multi-source response now generates by default.

The implications for citation coverage:

**Queries that previously generated short AI Overviews now generate AI Mode-depth answers.** The pool of queries receiving AI Mode-style citation treatment is expanding without users having to opt in. For businesses that appear in short AI Overviews but not in AI Mode's deeper citation set, the expansion represents a new gap -- they can lose citation presence on queries where they previously appeared, simply because the response format deepened.

**For businesses in AI Mode's citation set, the expansion means more query volume reaches them without users needing to click.** A business cited in AI Mode responses is now getting that exposure on a broader query set.

Google has not published the criteria for which queries trigger auto-expansion. Coverage as of session 142 describes the rollout as selective, without a category breakdown. Based on the pattern from other AI Mode changes, home services and local queries (where fan-out sub-queries across services, geography, and reviews are most useful) seem like early candidates.

The Citation Architecture That Now Matters More

Understanding what AI Mode actually cites is more important under auto-expansion, because the same signals that determine AI Mode presence now determine AI Overviews presence on expanded queries.

Two vault findings are relevant here.

In our June 26, 2026 update to AI Mode local citation architecture (Scout session 59, `knowledge/platform-citation-behaviors.md`), we documented an SE Ranking study of 1.3 million AI Mode citations across 68,313 keywords. By February 2026, the composition of Google's own self-citations inside AI Mode had shifted substantially:

- In mid-2025: 97.9% of Google's AI Mode self-citations pointed to Google Business Profiles - By February 2026: only 41% of those Google self-citations pointed to GBP; the remaining 59% pointed to traditional organic content pages

GBP used to dominate AI Mode for local queries. As of early 2026, AI Mode was increasingly citing organic content alongside GBP -- and that balance has continued to shift.

A Moz study of 40,000 keywords from the same February 2026 period found that 88% of AI Mode citations do NOT match the URLs in the top-10 organic results for the same keyword. AI Mode is not pulling from your top-10 SEO rankings. It is pulling from the fan-out sub-query space, which includes directories, comparison articles, review sites, and specialized content pages that may rank on sub-queries you have never optimized for.

The Practical Change for AI Visibility Work

A business that has optimized for traditional AI Overviews -- focused on appearing in short, direct responses -- now needs to understand whether its citation presence extends into the AI Mode-depth version of those same queries.

The two surfaces share 13.7% of their citation URLs. That means a strong AI Overviews position does not predict AI Mode presence. If the query your business appears in is one Google is expanding to AI Mode depth, the citation source pool is almost entirely different.

What the vault data suggests for businesses that want to appear in both surfaces:

**GBP alone is no longer sufficient for AI Mode.** The February 2026 data shows AI Mode moved toward organic content. A business with a well-optimized GBP but thin website content -- or no presence in the directory and comparison articles feeding fan-out sub-queries -- will have a gap that auto-expansion makes visible.

**Fan-out sub-query coverage matters.** If your business appears in Yelp, Foursquare, Thumbtack, and relevant comparison pages for your category, you are building presence in the source pool that AI Mode's fan-out is pulling from. If your presence is limited to GBP and your own website, the fan-out coverage is narrower.

Running a Signal Check gives you a reading of your current citation presence across AI surfaces, including Gemini-powered Google responses. If you want to understand where your AI Mode gap sits specifically, that baseline is the starting point.

The auto-expansion rollout is still selective. But the direction of the change is clear: the boundary between AI Overviews and AI Mode is collapsing, and the citation architecture that governs AI Mode -- multi-source, fan-out driven, organic content-weighted -- is the architecture that governs more queries every month.