Through the first half of 2026, Google steadily expanded AI Overviews coverage deeper into health, finance, and product comparison queries — verticals that had been comparatively cautious since the feature’s general availability rollout in May 2024. By April 2026, third-party trackers put AI Overviews on roughly 48% of informational queries (BrightEdge), with health near saturation: BrightEdge measured AI Overviews on 88% of healthcare queries and 81% of symptom queries by early 2026.
A year earlier that informational-query figure sat far lower — BrightEdge logged a 58% expansion of AI Overviews coverage across nine industries between February 2025 and February 2026. The growth curve is steepening, not flattening.
What’s actually new
Three categories that were historically slower to trigger AI Overviews are now firing far more consistently:
- Health “is X safe” queries (medical YMYL, where BrightEdge now measures the highest AIO trigger rates of any YMYL category)
- Finance “best Y account” queries (finance educational content was tracking 55–70% AIO presence in early 2026 and climbing)
- Product comparison queries with three or more named products (AI Overviews reached ~14% of shopping queries by March 2026, a 5.6x jump from November 2024)
Cyrus Shepard has documented the AI-citation mechanics behind this shift in depth — his May 7, 2026 Zyppy Signal analysis distilled findings from 54 experiments, patents, and case studies on what earns citations inside AI surfaces.
What it means for organic traffic
Sistrix’s clickstream analysis (drawn from more than 100 million keywords) measured the impact on search-result CTR for queries that trigger AI Overviews:
- Top organic result: CTR roughly halved — Sistrix’s DACH data showed position 1 falling from ~27% (no AIO) to ~11% (with AIO), a ~59% decline
- In absolute terms: Sistrix estimated German sites alone lose ~265 million clicks per month to AI Overviews
When AI Overviews appear, the share of searches ending without any click to an external site rises sharply — SparkToro/Datos clickstream data puts the no-click rate at ~83% on AIO queries (versus ~65% of all Google searches).
For health and finance publishers, this is a meaningful demotion, and the newly-affected YMYL verticals are squarely in the path of it.
Who is being cited inside the AI Overview
The citation footer of the AI Overview is the new top spot. Across third-party citation studies in 2026, a consistent set of health domains dominates the health vertical:
- Healthline, Cleveland Clinic, Mayo Clinic, and WebMD rank among the most-cited health domains in Google AI Overviews (Ahrefs’ June 2026 most-cited-domains analysis)
- Institutional and government-affiliated sources — Mayo Clinic, Cleveland Clinic, NIH, PubMed, the NHS — carry outsized weight relative to their organic footprint
- Across AI platforms more broadly, ChatGPT leans heavily on Mayo Clinic and Healthline, while Gemini favors NIH and Cleveland Clinic
The pattern: institutional and university-affiliated sources are weighted heavily alongside the established commercial health publishers in the medical vertical. WebMD (whose parent Internet Brands is led by CEO Bob Brisco) remains among the top-cited commercial sources, but the relative lift now accrues to institutionally-backed domains.
The defensive playbook
For publishers in the newly-affected verticals, three things to do this week:
- Pull a SERP snapshot for your top 100 head queries. If they’ve started triggering AI Overviews, that’s where to focus.
- Add author + medical reviewer credentials to YMYL content. Health AIOs are heavily favoring credentialed bylines.
- Look at your citation metadata. Sources cited in the AI Overview footer all share three things: clear publication date, named author or organization, and consistent canonical URLs.
The expansion is going to keep going — legal and finance categories were still climbing toward 80–90% AIO presence as of mid-2026. Plan accordingly.