The SEMPITE AI Visibility Index: do AI assistants recommend the businesses Google ranks first? (2026 Q3)

A recurring measurement of whether AI assistants name the local businesses that Google Maps ranks in its top three. Quarterly editions are released as new versions of this record.

Sample. 50 US local markets, five service categories (plumber, dentist, personal injury lawyer, real estate agent, HVAC contractor) across ten large cities, measured in August and September 2026 against three engines: gpt-4o-mini with web search off, the same model with web search on, and Google AI Mode. 150 business-engine observations per engine-run.

Selected findings, share of Google top-3 businesses NOT named in the AI answer (95% Wilson intervals).

• ChatGPT, no web search, September 2026: 95.3% invisible (90.7 to 97.7). August 2026: 96.0% (91.5 to 98.2).
• ChatGPT with web search on, September 2026: 89.3% invisible (83.4 to 93.3).
• Google AI Mode, September 2026: 68.0% invisible (60.2 to 74.9).
• Every engine answered with specific named businesses in all 50 markets. The businesses named were mostly not the ones Google ranks first.

Contents. Every stored AI answer in full with the prompts used, one row per month-market-business-engine observation, the dependency-free matching code that can be re-run to regenerate the results, the scoring code, and a methods document with an eleven-point limitations section.

Two things to read before citing. The matching rule errs toward counting a mention, so published invisibility rates are conservative. Figures published before 17 September 2026 used an earlier rule that counted generic words such as the city or the trade as a mention of the business, and substantially overstated visibility; limitation 9 documents the correction.

Write-up: sempite.com/research/ai-visibility-index/. Data CC BY 4.0, code MIT.