Is AI engine exposure associated with rising branded search? A two-source study of 347 US brands, 2015-2026, with a pre-specified analysis plan

Ranking Atlas Working Paper RA-WP-2026-02. Not peer reviewed. Background. Practitioners widely describe AI engines as a branding channel. In this account, users meet brands in AI answers and then search for them by name on Google. If this holds at scale, US branded search should rise relative to non-branded search as AI adoption grows, and brands that AI engines mention more should gain more. Methods. We froze an analysis plan with three hypotheses (H1a-c) before collecting outcome data, and later added four amendments; two of them added tests of AI recommendation (H2) and recommendation position (H3) after earlier results had been seen. The sample was 347 US brands in 14 categories plus 140 non-branded control terms. AI exposure, top-3 rate and position tier came from 420 ChatGPT and Gemini responses to category prompts (Gemini answers were not US-localised). Outcomes were US branded search in Google Trends (2015-2026) and Google Ads (2022-2026), with pre-AI placebo tests, split-half checks, Holm correction and equivalence tests. Growth is reported in percentage points (pp) of annual growth (log points x 100). Results. No H1 test was supported. The exposure gradient was +2.13 pp per year per SD in Trends (95% CI -0.82 to 5.08) and +2.28 in Ads (95% CI -1.15 to 5.72), and equivalence to zero was not established, so an effect of 2 pp cannot be ruled out. Branded search did not gain share against non-branded search in either source. Brands named among the first three in at least 20% of AI answers grew faster: +7.13 pp per year against matched brands in Ads (95% CI 2.10 to 12.36), with no significant gap in 2015-2022 Trends growth, but the gap was not stable over time. Ads growth was ordered by position tier (+5.42 pp per tier step), but before ChatGPT the ordering tended to run the other way. Under the pre-specified rules both results are inconclusive, and whether first position beats positions 2-3 could not be resolved (11 brands in first position). Conclusions. We found no confirmatory evidence that AI adoption has raised US branded search overall. Brands that AI answers name early show faster recent branded growth, but the top-3 gap was unstable over time and the position ordering tended to reverse a pre-2022 pattern. These patterns are compatible with a modest aggregate echo of individual-level effects reported by industry studies, and also with AI engines favouring already-popular brands. The study does not establish causation.