Adthena, a company that tracks online ads, found that far more brands are now paying to appear inside ChatGPT answers, with the weekly count of advertisers roughly two-thirds higher than eight weeks earlier. This matters to anyone who buys search ads, because it signals a fast-filling new ad channel and a reversal in what kind of search phrase triggers a paid link inside Google's AI summaries. The practical shift is that short, one or two word searches now account for over half of the ad appearances inside those summaries in every region measured, which is the opposite of what earlier data from the same firm had shown.

Adthena, the search intelligence platform, published its September 2026 monthly data pulse today, tracking three separate but related shifts in AI-driven advertising: a sharp rise in ChatGPT advertiser participation, a reversal in the query lengths that trigger ads inside Google's AI Overviews, and a look at which brands are capturing visibility across AI search surfaces in the United States, the European Union, Australia and Asia.

The report, an eight-page document distributed to press and summarized in a LinkedIn post from the company, tracked the number of unique advertisers appearing in ChatGPT ads on a weekly basis between July 9 and August 31, 2026. According to Adthena, weekly advertiser volume grew from 7,306 in the week of July 9 to 12,075 by August 31, an increase the company describes as roughly 65 percent across the eight-week window. The count peaked at 13,009 advertisers during the week of August 10, before dipping to just over 10,000 in the week of August 24 and then climbing back above 12,000 by the end of the month. Adthena frames the trajectory as a 1.78 times increase across the full period measured, from the lowest recorded week to the highest.

The timing of the publication places it squarely inside a period of rapid geographic expansion for OpenAI's advertising product. Sponsored placements reached 31 European markets on August 24, 2026, roughly midway through the window Adthena tracked, and the platform went on to add India and then seven Asian markets, pushing the publicly counted footprint past 60 countries by late September. A dip and recovery in the advertiser count around the August 24 European activation is visible in Adthena's own chart, though the company's published materials do not draw an explicit causal line between the market expansion and the mid-period fluctuation.

Advertiser count nearly doubles across eight weeks

The headline figure in Adthena's report is straightforward: a near-doubling of unique ChatGPT advertisers tracked weekly across a two-month span. The company's chart, titled "Ad presence is climbing weekly," plots the count from 7,306 in the week beginning July 9 through to 12,075 in the week beginning August 31, with the peak of 13,009 falling in between, during the week of August 10.

This is not the first time Adthena has published a running count of ChatGPT advertiser participation. The company launched what it called the ChatGPT Ads Share of Search Index in July 2026, at which point it had recorded 7,378 distinct advertisers across three markets - the United States, the United Kingdom and Australia - for the single week of July 13 to 20. That earlier figure sits almost exactly at the starting point of the new eight-week window Adthena has now published, suggesting a degree of methodological continuity between the two reports, even though the September pulse does not specify whether the 7,306-to-12,075 figures are drawn from the same three-market scope or from a broader set of regions.

The scale of the increase invites comparison with the pace of OpenAI's own geographic expansion during the same period. ChatGPT Ads had reached nine publicly counted markets by August 17, 2026, when Brazil and Mexico activated. The platform then added its largest single expansion to date on August 24, when sponsored placements began appearing across 31 European countries, a rollout OpenAI itself had confirmed on August 18. India followed on August 29, and by August 31, OpenAI stated that ChatGPT Ads operated in more than 40 countries, alongside a disclosure that the advertising business had reached a $1 billion annualized revenue run rate in under 200 days, according to Digiday's reporting, which PPC Land covered at the time.

Set against that expansion timeline, the mid-period dip Adthena recorded - from the 13,009 peak in the week of August 10 down to just over 10,000 by August 24 - falls immediately before the European market activation date, and the subsequent recovery to 12,075 by August 31 tracks closely with the days following that expansion. Adthena's published materials do not explain the dip, and no further detail on its cause appears in the documents reviewed for this article.

A market still finding its shape

Adthena's own historical reporting provides useful context for how quickly the underlying channel has grown. The company's earlier index recorded a claim that ad placements on the ChatGPT platform had grown 97 times between April and June 2026, a figure the firm published alongside its first weekly advertiser count in July. Sensor Tower's later analysis, examined separately by PPC Land in its coverage of the $1 billion run rate, documented a parallel shift in advertiser mix toward financial services spending, which reportedly tripled over the same period the run rate milestone was reached.

The advertiser count Adthena tracks is a measure of unique participation, not spend or impression volume, and the company's own reports have repeatedly emphasized that its methodology involves monitoring paid placements across live ChatGPT sessions rather than drawing on OpenAI's internal reporting. That distinction matters because ChatGPT's own Ads Manager, as PPC Land has previously reported in connection with Adthena's Dentsu partnership, surfaces cost-per-click, impressions and click-through rates as first-party performance metrics that describe outcomes for a given advertiser's own campaigns, without providing a competitive or market-wide view. Third-party measurement firms including Adthena have positioned themselves as filling that visibility gap, though no independently audited share-of-voice standard yet exists for the channel.

AI Overview ad queries reverse toward short-tail searches

The second major finding in Adthena's September pulse concerns a different platform entirely: Google's AI Overviews. The report states that one-to-two word queries now command over half of AI Overview ad appearances in every market measured, a finding the company frames as a marked shift from patterns observed in June 2026.

The regional breakdown, presented across four markets in Adthena's report, shows the following distribution of AI Overview ad appearances by query word count:

In the United States, out of 288.6 million total AI Overview ad appearances, 62.9 percent came from one-to-two word queries, 33.1 percent from three-to-four word queries, 3.7 percent from five-to-six word queries, and 0.4 percent from queries of seven words or more. The European Union showed a similar pattern across 110.8 million appearances: 62.4 percent from one-to-two word queries, 34.3 percent from three-to-four word queries, 3.1 percent from five-to-six word queries, and 0.2 percent from longer queries. Australia, with 50.5 million appearances, recorded 56.5 percent from the shortest query band, 39.6 percent from three-to-four words, 3.8 percent from five-to-six words, and 0.1 percent beyond that. Asia showed the most pronounced concentration: of 13.6 million appearances, 74.4 percent came from one-to-two word queries, 23.9 percent from three-to-four words, 1.7 percent from five-to-six words, and effectively none from longer searches.

According to Adthena, the finding represents an opportunity signal for advertisers: brands optimized for short, high-intent queries are now positioned to capture AI Overview volume, whereas the prevailing assumption in the industry - shaped in part by Adthena's own earlier research - had pointed in the opposite direction.

A documented reversal from April's findings

This is where the September pulse becomes notable for anyone who has followed Adthena's output over the preceding months, because it directly contradicts the company's own prior published conclusions. In April 2026, Adthena published what it described as a 29 million query report, which PPC Land covered in detail at the time. That report stated that the 60-percent-plus concentration of AI Overview ad appearances fell on three-to-four word queries, explicitly challenging what the company called the conventional assumption "that AI search is primarily a long-tail phenomenon." The April report noted that industry wisdom held longer, more conversational queries would dominate AI ad auctions, given that AI systems are supposedly built to handle exactly that kind of input, and that the data at the time contradicted this in the opposite direction from what the September figures now show: over 60 percent of appearances then fell into the three-to-four word band, not the one-to-two word band the new report identifies as dominant.

A subsequent Adthena report, covering June 2026 data and examined in PPC Land's coverage of zero ChatGPT ad share for UK advertisers, reinforced the same three-to-four word conclusion, finding that band capturing between 57.4 and 71.2 percent of ad appearances across the three markets examined at that time. That June report suggested that mid-length, moderately specific searches, rather than either very short or very long ones, were where AI Overview ad auctions concentrated.

The September pulse now reports a different distribution entirely, with the shortest query band - one to two words - taking the majority share across every region measured, and the three-to-four word band that previously dominated now sitting in second place at roughly a third of appearances in most markets. Adthena's own materials describe this as a shift from June, but the underlying mechanism driving the reversal is not addressed in the documents reviewed for this article. Whether the change reflects an alteration in how Google selects queries eligible for AI Overview ad placement, a shift in the composition of queries reaching AI Overviews generally, or a change in Adthena's own measurement methodology across the two reporting periods is not stated.

The finding also arrives against the backdrop of public comments from Google executives on query length trends elsewhere in the company's AI search products. Liz Reid, Google's search chief, said in comments PPC Land reported in April 2026 that the shift to longer, natural-language queries was "already happening at scale" and that the frequency of ads appearing inside AI Overviews grew from 0.052 percent in November 2025 to 0.12 percent by April 2026. Those comments concerned overall query behavior and ad frequency rather than the specific word-count distribution of ad appearances that Adthena's reports track, and Reid's remarks predate the September findings by roughly five months.

Regional advertiser concentration shows Booking.com as the outlier

Adthena's report also breaks down which advertisers are capturing the largest share of AI Overview ad appearances by region, and the pattern that emerges points to one company standing apart from an otherwise locally-fragmented picture.

In the United States, Carvana leads with 1.2 percent of total appearances, followed by Booking.com at 1.0 percent, Toyota at 0.9 percent, Mercado Livre at 0.8 percent, Walmart at 0.8 percent, and Expedia at 0.8 percent. In the European Union, Booking.com tops the list at 2.9 percent, ahead of Amazon UK at 1.8 percent, GetYourGuide also at 1.8 percent, eBay UK at 1.8 percent, Argos at 1.5 percent, and Backmarket at 1.4 percent. Australia's top advertiser is Dan Murphy's at 4.3 percent, followed by Canstar at 2.0 percent, Finder at 1.9 percent, BWS at 1.6 percent, Amazon Australia at 1.4 percent, and Woolworths at 1.4 percent. In Asia, Hostinger leads at 3.6 percent, with Shopee Singapore at 3.1 percent, Lenovo also at 3.1 percent, Shopee Indonesia at 2.9 percent, Booking.com at 2.8 percent, and Trip.com at 2.8 percent.

According to Adthena, Booking.com is the only brand appearing in the top five across three separate markets at once - the United States, the European Union and Asia - a distinction the report frames as an exception to an otherwise strongly localized pattern. The company's materials state plainly that "every other category belongs to whoever owns the local market," a characterization that fits the data: Carvana's US lead does not extend elsewhere, Dan Murphy's dominance in Australian retail has no analog in the other three regions, and Hostinger's position atop the Asian rankings does not reappear in any other market's top six.

The finding echoes an earlier Adthena report that examined ChatGPT ad category concentration specifically. That analysis, covering the European launch period in August 2026 and detailed by PPC Land, found that Expedia was among the confirmed early ChatGPT advertisers, alongside Best Buy, and that a narrow band of broad-catalogue advertisers absorbed most of the early visibility in each new market as it opened. The travel category's persistent visibility across both AI Overview ads and ChatGPT ads, spanning multiple Adthena reports published months apart, suggests a category with unusually durable performance in AI-driven search advertising generally, independent of which specific AI platform is measured.

Retail category leaders vary sharply by market and vertical

Adthena's report extends its regional breakdown into two specific retail sub-verticals: electronics and appliances, and apparel and accessories, measured by share of clicks rather than AI Overview ad appearances specifically.

In electronics and appliances, Temu leads the United States outright at 28.3 percent of clicks, ahead of Best Buy at 9.15 percent, Walmart at 8.57 percent, Home Depot at 7.1 percent, and Apple at 5.96 percent. In the United Kingdom, the order shifts to favor a domestic incumbent: Argos leads at 17.97 percent, with Amazon UK at 12.0 percent, Temu at 7.89 percent, Currys at 7.35 percent, and eBay UK at 4.09 percent. Australia shows Temu again in first place at 14.25 percent, followed by Amazon Australia at 9.63 percent, The Good Guys at 8.12 percent, Kogan at 6.72 percent, and Appliances Online at 6.21 percent.

Adthena characterizes Temu's position as an opportunity signal, noting the company leads the US market outright and places top three in all three markets measured, while local incumbents such as Argos and Best Buy continue to hold their home markets.

The apparel and accessories category tells a markedly different story, with no single brand crossing the 9 percent threshold in any market and no name repeating across regions. In the United States, Lululemon leads at 8.8 percent, followed by Nike at 6.73 percent, Birkenstock at 4.21 percent, Coach at 3.65 percent, and Victoria's Secret at 2.59 percent. The United Kingdom's leader is Shein at 4.66 percent, with Marks and Spencer close behind at 4.65 percent, Asos at 3.67 percent, Next at 3.2 percent, and Sainsbury's at 2.07 percent. Australia's top apparel brand is Coach at 7.96 percent, ahead of Temu at 6.06 percent, David Jones at 5.18 percent, Shein at 3.75 percent, and Myer at 3.22 percent.

According to Adthena's own characterization of this category, apparel has no global winner - only local leaders, a framing the company draws directly from the data: Lululemon's US position does not transfer to the UK or Australia, and Shein's UK lead sits alongside a considerably smaller Australian share for the same brand.

ChatGPT's European expansion provides the backdrop

The timing of Adthena's advertiser-count findings intersects closely with a period of geographic expansion that PPC Land has tracked in granular detail throughout August and September 2026. OpenAI's advertising pilot began on February 9, 2026, restricted to logged-in adult users in the United States on Free and Go subscription tiers, with paid subscription tiers and users under eighteen excluded from the outset.

From that narrow starting point, the geographic footprint widened in a sequence of discrete steps. Brazil and Mexico activated on August 17, 2026, bringing the publicly counted market total to nine. Sponsored placements then began appearing across 31 European markets on August 24, described by OpenAI as its largest expansion to date, a characterization first confirmed on August 18, six days before the ads themselves went live. India followed on August 29, completing what OpenAI itself described, according to a LinkedIn post from Benji Shomair examined in PPC Land's coverage, as 32 new markets added in five days and taking the publicly counted total to 41.

On August 31, 2026, OpenAI stated that ChatGPT Ads operated in more than 40 countries and opened self-service Ads Manager access across India, Europe, the Middle East and North Africa. The same week, according to CNBC's reporting examined in PPC Land's coverage of David Dugan's comments, OpenAI disclosed that advertising inside ChatGPT had reached a $1 billion annualized revenue run rate, a milestone the company presented as evidence of a diversified business model ahead of a prospective initial public offering.

The expansion continued past the boundaries of Adthena's measurement window. Seven additional Asian markets went live in the days that followed, according to PPC Land's most recent reporting, taking the publicly counted total past 60 countries by late September 2026. That same report noted a discrepancy in publicly available figures regarding minimum campaign spend requirements and currency coverage for the newest markets, details that remained unresolved as of the most recent PPC Land coverage.

Access to ChatGPT Ads has, throughout this expansion, run primarily through OpenAI's own Ads Solutions team and through agency and technology partners, with self-service access arriving in stages and market by market. Adform announced on September 10, 2026, that it had been selected as one of the technology platform partners supporting the European rollout specifically, giving the integrated advertising platform's clients what PPC Land's coverage described as a managed pathway into OpenAI's advertising system, with OpenAI Ireland Limited serving as the controller for users in the European Economic Area and Switzerland.

DMEXCO and the wider industry conversation

The publication of Adthena's September pulse arrives in the same week as DMEXCO, the trade fair held at the Koelnmesse grounds in Cologne on September 23 and 24, 2026. OpenAI's David Dugan attended the event, according to PPC Land's reporting, and hosted a talk alongside Ulrich Klenke, Chief Brand Officer at Deutsche Telekom. That same week, the European Commission designated ChatGPT a very large online search engine under the Digital Services Act, following OpenAI's declaration of 159.1 million average monthly users in the European Union, with additional obligations including advertising transparency duties falling due by the end of December 2026.

Broader context for AI search advertising measurement

The findings in Adthena's September pulse sit within a longer arc of the company's own reporting on AI-driven search advertising, stretching back to November 2025, when Adthena became the first platform to publicly document ads appearing inside Google AI Overview search results at all. That original detection covered just 13 instances across 25,000 monitored search results pages, a frequency of 0.052 percent, according to the company's announcement at the time.

Adthena expanded its monitoring infrastructure specifically for ChatGPT in May 2026, launching what it described as the first intelligence platform built for the channel, tracking placements across more than 300,000 daily prompts, according to PPC Land's coverage of that launch. The company followed with a free migration tool called ChatGPT AdBridge in April 2026, designed to port existing Google Ads campaigns onto OpenAI's platform, at a point when the pilot had surpassed 600 participating advertisers, as PPC Land reported.

The company's commercial relationships in this space have also drawn scrutiny. Adthena partnered with Dentsu in July 2026 to measure UK ChatGPT cost-per-click volatility, a partnership PPC Land examined critically at the time, noting that the arrangement placed Adthena in the position of measuring the market performance of its own new commercial partner's clients, using its own proprietary methodology, in a channel where no independently audited share-of-voice standard exists.

None of this history changes the substance of what Adthena's September pulse reports, but it does establish a pattern worth noting for anyone evaluating the reliability of the query-length reversal specifically. Adthena has published at least three distinct reports on AI Overview ad query-length distribution across roughly five months - April, June, and now September 2026 - and the September figures directly contradict the two that preceded them. The company's own report characterizes the shift as a change from June rather than as a correction of the April findings, though the two conclusions, read together, describe the same underlying phenomenon measured at different points in time with directly opposing results.

Timeline

  • November 24, 2025 - Adthena becomes the first platform to detect ads inside Google AI Overviews, finding 13 instances across 25,000 monitored searches, a frequency of 0.052 percent
  • February 9, 2026 - OpenAI begins serving ads to logged-in adult users on ChatGPT's Free and Go subscription tiers in the United States
  • April 2026 - Adthena publishes a 29 million query report finding three-to-four word queries drive over 60 percent of AI Overview ad appearances
  • April 27, 2026 - Adthena launches ChatGPT AdBridge, a free tool migrating Google Ads campaigns onto ChatGPT
  • May 11, 2026 - Adthena launches its dedicated ChatGPT Ads intelligence platform, tracking over 300,000 daily prompts
  • June 2026 - A follow-up Adthena report confirms three-to-four word queries still dominate AI Overview ad appearances, at 57.4 to 71.2 percent across three markets
  • July 13-20, 2026 - Adthena's first weekly ChatGPT advertiser index counts 7,378 distinct advertisers across three markets
  • Week of July 9, 2026 - Weekly ChatGPT advertiser count begins the tracked eight-week period at 7,306
  • July 23, 2026 - Adthena partners with Dentsu to measure UK ChatGPT cost-per-click volatility
  • August 17, 2026 - Brazil and Mexico activate, bringing ChatGPT Ads to nine publicly counted markets
  • August 21, 2026 - Adthena publishes its European launch analysis drawn from nearly 850,000 AI search queries
  • Week of August 10, 2026 - Weekly ChatGPT advertiser count peaks at 13,009
  • August 24, 2026 - ChatGPT Ads reaches 31 European markets, OpenAI's largest expansion to date
  • Week of August 24, 2026 - Weekly ChatGPT advertiser count dips to just over 10,000
  • August 29, 2026 - ChatGPT Ads goes live in India, taking the publicly counted total to 41 markets
  • August 31, 2026 - OpenAI reports ChatGPT advertising reaching a $1 billion annualized revenue run rate and expands to more than 40 countries
  • Week of August 31, 2026 - Weekly ChatGPT advertiser count reaches 12,075 to close the tracked period
  • September 10, 2026 - Adform confirms its selection as a technology platform partner for the European ChatGPT Ads rollout
  • September 23-24, 2026 - DMEXCO trade fair takes place in Cologne; ChatGPT Ads reaches more than 60 countries following the addition of seven Asian markets
  • September 23, 2026 - Kite Hill PR notifies PPC Land of Adthena's new data pulse on behalf of the company
  • Today, September 25, 2026 - Adthena publishes its September 2026 monthly AI data pulse, reporting the 65 percent ChatGPT advertiser increase and the AI Overview query-length reversal

Summary

Who: Adthena, the London-based search intelligence platform, alongside OpenAI, the operator of ChatGPT's advertising network, and Google, whose AI Overviews feature is the subject of the query-length findings. The report affects paid search professionals, media buyers and marketers evaluating budget allocation across AI-driven search advertising channels.

What: Adthena published its September 2026 monthly AI data pulse, reporting a 65 percent increase in weekly unique ChatGPT advertisers - from 7,306 to 12,075 over eight weeks, peaking at 13,009 - alongside a finding that one-to-two word queries now command over half of Google AI Overview ad appearances in every region measured, reversing the three-to-four word dominance the same company had documented in April and June 2026. The report also detailed regional advertiser concentration, identifying Booking.com as the only brand appearing among the top five AI Overview advertisers across three separate markets.

When: Adthena's report tracks data from July 9 to August 31, 2026, and was published today, September 25, 2026.

Where: The findings span the United States, the European Union, Australia and Asia, corresponding with a period in which ChatGPT Ads expanded from nine to more than 60 publicly counted countries.

Why: The near-doubling of ChatGPT advertiser participation signals rapid commercial adoption of a channel that reached a $1 billion revenue run rate the same week its European expansion peaked, while the reversal in AI Overview query-length patterns directly contradicts the same firm's own prior published research, raising unanswered questions about what changed in Google's ad-serving mechanics or in Adthena's measurement methodology between June and September 2026.