AI Max, Google’s new automation layer for Search campaigns, is designed to help performance marketers move from keyword- to intent-based targeting in just a few clicks. According to Google, advertisers who use AI Max will see 14% more conversions or conversion value at a similar return on their ad spend.
But this might not be the full picture. Early adopters have found that AI Max risks showing your ads for unwanted search terms, potentially triggering advertising turf wars with your competitors. And the complications don’t end there.
New Lunio client data indicates that AI Max can significantly increase invalid traffic (IVT) rates. Our client saw a 35% increase in IVT in one month with AI Max activated, leading to a surge in wasted ad spend.
Here, we share our findings and data analysis to highlight the potential impact of AI Max on your IVT rates, why this matters, and what you can do to mitigate the negative impact of AI Max on your campaigns.
The impact of AI Max so far
AI Max is a natural progression in terms of Google’s push towards automation and AI in performance marketing. Google claims it can “power up your performance by expanding your reach into new queries that you weren’t accessing before.”
There’s no question that AI Max can expand your reach. But whether it expands into the areas you want is another matter. Mike Ryan, head of ecommerce insights at Smarter Ecommerce, shared data showing that brand terms for a single competitor accounted for 69% of total impressions in an AI Max-enabled campaign. Mike estimates that including all competitor terms would increase the impression share to more than 80%.
Creating conflict between you and your competitors isn’t just bad for your brand. It can lead to escalating costs, thanks to increased click competition and a heightened risk of clicks from irrelevant users who are actively searching for other brands.
Competitor search term impressions is just one concern marketers have highlighted with AI Max. Others have reported that AI Max is generating conversions that cost more than traditional Search campaigns, with We Know Growth’s Matthew Gatley reporting CPAs that are 13.6% higher than the campaign baseline:
This contradicts Google’s claim that brands will see uplift at a similar CPA or ROAS to their current cost (although the datasets may not be directly comparable). Our data suggests why your acquisition costs may not be as low as you’d like.
Below, we share data that reveals a link between AI Max and invalid traffic, and how this can lead to escalating costs and wasted ad spend.
Our data: AI Max & invalid traffic
We’ve analyzed early preliminary data from one of our clients: a business in the luxury retail space, where the entry level price point for their products is around £500, increasing to around £10,000 at the higher end.
The brand had been using Lunio’s ad traffic verification platform for 12 months prior to January 2025. With Lunio, they cut their overall average IVT rate in half across their Google Search campaigns, reducing it from just over 7% to a stable baseline average of 3.7%. From January to May 2025, the brand maintained this baseline average IVT rate, as you can see in the chart below.
In May 2025, the brand took part in the AI Max open beta, during which AI Max was enabled on 404 of their Search campaigns. 491 campaigns were unchanged, and ran without AI Max, giving us unique insights into the impact of AI Max on IVT rates.
Our data science team performed statistical analysis across all campaigns to assess the impact of enabling AI Max on IVT. In the chart above, you can see the actual rate of IVT — the blue line — starts to increase when AI Max is activated. (The red line denotes the expected rate of IVT had AI Max not been activated.)
Here’s what we found:
- For Search campaigns with AI Max enabled, the average IVT rate rose from 3.7% to 5%, with highs of up to 6% reported.
- The change in the baseline IVT rate (from 3.7% to 5%) represents a 35% increase in the amount of IVT AI Max-enabled campaigns were exposed to.
- For accounts spending large amounts (like this client), this represents a significant increase in wasted ad spend.
Our data science team explains how they analyzed the results:
“We performed statistical analysis on both sets of campaigns to assess the impact of AI Max. We started with an initial difference-in-difference test to assess the first impressions. This involved looking at the control (non-AI Max) and treatment (AI Max) campaigns before and after the AI Max adoption date, and comparing the differences between their averages.
The final test statistic suggested a significant increase associated with the treatment group’s IVT levels post-AI Max adoption compared to the control. The IVT seemed to increase in the treatment group.”
Is the increase in IVT definitely due to AI Max?
The team assessed these findings against other possible explanations, such as seasonality and other external trends. But we found that these were unlikely to account for the increase in IVT. The two charts below show average IVT rates for the account’s non-AI Max campaigns across a similar period in 2024 and 2025:
“We compared trends to the same time period last year to gauge seasonal trends, as well as sense checking against trends across the year. After comparing the broad characteristics of both trends (standard deviation and slope), they were considered similar. So it can be safely assumed that the change in IVT wouldn’t be due to seasonal trends.”
Additionally, we checked the account’s 2024 IVT data to identify any trends that occurred in the previous year (prior to using Lunio). But as you can see from the chart below, their IVT rate remained consistent throughout the year, with one spike occurring around October:
On reviewing this data, the team said:
“The 2024 IVT rate data shows that the IVT rate broadly fluctuated around 4.5%, with no discernible trend. This adds to the assumption that any IVT rate change after AI Max adoption won't be due to external trends and can be assumed to be caused by AI Max features.”
So if AI Max is responsible for this rise in invalid traffic, what would the IVT rate have looked like if the brand hadn’t activated AI Max for those campaigns? Our team forecasted the predicted IVT rate without AI Max to provide a clear visual comparison:
“Based on the difference-in-difference test, I wanted to rigorously test the outcome, and forecast the pre-AI Max IVT rates to see what IVT rates could look like if AI Max wasn’t adopted.
The red line on the chart is a simple linear forecast based only on the company’s IVT rates before AI Max adoption. In line with the 2024 trend, the forecast predicts a steady average IVT rate if they hadn’t activated AI Max.
However, the actual IVT rate has increased in this period instead, suggesting that AI Max is driving up IVT rates.”
It’s important to acknowledge that these are early-stage insights from a single account, so they’re not necessarily fully representative. But the data spans almost 900 campaigns, so the results are significant, and can give an indication of AI Max’s broader performance.
What does this mean for marketers?
Increased invalid traffic will inevitably lead to more wasted ad spend, as bots and other fake users click your ads with zero chance of conversion. And the more IVT you have, the more of your budget you could lose. So seeing a rise in IVT due to AI Max activation is a worry, especially for accounts that spend heavily on Google Search.
Invalid traffic has other serious implications for advertisers. As well as draining your ad budget, high levels of IVT can make your data unreliable, and force your sales team to spend time weeding out the fake leads from your CRM. Ultimately it makes your sales and marketing processes much less efficient, and can even impact performance if you’re using Performance Max and other automated campaign types, which rely on clean, accurate data to generate quality conversions.
If you’re already using AI Max (or planning to in future), it’s worth auditing your traffic to see how much IVT your ads are being exposed to. Lunio offers a free 14-day traffic audit to reveal your IVT rate, so you can decide whether it makes commercial sense to deal with it at this stage.
IVT rates of less than 2% aren’t normally too much of a concern. But if you’re seeing IVT rates of 5% or more in your Google Search campaigns (before or after AI Max adoption), there’s usually a strong business case to tackle it. This can reduce financial and time inefficiencies, leaving you in a better position to advertise to genuine users with a real chance of conversion.
Reveal your IVT rate with Lunio
AI Max is designed to help you discover new Search ad opportunities and display highly relevant ads at the right time based on individual intent signals. In short, it’s a new iteration of automated advertising specifically for Search advertisers.
But as more and more case studies are showing, AI Max can prioritize traffic quantity over quality. High reach and impression share can be helpful, but it’s important that you know who is seeing your ads, and whether these users are worth paying for. That’s why it’s essential to track your IVT rate, especially if you’re using AI Max.
Google and other ad platforms are notoriously bad at tackling IVT. And as they make it increasingly difficult to access performance data, advertisers need as much information as possible to ensure they’re getting the best results.
With Lunio, you can see how much IVT is affecting your campaigns. So whether you’re already using AI Max or still weighing up the pros and cons, it’s a great way to gather the data you need to make the best decisions for your business.
