Performance Max's share of ecommerce ad spend peaked in May 2024 and has been slipping ever since.
That is the finding from Smarter Ecommerce's analysis of more than 4,000 Performance Max retail campaigns across 500 advertiser accounts, published by Mike Ryan in April 2025. PMax cost share topped out "just shy of 82%", then lost an average of 0.65 percentage points a month, nearly six points in total.
Six points does not sound like a rout, and it is not one. But it is the first sustained reversal since Google folded Smart Shopping into PMax in 2022, and the spend did not vanish. It went back into Standard Shopping and Search, led by the advertisers with the most data and the most to lose.
This article looks at why that happened, what Google has changed in response, and how to decide which campaign type deserves your budget. The decision depends on three things: catalogue size, margin spread and conversion volume. There is a table for that below, and a test design for settling the question in your own account.
Why the spend started moving back
The turning point was an auction change in October 2024, not a performance collapse. Before that, when the same product sat in both a Performance Max campaign and a Standard Shopping campaign, PMax won the impression automatically. Google removed that priority, so the two now compete on Ad Rank like any other campaigns. Google said it expected "a neutral or positive impact on performance at the account level."
Neutral for Google. For advertisers, it reopened a question that had been closed for two years: does PMax actually beat Shopping, or did it just outrank it?
Early tests reported through Lunio's round-up were mixed. Vervaunt's Josh Duggan saw Standard Shopping wins, with one case where CPCs doubled and another where costs rose 40% alongside a higher auction win rate. Thomas Eccel's early case study found a Standard Shopping campaign was more competitive in the auction after the update.
By late 2025, Sarah Vlietstra at ZATO was putting it more bluntly in Search Engine Land: "Since then, standard shopping campaigns have outperformed Performance Max in many cases." Her explanation is the one most practitioners give. "Performance Max prioritizes easy wins, bidding heavily on branded terms and often inflating campaign-level ROAS."
The Smarter Ecommerce data points the same way. Median PMax ROAS targets rose from about 4.7 to about 6.0 over the study period, and campaigns typically delivered 95% to 116% of target. The system is doing what it was asked. Advertisers tightened the target, and PMax found its cheapest conversions, which are often people who already knew the brand, which is why branded search is the number to watch alongside ROAS.
xychart-beta
title "PMax share of retail Google Ads cost (Smarter Ecommerce, 4,000+ campaigns)"
x-axis ["May 2024 peak", "April 2025 report"]
y-axis "Cost share (%)" 60 --> 90
bar [82, 76]
The chart uses the two figures Smarter Ecommerce published: a peak "just shy of 82%" in May 2024 and a fall of "nearly 6%" by the April 2025 report. Both bars are rounded.
What Optmyzr's 24,702 campaigns add
The second large dataset says PMax does worst when it is competing with your own campaigns. Optmyzr's study of 24,702 Performance Max campaigns found that 82% of advertisers ran PMax alongside Search, Shopping or Display, and that "PMax consistently underperformed when run alongside those other campaigns."
Two other findings matter for budgeting. Accounts that put more than half their budget into PMax (51% of advertisers) posted the strongest ROAS at 652%, but with mixed conversion rate and CPA. And the study saw "potential conversion rate and CPA advantages when keeping PMax limited to 10% to 25% of the budget." In other words, the ROAS looks best when PMax is the whole account, and the unit economics look best when it is a minority.
Both studies agree on the floor. Smarter Ecommerce says PMax campaigns "need at least 30 monthly conversions, and ideally 60 or more". Optmyzr uses the 60-plus benchmark. If a campaign cannot reach 30 conversions a month, automation has nothing to learn from, and that is where a lot of UK SME accounts sit.
What Google changed in 2025 and 2026
Google's answer to the drift has been to give PMax more of Standard Shopping's controls, and then to give Standard Shopping more of PMax's automation. The January 2025 roadmap from Tal Akabas took campaign-level negative keywords out of beta for all advertisers, added brand exclusions by format (so you can block brand terms on text ads but keep Shopping ads), "URL contains" rules for feed campaigns, and age and device controls in beta.
The August 2025 update finished the job on reporting. Search terms reporting became available for every PMax campaign and through the API, the search theme limit doubled from 25 to 50 per asset group, shared negative keyword lists could be applied at campaign level, and full asset-level stats arrived. A channel performance report entered beta at Google Marketing Live.
Then the traffic went the other way. Google added Maximise conversion value bidding to Standard Shopping without a ROAS target, which Search Engine Land noted removes one of the main reasons people ran feed-only PMax. And on 30 April 2026 Google announced AI Max for Shopping campaigns: text customisation from feed attributes, final URL expansion (which can be switched off) and automatic choice between text and Shopping formats, as a one-click upgrade that keeps your product targeting and bidding. Rollout began on 24 July 2026, with Google claiming an average 5% lift in conversions at similar CPA or ROAS.
When Smarter Ecommerce suggested the feature parity might be a prelude to retiring Standard Shopping, Google's Ads Liaison answered directly.
"There are no plans to deprecate Standard Shopping." Ginny Marvin, Google Ads Liaison, in Search Engine Land, April 2025
So the two campaign types are converging from both sides. The remaining differences are about who decides: which placements, which products get the budget, and how much you can see.
What the practitioners are saying now
The experienced end of the market has gone hybrid. Very few are switching PMax off. Austin LeClear's predictions for 2026 at Grow My Ads put "Performance Max adoption declines" at number eight, with the reasoning that "Performance Max tends to plateau, and it often struggles to drive new customers at scale", and that "Hybrid approaches combining PMAX with Standard Shopping and Standard Search are becoming the new best practice."
Tony Adam's May 2026 guide in Search Engine Journal describes the same split in operational terms. Standard Shopping takes the top-revenue SKUs on target ROAS with manual control. PMax takes new-customer acquisition with audience signals, brand exclusions, a negative keywords list for "free" and "cheap" queries, and low-margin SKUs excluded. His threshold for trusting PMax is 30 conversions in the last 30 days.
The r/PPC threads from September and October 2026 are more argumentative, and more useful for seeing where people actually get stuck. In a thread on scaling a 14,000-SKU clothing store on $50 a day per campaign, the poster compared a 2.1 ROAS in PMax with 0.5 in Standard Shopping. Several replies pointed at the sample, not the campaign type. One commenter wrote that "the 2.1 vs 0.5 ROAS gap means almost nothing at 10 and 9 purchases." Another: "Your PMax ROAS is flattered by selection bias. You fed it proven sellers."
A second thread from an account manager who broke a feed-only PMax campaign into segmented Shopping campaigns and saw sales fall drew the same diagnosis: splitting a campaign splits its conversion data, and every new campaign starts learning again. Several commenters also insisted that feed-only PMax "is not dead", and one tested it a few months earlier and found it "still outperformed standard shopping and full PMAX on a bunch of our campaigns."
One detail from that thread is worth remembering. Nearly two years after the auction change, a commenter still advised that "PMax automatically takes priority over Standard Shopping". It does not. A lot of the hybrid structures being recommended online were designed for the old rules.
Decision table by catalogue, margin and data
Pick the campaign type on data volume first, margin spread second, and catalogue size third. The thresholds below come from the Smarter Ecommerce and Optmyzr studies, the Search Engine Journal hybrid model and Google's own experiment guidance. They are starting points, not laws.
| Your situation | Lean towards | Why |
|---|---|---|
| Under 30 conversions a month across Shopping | Standard Shopping, manual CPC or Maximise conversion value | Both large studies put 30 a month as the floor for PMax to learn. Below it, you are paying for automation that cannot see a pattern. |
| 30 to 60 conversions a month, one campaign | One feed-only PMax or one Standard Shopping campaign, not both on the same products | Splitting resets learning. The September 2026 r/PPC case shows the sales dip that follows. |
| 60 or more conversions a month | Hybrid: Standard Shopping for proven SKUs, PMax for acquisition | The Search Engine Journal model. Enough data to run both without starving either. |
| Margins vary widely across the range | Standard Shopping for high-margin lines, PMax excluded from low-margin SKUs | PMax optimises for conversion value, not profit. Margin tiers in custom labels let you set a different ROAS per tier. |
| Narrow catalogue, under 500 SKUs, few bestsellers | Standard Shopping with tROAS | Fewer products means fewer signals for PMax to work with and more value in bidding product by product. |
| Large catalogue, thousands of SKUs, long tail | PMax for the tail, Standard Shopping as a discovery campaign for new lines | Manual bidding on thousands of SKUs spreads budget thinly. Let PMax handle the tail and promote winners. |
| Strong brand search already | Either, but with brand exclusions on PMax and a separate brand Search campaign | Otherwise PMax takes the brand clicks and reports a ROAS you would have had anyway. |
| You need to see search terms and placements for a client report | Standard Shopping, or PMax with the 2025 reporting switched on | PMax now reports search terms and asset stats. It still does not give product-group impression share. |
The first two rows matter most in the UK. Most of the ecommerce accounts we see at Growthcart in Northampton sit under 60 conversions a month, so the choice is usually between the first two rows, and the hybrid model that dominates the US commentary is out of reach until the account grows.
How to test Standard Shopping against PMax properly
Use Google's own experiment tool and give it six weeks. Google Ads has a dedicated Standard Shopping vs Performance Max experiment that compares an existing Shopping campaign against a new or existing PMax campaign on a traffic split. The experiment FAQ sets the ground rules: run it "for at least 4 to 6 weeks", wait "for 1 to 2 conversion cycles", and target the same products in both campaigns. Once the experiment is scheduled, the split cannot be changed.
Here is the design we use when a client asks whether to move back.
- Freeze the account for two weeks before the test. No budget changes, no feed overhauls, no new campaigns. The Reddit cases above are mostly stories of too many changes at once.
- Put the same product set in both arms, and remove those products from every other campaign. Google's FAQ is explicit that products in the test should not also be targeted elsewhere, or the result is contaminated.
- Add brand exclusions to the PMax arm and run a separate brand Search campaign outside the test. Otherwise PMax wins on brand clicks and the test tells you nothing about non-brand performance, which is the brand cannibalisation problem in miniature.
- Split traffic 50/50 and set the same bidding strategy and target in both arms. If one arm has a ROAS target and the other does not, you are testing bidding, not campaign type.
- Run for six weeks minimum, longer if your purchase cycle is more than a week. Judge on conversion value and cost, not on ROAS alone, because ROAS hides volume.
- Report new versus returning customers separately. Google removed the "Unknown" bucket from that report in August 2025, so the split is now usable. If PMax wins on ROAS but loses on new customers, you have learned the thing that matters.
Then do what the data says, and nothing more. If Shopping wins, move those products and leave the PMax arm for acquisition. If PMax wins, keep it, but re-run the test each year, because the auction has changed twice in two years and will change again.
A Manchester agency, Cedarwood Digital, ranks for this query with a 2023 case where a client's revenue rose 184% after moving back to Standard Shopping during a low-intent period. It is a real result, but there is no baseline, no date range and no catalogue size given. That is why the test above matters. Your account needs its own number, not someone else's.
The principle underneath all this is simple. Performance Max is a good system for an account with plenty of conversions, a clean feed and something to say about margin. For an account with fewer than 30 conversions a month, control is worth more than automation, and Standard Shopping is where the control lives. Knowing which to run is one of the things a UK Google Ads agency should settle with a test, not a hunch.
If you want help running the Standard Shopping vs PMax experiment on your own account, our paid media team can set it up and read the results with you. Get in touch.