Is Performance Max Cannibalizing Your Search and Brand Campaigns?
You launched Performance Max and the results look great: strong ROAS, plenty of conversions. Then you look at your Search campaigns. Clicks are down, and your brand campaign has dropped in ad spend and conversions.
That's cannibalization with PMax taking credit for searches your Search and brand campaigns were already capturing, and you're often paying more for them.
This is one of the first things I check when I audit an account that runs PMax next to Search. Here's how Google decides which campaign serves, the three reports I use to spot overlap, and what I'd change.
Does Performance Max Include Search?
Yes. PMax can show ads on Google Search, along with Shopping, YouTube, Display, Gmail, Discover and Maps. When you run PMax and Search in the same account, both can be eligible for the same query.
Google uses two rules to decide which one serves (Google Ads Help):
If a Search campaign has a keyword identical to the search (or a spell-corrected version of it), Search gets priority over PMax.
If no keyword is identical to the search, the campaign with the higher Ad Rank serves.
The second rule is where the problem starts. Most searches don't match a keyword word for word. Think close variants, longer queries, and brand searches with an extra word like "[brand] reviews" or "[brand] coupon." For all of those, PMax competes on Ad Rank, and PMax bids aggressively on searches that convert easily, which usually includes brand.
Signs PMax Is Taking Your Search and Brand Traffic
One of these on its own could be seasonality. Two or three together usually mean PMax is overlapping with Search.
Brand campaign impressions drop right after PMax launches, while branded search volume in Search Console or Google Trends stays flat.
Search campaigns lose impression share on their best keywords, with no change to budget, bids or competitors.
PMax ROAS is higher than your brand campaign's ROAS. That usually means PMax is serving on brand searches.
PMax conversions go up, but total account conversions don't.
Blended CPA rises, because you're paying PMax prices for clicks Search used to get for less.
Performance Max Cannibalization Case Study
A recent Performance Max audit uncovered a brand cannibalization issue the client wasn't aware of. The client had intentionally chosen not to run separate brand campaigns and had added brand negatives to their PMax campaigns to keep branded searches out.
The problem was that the negative keyword lists weren't comprehensive enough. PMax was still capturing brand variations and misspellings, which made the campaign's non-brand CPA look better than it actually was. At the same time, PMax was applying bids designed to acquire non-brand traffic to relatively inexpensive, high-intent brand searches.
We recommended taking a different approach: create small-budget brand Search campaigns and build more comprehensive brand negative keyword lists for PMax. This allowed us to separate brand and non-brand traffic, control the bids independently, and get a much clearer picture of what the client was actually paying for brand traffic.
The Results
Once branded searches were separated from PMax, the difference was significant:
Brand Traffic in PMax | Brand Search Campaigns | Change | |
Average CPC | $0.98 | $0.38 | −61% |
CPA | $10.32 | $3.54 | −66% |
The brand traffic was substantially more efficient when it was managed separately. Average CPC fell from $0.98 to $0.38, while CPA dropped from $10.32 to $3.54.
More importantly, separating the campaigns gave us a much more accurate view of non-brand performance. Without isolating brand traffic, the PMax campaign's overall CPA made the non-brand portion of the campaign appear more efficient than it really was.
How to Check for Cannibalization
Check these three reports.
PMax search terms report. Open the PMax campaign and go to Insights and reports > Search terms. Sort by conversions. If your brand name or the queries your Search campaigns target are in this list, PMax is overlapping with them.
Channel performance report. This shows how PMax spend and conversions split across Search, Shopping, YouTube, Display and the other channels. If most PMax conversions come from Search, PMax is doing the job your Search campaigns should be doing.
Search impression share, before and after. Compare Search impression share and Search lost IS (rank) on your top keywords for the 30 days before and after PMax went live. If lost IS (rank) jumped and you didn't change bids, PMax is likely winning those auctions.
Then compare total account conversions for the same two periods. If PMax reports 40 new conversions and the account only grew by 5, the other 35 came from campaigns you already had.
How to Stop PMax From Cannibalizing Search
Start with brand. That's where most of the money goes.
Add a brand exclusion to PMax. Create a brand list with your brand name and apply it in the PMax campaign settings''
Add campaign-level negative keywords. PMax allows up to 10,000 negative keywords per campaign. Use them for brand variations the exclusion misses, competitor names you run in their own campaign, and irrelevant queries from the search terms report.
Add your best queries as keywords in Search. A keyword identical to the query gives Search priority. This is the most reliable way to keep your top searches in the campaign where you control the ad copy and landing page.
Decide what PMax is for. For e-commerce, that's usually Shopping and product sales. Google stopped giving PMax automatic priority over Standard Shopping in Q4 2024, so I recommend running Standard Shopping alongside it (more in my post on Feed Only vs. Standard Shopping). For lead gen, if Search already covers your demand, ask whether you need PMax at all. Tightly themed asset groups help too: see Performance Max asset group themes.
Check again after 30 days. Run the same three reports. Brand CPC should drop, Search impression share should recover, and total conversions should hold steady or go up.
When Some Overlap Is Fine
Some overlap is expected. If PMax is picking up long-tail searches you never had keywords for, and total conversions are growing, PMax is doing its job. A small account with one Search campaign and a tight budget can also get reach from PMax that Search wouldn't find.
The test I use: after PMax launched, did the account get more conversions at a CPA you're happy with? If yes, the overlap is worth it. If total conversions stayed flat, you're paying twice for the same customers.
If you're still deciding whether to run PMax at all, read my comparison of Performance Max vs. Search campaigns. For e-commerce accounts, see Standard Shopping vs. Performance Max.
FAQ
Does Performance Max include Search?
Yes. PMax can serve on Google Search, so it can compete with your Search campaigns for the same queries.
Will PMax bid on my brand name?
It can, and often does, unless you add a brand exclusion or brand negative keywords to the PMax campaign.
Which wins when PMax and Search are both eligible?
Search wins if it has a keyword identical to the query. Otherwise, the campaign with the higher Ad Rank serves.
Should I pause PMax if it's cannibalizing Search?
Usually not. Add a brand exclusion, add negatives, and cover your top queries in Search first. Pause PMax only if total conversions don't improve after those fixes.
Final Thoughts
PMax can bring in new customers, as long as you keep it out of searches your other campaigns already win. Add a brand exclusion, clean up negatives, and keep your best queries in Search. Then judge PMax by what happens to total account conversions.
If your PMax results look too good, or your Search campaigns went quiet after launch, I can take a look. I offer Performance Max management along with other account fixes and ongoing optimization.
