How to fix Performance Max cannibalizing brand search
Symptom: Performance Max is eating your branded search traffic
Without a brand-exclusion request, Performance Max routinely takes credit for branded search that would have converted anyway. This workflow walks through the 6 fixes iClick applies in the first week on every new account: request PMax brand exclusion, run the reconciliation check against Search, restructure asset groups by margin tier, add negatives, verify data flow, and re-baseline ROAS targets.
- Google Ads editor access (not view-only)
- Merchant Center access (for eCom)
- Recent 90 days of PMax + Search performance data
- Direct email contact with your Google rep (or Premier Partner rep)
- 1
Diagnose whether PMax is actually cannibalising
Pull the last 90 days of Performance Max campaigns from your Google Ads report. Segment by search-term category. If more than 25 percent of PMax attributed conversions map to branded queries (your business name + variants), you have a cannibalisation problem.
Second confirmation: pull the same 90 days for your Brand Search campaign. If Brand Search impression share dropped after PMax launched, that's the smoking gun.
- 2
Request brand exclusions in PMax
The brand-exclusion request is not self-serve, you go through your Google rep or Premier Partner rep. Email them the list of branded terms you want excluded (business name, misspellings, product-brand names).
Expected turnaround: 3-5 business days for the request to process. Ask for confirmation once applied. Do NOT skip this step and assume campaign-level negatives will do the same job, PMax's own docs are explicit that only the exclusion request works.
- 3
Reconcile Search vs PMax attribution
Once exclusions are live, wait 14 days for the algorithm to redistribute. Then pull the same 90-day comparison. You should see Brand Search impression share climb back to pre-PMax baseline within 14-21 days.
If it hasn't recovered by day 21, escalate the exclusion request. Some accounts require a second manual review.
- 4
Restructure PMax asset groups by margin tier
While brand exclusions bake in, restructure your PMax asset groups. Group high-margin SKUs into one asset group with target ROAS calibrated to that margin tier. Do the same for mid-tier and lower-margin catalogs. This prevents PMax from over-serving cheap-and-cheerful products at the expense of your profit drivers.
Rule of thumb: 3-5 asset groups per PMax campaign. More than 5 fragments the signal; fewer than 3 loses margin discipline.
- 5
Add campaign-level negatives from the search-term audit
PMax now has campaign-level negative keywords (as of 2024). Pull the branded terms you excluded above and add them as negatives at the campaign level too. Belt and braces. Also add any competitor brand terms you don't want PMax bidding on.
- 6
Re-baseline ROAS targets and monitor for 30 days
Once cannibalisation is fixed, your reported ROAS on PMax will drop (because it's no longer double-counting branded conversions). This is expected and healthy. Recalculate target ROAS against your margin table and update the tROAS bid target accordingly.
Monitor the account for 30 days. Blended MER is the metric to watch, if it stays stable while PMax's channel-reported ROAS drops, you've fixed the leak without losing revenue.
- Skipping the brand-exclusion request and adding negatives only (does not work in PMax)
- Not waiting 14 days after exclusion for the algorithm to redistribute
- Panicking at the PMax ROAS drop and reversing the exclusion (you'll be back where you started)
- Restructuring asset groups the same day exclusions go live (change one variable at a time)
- Not documenting the pre-fix baseline (you can't prove the fix worked)
Common questions
Want this checked on your own account?
A 47-point written audit of your Google, Meta, or Shopping account. Five business days, no sales call.
