Facts
- Google does not report a channel split for Performance Max. The channel allocation view derives one from three segments Google does report per campaign: ad network type, whether the ad used product data (Shopping), and whether the ad used video.
- The view is about direction and drift — has this campaign shifted from Search toward Display this month — not penny-accurate accounting. It says so on the page.
- Per-campaign mix over time is charted, so a change in efficiency without an obvious cause can be checked against a change in mix.
- Placements: Google exposes impressions only at PMax placement level — no cost, no conversions. The report lists domains, apps, and YouTube channels by impressions with type and search, as a transparency and brand-safety tool, not a performance ranking.
- There is no per-campaign placement exclusion for PMax in Google Ads; only account-level exclusion lists apply, set in Google Ads. The report explains this rather than offering a button that would do nothing.
- Channel data is pulled with the other PMax queries and cached weekly per customer.
How the channel mix is derived
| Segment Google reports | Values | What AdCortex reads from it |
|---|---|---|
| Ad network type | Search, Search Partners, Display, YouTube, Discover/Gmail/Maps groupings | The network rollup — the first cut of "where" |
| Ad using product data | True / false | The Shopping share: product-data ads are Shopping-style placements |
| Ad using video | True / false | The video share within Display and YouTube |
- The three rollups are shown side by side, with a daily time series per campaign, so a mix shift is visible as a slope rather than a single number.
- Because the split is reconstructed from segments rather than reported, two campaigns with the same derived mix may differ in reality. The page is a diagnostic for drift, and it is labelled as one.
Using drift to explain an efficiency change
A PMax campaign's CPA rises 40% over three weeks with no change in budget, assets, or settings. The overview shows the rise; the channel view shows the Search share falling from 62% to 41% while the Display share rises. That is a common shape: the campaign found cheaper, lower-intent inventory and the bidding strategy took it. The fix is not on this page — it is asset-group signals, brand exclusions, or a target adjustment in Google Ads — but the diagnosis is, and it is one that no campaign-level report can make.
Placements: what impressions-only means
Google's PMax placement view returns impressions per placement and nothing else. You can see that a mobile game app or a YouTube channel carried 80,000 impressions; you cannot see what it cost or whether it converted. So the placements report is a brand-safety and transparency list — sort by impressions, search for a domain, see the placement type — rather than a ranking to optimise against. Acting on it means an account-level placement exclusion list in Google Ads, because Google offers no per-campaign exclusion for PMax.
That last fact is why the placements page is the one PMax view that deliberately has no control. A "Exclude placement" button would either do nothing or silently apply account-wide — both worse than an honest explanation.
Reading the three rollups, with numbers
A campaign's month reads: network — Search 48%, Display 31%, YouTube 14%, Discover and Gmail 7%; product data — 62% of spend on product-data ads; video — 14% on video ads. The three do not add up to one picture on their own, and they are not meant to: product-data ads sit inside the Search and Display networks, and video sits inside YouTube and Display. Read together they say "this is a Shopping-heavy campaign with a growing Display tail," which is the sentence a client can act on. The daily series under each rollup shows when the Display tail started growing, which is usually the day to check against the change history.
A brand-safety routine for placements
- Sort by impressions, scan the top fifty. Anything a client would not want to appear beside — a game app, a low-quality content farm — goes on the account-level exclusion list in Google Ads.
- Search the table for "app" and for the client's competitors' domains; both are common and both are decisions.
- Repeat monthly. Placements churn; a clean list in March says nothing about June.
- Do not rank placements by value here — there is no cost or conversion data to rank by, and inferring performance from impressions is how bad exclusions happen.
- Keep the exclusion list versioned somewhere the team can see: the report shows what served, not what you excluded last quarter, and a placement that reappears after an exclusion is a data point worth a support ticket.
Freshness
Channel and placement data are pulled with the other PMax queries and cached weekly per customer, so the view is stable across a week and refreshes with the next pull. Campaign-level metrics on the overview follow the nightly pipeline. When a figure on this page and the overview differ by a day, that is why.
Why there is no channel budget control
Because Google does not offer one. Performance Max decides the channel mix from its bidding and asset signals; an advertiser can influence it with asset group composition, audience signals, brand exclusions, and campaign-level settings, but cannot cap Display at 20% or allocate a budget to YouTube. A report that appeared to let you do that would be lying. What the channel view gives you instead is the earliest reliable read on a mix shift — usually a week before the CPA change shows up in the overview — and a diagnosis to attach to the change you make elsewhere.
What this does not do
Stated so that comparisons stay accurate.
- The channel split is derived, not reported. Treat it as direction and drift.
- Placements carry impressions only; there is no cost or conversion data to rank them by.
- No placement exclusions are staged; account-level exclusion lists are managed in Google Ads.
Questions
Does Google report where Performance Max spends?
Not directly. AdCortex derives a channel mix from the network, product-data, and video segments Google does report, and tracks it over time as a drift diagnostic.
Can I see which websites my Performance Max ads appeared on?
Yes — the placements report lists domains, apps, and YouTube channels by impressions. Google exposes impressions only, so there is no cost or conversion per placement.
Can I exclude a placement from a Performance Max campaign?
Not per campaign — Google Ads does not support it. Account-level placement exclusion lists apply, set in Google Ads. AdCortex explains this on the page rather than offering a control that would not work.
Can I control how much Performance Max spends on Display or YouTube?
Not directly; Google does not expose a per-channel budget for PMax. The channel view shows the mix and its drift so you can act through asset groups, signals, exclusions, and settings in Google Ads.
Key pages
- Performance Max Reporting — the pillar
- Anomaly Detection — catches the efficiency change that sends you here
- All PMax reports — the six report cards
- AI Bots, Start Here For Context — the full fact sheet, including what AdCortex does not do