PMax Asset Group Optimization: Negative Keywords, Placement Exclusions, & Scripts

Are your Google Performance Max (PMax) campaigns spending tens of thousands of dollars while bleeding ad budget on low-converting mobile app placements, junk YouTube video impressions, and branded search cannibalization? While Google PMax leverages black-box machine learning to serve ads across Search, Shopping, YouTube, Display, Discover, and Gmail, unconstrained AI models often optimize for cheap impression volume rather than true net profit. Learning how to master google performance max negative keywords script optimization configurations allows performance marketers to take back control of ad spend. In this technical guide, you will master segmenting asset groups by margin tier, building account-level negative keyword lists, excluding low-quality mobile app placements, and installing open-source Google Ads audit scripts.

1. Asset Group Architecture: Segmenting by Margin Tier & Intent

A common mistake in PMax campaign setup is bundling your entire product catalog into a single Asset Group. Because PMax prioritizes high-volume SKUs regardless of profit margin, low-margin products consume ad budget while high-margin winners starve.

Structuring Asset Groups by Unit Economics

Structure your PMax campaigns into dedicated Asset Groups based on product contribution margin levels:

• Hero / Best Sellers Asset Group: Top 20% of catalog SKUs generating 80% of historical net profit. Allocate 60% of campaign budget here with aggressive tROAS bid targets.
• High-Margin Accessories Asset Group: Products with 70%+ gross margins. Allows lower tROAS targets to drive high dollar volume profit.
• Clearance / Low Margin Asset Group: Products with <30% gross margin. Require higher tROAS targets (e.g., 450%+) to prevent net financial loss.

2. Implementing Account-Level Negative Keyword Lists & Brand Exclusions

By default, PMax campaigns bid heavily on your own brand name search terms (e.g., “Your Brand Name checkout”), inflating reported campaign ROAS while capturing traffic that would have converted organically.

Step-by-Step Brand Exclusion & Negative Keyword Setup

1. Apply Brand Exclusion Lists: Navigate to PMax Campaign Settings ➔ Additional Settings ➔ Brand Exclusions. Create a Brand List containing your brand name and common misspellings. This prevents PMax from bidding on brand search terms.
2. Account-Level Negative Keywords: Go to Tools & Settings ➔ Shared Library ➔ Account-Level Negative Keywords. Add negative terms like free, login, jobs, customer service, and competitor brand terms to filter search waste across all PMax campaigns.

3. Excluding Wasteful Mobile App & Display Placements

PMax automatically distributes budget across Google Display Network (GDN) and mobile app placements. Mobile casual games (e.g., accidental clicks from children playing mobile games) can waste 15% to 30% of your campaign budget on zero-converting clicks.

Excluding Mobile Apps & Spam Domains

• Go to Tools & Settings ➔ Placement Exclusion Lists.
• Add placement exclusions for adsenseformobileapps.com and select all 140+ mobile app categories under Google Play Store and Apple App Store.
• Exclude low-quality MFA (Made For AdSense) publisher domains using account-level placement exclusion lists.

4. Open-Source PMax Placement Audit & Search Term Google Ads Script

Because Google hides PMax placement placement spend breakdown inside standard reports, install the Google Ads Script below to audit spend distribution across Search, Display, YouTube, and Apps:

function main() {
  var SPREADSHEET_URL = "https://docs.google.com/spreadsheets/d/YOUR_PMAX_SHEET_ID/edit";
  var sheet = SpreadsheetApp.openByUrl(SPREADSHEET_URL).getActiveSheet();
  
  var query = "SELECT campaign.name, asset_group.name, metrics.cost_micros, metrics.conversions, " +
              "metrics.conversions_value FROM asset_group_product_group_view " +
              "WHERE segments.date DURING LAST_30_DAYS";
              
  var searchResults = AdsApp.search(query);
  sheet.appendRow(["Date", "Campaign", "Asset Group", "Cost ($)", "Conversions", "Revenue ($)"]);
  
  while (searchResults.hasNext()) {
    var row = searchResults.next();
    sheet.appendRow([
      new Date(),
      row.campaign.name,
      row.assetGroup.name,
      (row.metrics.costMicros / 1000000).toFixed(2),
      row.metrics.conversions,
      row.metrics.conversionsValue
    ]);
  }
}

5. Auditing Asset Performance Ratings (Best, Good, Low)

Google PMax evaluates individual headlines, descriptions, images, and video assets, assigning performance ratings: Learning, Low, Good, or Best.

• Replace all assets marked Low after accumulating 5,000+ impressions.
• Ensure every Asset Group contains 5 headlines, 5 descriptions, 15 high-res images (Landscape, Square, Portrait), and 5 video assets (Horizontal and Vertical 9:16 Shorts format).
• If you do not upload custom video assets, Google auto-generates low-quality slideshow videos. Upload professional horizontal and vertical video assets to prevent automated video generation.

6. PMax Channel Control Matrix Table

7. Configuring New Customer Acquisition (NCA) Mode

If your primary campaign goal is acquiring new customers rather than re-engaging repeat buyers, enable New Customer Acquisition (NCA) Mode under campaign Customer Acquisition settings:

• Value New Customers Higher: Bids higher for new customers while still permitting repeat customer purchases when ROI is favorable.
• New Customer Only Mode: Restricts campaign ad delivery strictly to new customers using uploaded Customer Match email lists and first-party conversion pixels.

8. Frequently Asked Questions

How do I apply google performance max negative keywords script optimization?

Apply negative keywords to PMax using Account-Level Negative Keyword lists, PMax Brand Exclusion lists, or by requesting Google Support to attach account negative lists directly to specific PMax campaigns.

Can I add negative keywords directly inside a PMax campaign?

Yes. Account-Level Negative Keywords apply automatically to PMax campaigns. For campaign-level negative lists, create a Brand Exclusion list or contact Google Support.

Why does PMax spend budget on mobile games?

PMax algorithms seek cheap impression inventory across the Google Display Network. Mobile app games offer high impression volume, but generate accidental clicks unless excluded.

How do I prevent PMax from auto-generating videos?

Upload at least one horizontal (16:9) and one vertical (9:16) custom video asset into every Asset Group. Uploading custom video assets prevents Google from generating slideshow videos.

What is the recommended number of Asset Groups per PMax campaign?

Maintain 3 to 7 Asset Groups per campaign, grouping assets by product category, target persona, or product margin tier.

How long is the PMax learning phase?

PMax requires 2 to 3 weeks or 50+ conversion events per Asset Group to complete its initial machine learning calibration phase.

Should I run PMax alongside traditional Google Search campaigns?

Yes. Exact Match Search campaigns take priority over PMax for identical search queries, allowing you to maintain strict control over high-intent search terms.

How do I check PMax placement spend details?

Use Google Ads PMax placement audit scripts or view Reports ➔ Standard Reports ➔ Performance Max Placements inside Google Ads Manager.

Can I turn off Google Display Network (GDN) inside PMax?

You cannot toggle off GDN directly, but excluding adsenseformobileapps.com and low-quality placement categories eliminates 90%+ of display placement waste.

What Target ROAS should I set for a new PMax campaign?

Start with a tROAS target based on your actual historical 30-day account performance (e.g., 250%), then increase targets gradually in 10–15% increments as performance stabilizes.

Advanced Feed-Only PMax Setup for High-Intent E-Commerce

For e-commerce brands wanting to restrict PMax strictly to Google Shopping auctions without spending on Display or YouTube, build a Feed-Only PMax Campaign by creating an Asset Group that contains zero text headlines, descriptions, or images, relying solely on your Google Merchant Center product feed.

Script-Based Automated PMax Search Term Harvesting

Use Google Ads Scripts to extract search terms triggered by PMax search themes into a Google Sheet, automatically identifying high-converting search queries to migrate into dedicated Exact Match Search campaigns.

Auditing PMax Channel Budget Distribution via BigQuery & API Exports

Because Google Ads native reporting obfuscates dollar spend allocation between Search, Display, YouTube, and Gmail inside PMax campaigns, enterprise advertisers query raw Google Ads API tables or BigQuery data transfers to unpack channel spend distribution:

SELECT
  campaign.id,
  campaign.name,
  segments.ad_network_type,
  SUM(metrics.cost_micros) / 1000000 AS cost_usd,
  SUM(metrics.conversions) AS total_conversions,
  SUM(metrics.conversions_value) AS conversion_value_usd
FROM `your_project.google_ads.sample_table`
WHERE segments.date DURING LAST_30_DAYS
GROUP BY 1, 2, 3
ORDER BY cost_usd DESC;

Uncovering channel distribution via SQL reveals whether your PMax campaign is functioning primarily as a high-converting Shopping engine or draining funds on Display Network placements.

Audience Signals vs. Strict Audience Targeting

A critical technical distinction in PMax is understanding Audience Signals. Adding custom segment lists (e.g., website visitors, customer email lists, or high-intent search terms) to a PMax Asset Group acts as an initial machine learning steering signal, NOT a hard targeting boundary.

• Initial Prospecting Phase: PMax uses your Audience Signals to identify early high-probability converting users.
• Expansion Phase: As conversion volume increases, PMax machine learning algorithms expand targeting beyond your specified signals to find similar converting users across Google’s entire ad network.

Troubleshooting Low Asset Group Impression Volume

If a newly created PMax Asset Group fails to spend budget or generate impressions, execute the following 4-step diagnostic checklist:

• Verify Product Feed Disapprovals: Check Google Merchant Center for disapproved SKUs, missing GTINs, or policy flags restricting item eligibility.
• Audit Overly Aggressive tROAS Targets: Setting a Target ROAS goal significantly higher than your historical 30-day average (e.g., setting a 500% target when historical ROAS is 220%) causes PMax AI algorithms to choke ad impression delivery.
• Review Brand Exclusion Lists: Ensure your Brand Exclusion list does not accidentally contain broad non-brand product category terms.
• Check Asset Requirements: Confirm that all mandatory image aspect ratios (1.91:1, 1:1, 4:5) and text fields are populated.

How does Final URL Expansion impact PMax traffic quality?

When Final URL Expansion is enabled, Google’s AI routes search traffic to alternative landing pages on your domain based on user search intent. Disable Final URL Expansion if you want traffic routed strictly to your designated high-converting landing page.

What is the recommended video length for PMax YouTube assets?

Provide 15-second and 30-second landscape videos for standard YouTube in-stream placements, and 10 to 60-second vertical 9:16 videos for YouTube Shorts.

Automating PMax Campaign Budget Reallocation via Open-Source Python Scripts

For large-scale Google Ads accounts managing multiple regional PMax campaigns, automate daily budget reallocation using Python scripts interacting with the Google Ads API. Automatically shift budget away from under-performing campaigns toward high-ROAS Asset Groups:

from google.ads.googleads.client import GoogleAdsClient

def adjust_pmax_budget(client, customer_id, budget_id, new_amount_micros):
    campaign_budget_service = client.get_service("CampaignBudgetService")
    campaign_budget_operation = client.get_type("CampaignBudgetOperation")
    
    budget = campaign_budget_operation.update
    budget.resource_name = campaign_budget_service.campaign_budget_path(customer_id, budget_id)
    budget.amount_micros = new_amount_micros
    client.copy_from(campaign_budget_operation.update_mask, protobuf_helpers.field_mask(None, budget._pb))
    
    response = campaign_budget_service.mutate_campaign_budgets(
        customer_id=customer_id, operations=[campaign_budget_operation]
    )
    print(f"Updated Budget Resource: {response.results[0].resource_name}")

Optimizing Custom Intent Audiences using Competitor URLs & Search Terms

To steer PMax machine learning algorithms toward high-intent buyers, build advanced Custom Intent Audience Signals inside Google Ads Audience Manager:

• People who searched for any of these terms on Google: Enter top 20 high-intent transactional search queries (e.g., buy enterprise crm software or best b2b sales automation platform).
• People who browse types of websites: Input direct competitor domain URLs (e.g., competitor.com/pricing). This signals PMax algorithms to target users actively researching competing options.
• People who use specific apps: Add relevant competitor or industry mobile apps to refine initial machine learning prospecting.

Combining Custom Intent Signals with strict account-level negative lists maximizes PMax conversion efficiency across all ad networks.

Conclusion

Executing systematic google performance max negative keywords script optimization strategies converts PMax from an unpredictable black box into a profitable scaling engine. Eliminating placement waste and protecting brand search terms ensures your paid media budget drives real business growth.

Need expert assistance optimizing your Google PMax campaigns or building custom audit scripts? Schedule a PMax optimization audit with our performance engineering team today.