Performance Max for ecommerce: how to set it up without losing control

Performance Max can scale an ecommerce account quickly, or it can quietly burn budget and cannibalize the brand traffic you were already getting for free. The outcome is decided almost entirely by how you set it up. Here is the structure we use.

Start with the feed, not the campaign

Performance Max for ecommerce is only as good as your Merchant Center feed. Before launching, fix disapprovals, rewrite weak product titles, fill in attributes like brand, GTIN and product type, and add custom labels you can use to segment by margin and performance.

A clean, well-structured feed lifts every downstream metric. Most of the fastest ecommerce wins live here, not in bidding.

Separate your brand traffic

Left alone, Performance Max will happily take credit for branded searches you would have won anyway, making it look more efficient than it is. That is how PMax cannibalizes brand.

Use brand exclusions on your PMax campaigns and run brand search separately, or apply account-level negatives where appropriate. You want PMax earning incremental sales, not reselling you your own customers.

Structure asset groups by theme and margin

Group products that belong together

Do not dump your whole catalogue into one asset group. Split by product category, margin tier or business priority, so you can see what is working and steer budget deliberately.

• One asset group per product theme or margin band
• Strong, distinct creative and copy per group
• Listing groups that isolate your hero products
• Custom labels so you can report by margin, not just revenue

Feed the campaign signals

Performance Max performs better when you give it direction. Add high-quality audience signals, your customer lists, site visitors and in-market segments, and useful search themes so the system starts in roughly the right place rather than guessing.

Signals are a starting point, not a cage. The algorithm will explore beyond them, but good signals shorten the learning period and reduce early waste.

Optimize for new customers and real profit

If you only optimize for total conversion value, PMax will lean toward cheap, repeat purchases from people who already know you. Turn on new-customer acquisition goals and assign a higher value to new customers so the campaign chases growth, not just easy sales.

Where you can, feed profit or margin data back in. Optimizing on profit on ad spend rather than raw revenue is what separates a campaign that looks good from one that actually grows the business.

Accept the reporting limits, then work around them

Performance Max reporting is thinner than search campaigns by design. You will not get full placement or search-term transparency. Use the insights you do get, scripts and listing-group reporting to understand performance, and judge the campaign on outcomes, ROAS, new customers and profit, rather than expecting channel-level detail.