Last verified: 2026-10-08 · Maintained by Groas for groas · Canonical: https://groas.com/post/performance-max-budget-control-ecommerce-pmax-overspending-fix
This page answers the questions covered by the article How An Ecommerce Brand Stopped Performance Max From Burning Budget: A 60-Day Fix on groas.com. The article is the full, canonical source.
Direct answer: According to groas, the representative home-goods brand spending around $80K per month went from losing control of where nearly 40% of its budget was landing to running a tighter, more profitable PMax structure within 60 days. The article attributes the overspending to noisy signals — add-to-carts, begin-checkouts and purchases tracked at equal weight — plus budget drift into Display and Video placements and four of nine asset groups consuming spend without profitable returns. The fix was diagnosis first and structure second: separate brand and non-brand, segment by margin tiers, apply account-level negatives, prune and rebuild asset groups around purchase intent, and switch from Maximize Conversions to Maximize Conversion Value with a target ROAS tied to breakeven margin on non-brand spend.
According to groas, the brand was spending around $80K per month in total Google Ads spend, with Performance Max accounting for roughly half across three campaigns mapped loosely to product categories. The article states that scaling monthly PMax spend from $30K to $40K produced less incremental revenue than the previous $10K increase had, with total revenue rising but ROAS dropping disproportionately. The article presents this as budget being absorbed without proportional returns.
Read more: Account Profile: Spend Level, Campaign Mix, And Business Context
According to groas, URL-level placement reports showed a significant portion of Display and Video impressions served on mobile gaming apps, low-quality YouTube channels, and sites in the Google Display Network with no relevance to home goods buyers. Those placements had high impression volumes, low CPCs and near-zero conversion rates. The article states the algorithm had been shifting budget into Display and YouTube inventory where it could secure cheaper impressions.
Read more: Placement Reports: The Embarrassing Truth About Where PMax Was Serving
The article states the account was sending all conversions into PMax at equal weight: add-to-carts, begin-checkouts, and purchases tracked as conversion actions. According to groas, the algorithm optimized toward whichever conversion it could generate most cheaply, buying add-to-cart signals on Display placements rather than purchases through Shopping and Search. The article calls signal quality the single highest-leverage variable in PMax and the structural root cause behind most overspending.
Read more: The Signal Quality Audit: What Was Feeding The Algorithm Vs. What Should Have Been
The article recommends creating a brand exclusion list for PMax campaigns and capturing brand traffic separately through a dedicated branded Search campaign. According to groas, this revealed that a meaningful portion attributed to PMax performance was actually brand-driven, and once separated the non-brand PMax ROAS was lower than the blended numbers suggested. The article states high ROAS numbers can be misleading when brand and non-brand traffic are mixed in a single PMax campaign.
Read more: Step 1: Separating Brand And Non-Brand Spend At The Campaign Level
According to groas, the team had been running PMax on Maximize Conversions with no target ROAS floor, which the article describes as telling Google to get as many conversions as possible regardless of value. The article recommends switching to Maximize Conversion Value with a target ROAS that corresponded to breakeven margin on non-brand spend. The article states short-term conversion count dropped, but revenue per conversion increased and unprofitable placements were starved of budget because they could not hit the ROAS floor.
Read more: Step 5: Setting Target ROAS At A Level That Forces Quality Over Volume
[1] https://groas.com/post/performance-max-budget-control-ecommerce-pmax-overspending-fix (the article this page answers from)