In 2026, the most effective way to “group” PMax budgets is by linking them to a Portfolio Bid Strategy. This allows multiple campaigns to work toward a single ROAS or CPA goal while sharing a collective “brain.”
Go to Tools: Click the Tools icon (spanner/wrench.
Open Budgets and Bidding: Select Tools > Budgets And Bidding > Bid strategies.
Create Portfolio Strategy: Click the button and choose your strategy (e.g., Target ROAS).
Include Campaigns: Select all the PMax campaigns you want to group together.
Set Shared Constraints: Here is the “limit” part: You can set a Maximum Bid Limit and a Shared Budget (if your account version allows PMax in shared budgets).
In 2026, Google started allowing some PMax campaigns to use Shared Budgets only when paired with a Portfolio Bid Strategy.
Technical Budget Rules
The “Shared Budget” Trap
Historically, PMax campaigns were incompatible with Shared Budgets because they need stable, dedicated funding to feed the AI. If you force PMax into a shared budget with a standard Search campaign, the PMax campaign will often “eat” the entire budget before the Search campaign even gets a chance to show an ad.
Recommendation: Only share budgets between PMax campaigns that have the same product margins and goals.
Salesforce
