An asset group is the building block of a Performance Max campaign: a themed set of headlines, descriptions, images, videos, and an audience signal that Google assembles into ads across all its inventory. It is PMax's rough equivalent of an ad group.
What lives in an asset group
Each asset group bundles creative assets plus an audience signal around one theme or product line. Performance Max mixes those assets into ads for Search, Display, YouTube, Gmail, Discover, and Maps automatically.
How to structure them
Split asset groups by theme, product category, or margin, so you can feed each a relevant audience signal and read performance in a way that is not fully blended. It is the main structural lever you still control inside PMax, where campaign-level exclusions and reporting are otherwise limited.