Case studyEcommerceNovember → December
Shopping coverage 49% → 57% in one month
Feed duplication expanded impression share without forcing spend
- November IS
- 49.04%
- December IS
- 57.06%
- Net gain
- +8 pp
Feed duplication, done properly
Shopping performance doesn't usually jump because of bidding. It jumps when coverage improves. Over the last month, overall Shopping impression share increased from 49% to 57%. Not by pushing budgets. By fixing how products were surfaced.
We didn't increase bids or loosen targets. We implemented a feed duplication strategy with strict role separation between Shopping and Performance Max.
How feed duplication actually works
01
Duplicated the product feed intentionally
Not as a hack. As a structural decision to give Shopping and PMax distinct feeds with distinct rules.
02
Segmented product sets by role and query behaviour
Each feed serves a specific campaign type with a specific query intent. No catch-all.
03
Allowed Shopping and PMax to surface products more frequently
More eligible auctions across the catalogue without sacrificing efficiency. Coverage compounds because the underlying eligibility is broader.
Auction Insights, month over month
| Period | Impression share |
|---|---|
| November (Nov 1 – 30) | 49.04% |
| December (Dec 1 – 24) | 57.06% |
| Net gain | +8 percentage points |
Same competitors. Same budgets. Different feed architecture.
Where these numbers come from
Patrick first wrote this account up on the newsletter on 28 January 2026, the week the numbers landed. The figures on this page come from that write-up.
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