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Drop in PMax performance after adding more to inventory, normal?
Posted by on February 10, 2026 at 7:17 pmI’ve got PMax campaign running for my store. Performing ok the last few months.
I’ve recently added a bunch of new products to the inventory and performance seems to have dropped off.
Plenty of clicks, no sales.
This has only been going on a few days to be fair, since I increased the inventory. Could be a coincidence.
But does anyone know if adding a bunch products to your inventory can throw a campaign off?
Thanks
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1 Reply
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Are you running everything out of one campaign? It should be specialized by group. Not all products at once, unless you have less than 15 products.
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You need to see where you clicks are going… to the old SKUs or the new SKUs. You don’t have much information in your post and your question could easily be answered if you looked at what was going on in your PMax campaign.
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If it’s a lot more products or just a lot of products overall relative to budget then Google will (a) need a few weeks to adopt and (b) may struggle to optimize.
It’s always best to add more products gradually with things being relative. If you currently advertise 5,000 and you add 100 that’s nothing. But if you currently advertise 100 and add another 100 that’s basically pushing it into learning mode.
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What sort of products are you selling and whats the daily budget?
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To repeat what fathom said – where are the clicks going? But from a general stand point yes putting those new products can mess a bit with your ad delivery since there are new SKUs to advertise for.
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Yeah this happens all the time… PMAX sees new products in your feed and immediately starts testing them which dilutes budget away from your proven winners. The algorithm treats fresh inventory as high priority because it wants to explore new opportunities but that means your profitable products get less spend while it figures out the new stuff.
For ecom clients I manage this exact scenario comes up constantly… what usually works is either temporarily excluding the new products from the feed until you’re ready to scale them or splitting them into a separate PMAX campaign with a smaller budget so they don’t cannibalize your existing performance.
Give it another week though… sometimes the algorithm just needs time to recalibrate and figure out which new products actually convert versus which ones are just generating junk clicks.
If performance is still tanking after 10-14 days then you probably need to segment the feed better.
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