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Sudden CPC spike on Performance Max
Posted by on December 3, 2025 at 1:10 pmHey everyone,
I’m seeing a strange behavior on one of our Performance Max campaigns. The average CPC jumped from €0.10 to €0.30 in just one week — a 3x increase.
Interestingly, the campaign has been delivering almost entirely on the Search network (~99%), so I'm wondering if it could make sense to make a search campaign and set a maximum cpc.
I already checked the keywords, and yes, there was one that drove up the cost a lot — but even after removing it, nothing changed.
Has anyone seen this kind of sudden CPC spike on PMax? How would you go about investigating why the cost per click shot up so quickly? Any tips for checking what’s causing the shift in placement or auction dynamics would be super helpful.
Thanks in advance for any insights!
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1 Reply
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Yes happened with me just yesterday. Pmax campaign spent 6x daily budget just 2 hours after launching. Greedy bastards 🤣
It felt like “conversion opportunity” . I take it as “budget opportunity” 😜. Someone told me to use end dates on campaigns and keep pushing it . No big deal. Will try this . -
This could be for many reasons.
1. We’re just coming off of Thanksgiving… if you’re not in consumer goods some competitors might have paused campaigns and just turned them back on.
2. Your P-Max campaign is finding it’s footing with respect to conversions and bidding up on queries that are more likely to convert… this will often happen if it’s outperforming your tROAS or tCPA
3. Unrelated changes in supply and demand, or changes you’ve made to the campaign influencing bidding/spending
4. I would normally suggest a change in inventory, but if that hasn’t migrated from display/video as you’ve suggested it hasn’t this won’t apply.
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Last week was Black Friday and then past Monday was Cyber Monday,… so Google can get crazy and doesn’t know what to do this week. That can have things spike because Google still thinks we should be bidding aggressively when things slow down on Tuesday.
If you are not a consumer brand doing Black Friday, then you need to audit the PMax campaign and see what else has changed in the campaign beyond the CPCs.
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