The choices that other advertisers, who are participating in the same auctions as you, make can affect your campaign’s performance. New advertisers or advertisers who adjust their existing accounts can affect how many impressions your ads receive.
Example
If another advertiser, who is using the same targeting as you, decides to lower their tCPA on one of their campaigns, your ads may win in fewer auctions and be shown to potential converting customers less frequently.
Note: Merchants in CSS countries using more than one CSS may experience performance fluctuation between accounts for Performance Max and Shopping campaigns. This is because although multiple accounts are bidding, only one can win each auction.
For example, the performance of your campaign with CSS A could drop, while the performance of another of your campaign with CSS B targeting the same products could increase.
A merchant will never be second-priced against itself in the auction for any offer, and that rule holds irrespective of the number, or identity, of the CSSs used by the merchant. Learn more about auction dynamics between CSS.
What you can do
If you believe auction dynamics may be causing low serving or performance fluctuations, you can choose to raise your tCPA or lower your tROAS to try to increase serving. You can also lower your budget to ensure your campaign doesn’t spend too much at a level you’re not comfortable with.
Need something else?
Check other common reasons why your campaign performance is fluctuating.
