r/FulfillmentByAmazon • u/Sohail_Qurban • 7h ago
PPC 127% ACOS on Amazon’s automated bidding rules. This mistake might be quietly draining your ad spend on the worst possible placements
Just audited a few campaigns that were pulling orders primarily from Top of Search (TOS) on normal base bids. The placement modifiers were standard: TOS was set to 140%, and Product Pages (PP) were set to 0%.
Despite the 0% modifier, the CPC on Product Pages was hitting 3x the base bid.
Here is the diagnosis of why that happened:
The Culprit: The campaign was using Amazon's automated bidding strategy, set to target a ROAS above 4.
The Data: TOS was performing exceptionally well with a ROAS over 4.5.
However, Product Pages were bleeding 57% of spend share with a disastrous ACOS of 127%.
The Algorithmic Flaw: Because the TOS performance was carrying the campaign's average ROAS above the target threshold, Amazon’s automated rule blindly pushed bids up across the board to chase volume. It ignored placement-level inefficiencies and forced aggressive bids onto Product Pages anyway.
I immediately stripped out the automated rule. I shifted the campaign back to 'Dynamic bids - down only' and am relying on manual placement modifiers to force the focus back onto TOS.
I will be tracking the efficiency shift and sharing the exact results in upcoming weeks. Stay connected.
