Cutting ACoS without losing the Buy Box
When a seller asks us to bring ACoS down, the instinct is to cut bids across the board. It works for about two weeks, and then organic rank starts sliding and the Buy Box gets contested. The order you do things in matters more than the size of the cut.
Do the structural work first
- Separate match types. Exact, phrase and broad in their own campaigns. You cannot manage what is averaged together.
- Harvest search terms weekly. Convert the performers into exact match, and add the rest as negatives.
- Negative aggressively. Most wasted spend on a mature account sits in a small number of irrelevant terms nobody has looked at in months.
Cutting bids on converting keywords to hit an ACoS target is how sellers accidentally buy themselves a ranking problem.
Then protect the Buy Box
Buy Box share depends on price, stock, fulfilment and seller metrics — not on ad spend. But losing it wrecks your ad performance, because the traffic you are paying for lands on a page where the buy button belongs to somebody else.
Only then adjust bids
With structure clean and Buy Box stable, bid work becomes precise: reduce where ACoS is above target and conversion is weak, hold where the keyword is defending rank. That is a decision per keyword, not a percentage applied to everything.
