What is Dynamic Bids Up and Down?

Dynamic bids, up and down is the Sponsored Products bidding strategy in which Amazon may increase your bid in real time when it predicts a click is more likely to convert, and reduce it when it predicts the opposite. The increase is capped by a limit Amazon publishes, and the cap is not uniform: top of search is allowed a larger uplift than the other placements. Check the current figures in the campaign manager rather than relying on remembered ones, since Amazon has changed them before.

The compounding to watch

The uplift applies on top of your placement modifier, not instead of it. A bid raised by a top of search modifier is the figure Amazon then raises again. Sellers who set an aggressive modifier and then switch to up and down are frequently surprised by the resulting cost per click, and the surprise is arithmetic rather than misbehaviour.

The whale paradox

This strategy breaks a habit most people have. Under fixed or down only bidding, your realised cost per click cannot exceed your bid, placement modifiers aside. Under up and down it can. That has a specific consequence for anyone automating bids: any rule that reasons from the stored bid rather than from realised cost per click can compute a raise for a keyword that is already spending well over target. The bid looks low. The actual spend is not.

Shurq's optimiser anchors its reductions on the lower of the stored bid and the realised cost per click, precisely so that an over target keyword cannot be raised by that arithmetic.

ACOS = CPC ÷ RPC

Because ACOS has only two inputs, and up and down moves one of them without your involvement, the strategy is best treated as something that alters your cost side rather than as an optimisation of it.

When it earns its place

Use it where the conversion data behind the keyword is strong, the margin has headroom above break even, and you would genuinely want to pay more for a better than average auction. Exact match campaigns on proven terms are the natural home.

Avoid it while you are still discovering search terms. Up and down on an auto or broad campaign gives Amazon licence to bid harder on queries you have not yet decided you want.

Before switching

Record the current cost per click, switch one campaign at a time, and give the change a settled window before judging it. Attribution reports late, so an early reading of a bidding change usually flatters or damns it unfairly. If you also change a placement modifier in the same week you will not be able to say which move did what.