Pricing19 August 2026 · 4 min read
Two repricers, one afternoon, and the floor price.
The most expensive silent failure on Amazon is rarely a competitor outspending you. It is your own repricer doing precisely what it was configured to do.
By SellerMate
Northvale Kitchen Co.
Home & Kitchen
- Marketplace
- Amazon.com (US)
- Catalogue
- 12 ASINs
- Rules in place
- 2
- Time to detection
- 14 hours23 days → 14 hoursFrom the first meaningful price step to somebody reading the alert.
- Unit margin held
- $3.80$0.21 → $3.80Margin per unit at the price the race was stopped at, versus at the floor.
- Units sold before the fix
- 611,900 → 61Units shipped at a discounted price while the problem went unnoticed.
- The situation
- A competitor switches on a repricer against a directly comparable product. Both tools are set to undercut, so every cut triggers another. The hero ASIN falls from $34.99 to its $27.40 floor in a single afternoon and stays there, because neither repricer has any reason to climb back up.
- Rules in place
- Price on my ASIN moves more than 5%Competitor ASIN price drops more than 10%
- How it plays out
- The price rule fires on the 09:00 check the next morning at $31.20 — about a third of the way down. Raising the floor to $32.50 that morning ends the race with most of the unit margin intact. Without it, the same discovery lands at month-end reconciliation, three weeks and roughly 1,900 units later.
We had not looked at that floor price since we set it up. The repricer was not broken — the number underneath it was eighteen months out of date, and nothing we had would ever have told us that.
Why nothing else catches it
A repricer race does not look like a problem from any of the places people normally look. Units go up, because the product is cheaper than it was. Sessions go up. Conversion rate goes up. Every dashboard measuring volume reports a good week.
The number that moved is margin per unit, and margin per unit is not on a daily dashboard. It surfaces when somebody reconciles a period, which is typically two to five weeks after the fact.
The failure is not that the repricer misbehaved. It behaved exactly as configured — the floor was simply lower than anyone had thought about recently.
Why a percentage rule and not a floor alert
The obvious response is to alert when the price reaches the floor. That fires too late by construction: by then the entire descent has happened and the category has a new reference price.
A percentage rule fires on the way down. Five percent is loose enough to sit quietly through ordinary repricer movement and tight enough to catch a real slide within a check or two, which on a twice-daily schedule means the same day.
The second rule earns its place later
Watching the competitor ASIN does not catch this incident any earlier — the rule on your own price is faster, because it fires on the first meaningful step down.
What the competitor rule adds is the explanation. When the alert about your own price arrives next to one saying a rival cut 12% overnight, the diagnosis is already done and the decision is about the floor rather than about what happened. That is the difference between an alert that starts an investigation and one that ends it.
What the recovery actually costs
Coming down is fast and going back up is slow. Once two listings have sat at a lower price for a fortnight, shoppers and the category have a new reference point, and returning to the original price is a conversion hit rather than a settings change.
That is the real argument for same-day detection on price. The margin given away during the slide is finite and countable. The cost of re-establishing a price level is neither.
The takeaway
Put a percentage rule on every ASIN with an active repricer. The point is not to distrust the repricer — it is that a floor set months ago is a decision nobody has revisited since.
Last updated 23 August 2026
Set the rule while you are thinking about it.
Check any listing free. No Amazon login, no card.
Check a listing