If your product is still live on Amazon, in stock and well reviewed, and sales fall 80% overnight, it is nearly always the same thing: you have lost the Buy Box. No warning, no email, no notification. The button simply stops being yours and the chart falls off a cliff.
What the Buy Box is and why you barely sell without it
The Buy Box is the panel on the right of a product page holding the "Add to Basket" and "Buy Now" buttons. A single Amazon listing can have several sellers offering exactly the same product, but only one occupies that panel at any given moment. The rest get pushed into "Other Sellers on Amazon", a link almost nobody clicks.
The split is brutal. The figure used across the industry is that the Buy Box concentrates somewhere around 80-90% of a listing's sales, and on mobile the imbalance is worse because the other offers are not even visible without scrolling. Translated: losing the Buy Box is not losing margin, it is ceasing to sell.
There is a second effect people underestimate. Without the Buy Box you cannot run Sponsored Products on that ASIN. Campaigns stop serving, so you lose organic and paid sales at once. And because those campaigns stop generating clicks and conversions, organic ranking starts to slide too. A 30p pricing problem turns into a ranking problem within three weeks.
Once an ASIN loses the Buy Box, the clock is running. The longer it takes you to spot it, the more expensive the way back.
What Amazon weighs up
Amazon does not publish the algorithm, but it does document the general criteria and in practice they behave fairly predictably. These are the ones that move the needle:
- Total price to the customer, not the product price. Item plus delivery. A competitor £1 dearer with free delivery can still beat you.
- Stock availability. No stock, no Buy Box, and coming back into stock does not hand it straight back.
- Fulfilment method. Offers fulfilled by Amazon (FBA) or Seller Fulfilled Prime start ahead of standard merchant fulfilment, because they carry an implied delivery promise and a defect rate Amazon already knows.
- Delivery speed and reliability. The promised date counts, and so does your record of hitting it.
- Account metrics. Order defect rate, late dispatch, pre-fulfilment cancellations, message response time, valid tracking.
- Seller history. An account with years of good behaviour and volume outweighs a new one with identical metrics.
One important nuance: the Buy Box can rotate. When two offers are closely matched, Amazon shares the time between them. That is why sellers report "sometimes I have it, sometimes I don't" and assume the dashboard is broken. It is not.
It is also possible for nobody to hold it. If Amazon judges every offer to sit above a reasonable reference price, it suppresses the panel and shows "See All Buying Options" instead. That case is almost always about price.
Quick diagnosis: symptom, likely cause, what to do
| Symptom | Likely cause | What to do |
|---|---|---|
| Sales collapse on one ASIN, rest of the catalogue is fine | Another seller has undercut you on that listing | Compare total price including delivery. Adjust, and find out who the seller is |
| Several ASINs drop at once, all exclusively yours | Account health or fulfilment problem | Check account health dashboard and dispatch metrics |
| Listing shows "See All Buying Options" and nobody has the button | Price above Amazon's reference point | Bring it into range, or review the ASIN's price history |
| You have it some of the time and lose it the rest | Buy Box rotating between closely matched offers | Differentiate on something other than price: delivery window, fulfilment |
| You lose it right after switching warehouse or carrier | Longer promised delivery date | Correct the real lead time and watch late dispatches |
| You lose it on your own bundle or multipack, no competition in sight | Amazon comparing your bundle to the equivalent unit price | Check the per-unit price of the bundle against the single item |
| Stock hits zero for a few hours and does not return afterwards | Availability history reset | Hold stock steady for a few days; it usually restores itself |
| An unknown seller is cheaper than your own cost price | Diverted stock, grey market or a fraudulent account | Document it and raise a claim; do not start a price war |
The unauthorised seller who wrecks your price
This is the one that stings. You sell your own brand, your price is calculated with its margin, and one day a seller you have never heard of turns up on your listing 15% below you. They take the Buy Box, your campaigns stop serving, and you are left watching.
First job is working out where the stock came from. Usually it is one of these: a distributor of yours reselling outside the agreed channel, clearance stock bought from a third party, repurchased returns, or outright counterfeit.
What works, in order:
- Buy a unit yourself. It gives you the seller name, the delivery note, the batch number and sometimes the origin. Without proof of purchase you can barely claim anything.
- Audit your distribution network. The batch number usually tells you which customer received that pallet. If it is channel leakage, the fix is contractual, not an Amazon case.
- If your trade mark is registered, use Brand Registry. That is the route for counterfeit or misuse of your intellectual property. Procedures and timescales change, so check the current ones in Seller Central.
- Do not cut your price by reflex. Enter the spiral and you are the one who loses: the other seller has a different acquisition cost and probably limited stock. Cutting also sets a lower price history that will constrain your future Buy Box.
The real preventive measure is not on Amazon at all, it is in your distribution contract and your pricing policy. No channel clause, and this will happen again.
Bundles and multipacks that lose the Buy Box
This one baffles people because there is no competition: you are the only seller on the ASIN and still there is no button.
The usual explanation is that Amazon compares your bundle with the per-unit price of the single item, both on and off its own platform. Sell the unit at £10 and the three-pack at £33, and the system may read the bundle as a worse deal than buying three singles, and suppress the Buy Box. The same happens when you raise the bundle price without touching the single item.
What to check:
- Effective per-unit price of the bundle against the single product. The bundle has to come out equal or better.
- Consistency with your own site and other channels. If the same bundle is cheaper on your own shop, that can weigh against you.
- Correct listing setup. A multipack needs its own ASIN with the quantity declared in the attributes, not a badly built variation of the single product.
- Price history. If the bundle sat at a very low price for weeks, that price becomes the benchmark you are measured against.
Step by step when you lose it
- Confirm you have actually lost it. Open the listing in a private window and on mobile. Seller Central's business reports give a Buy Box percentage per ASIN: check whether it has dropped or gone to zero.
- Work out if it is one ASIN or many. One points to price or competition. Many at once points to account or fulfilment. This fork saves you hours.
- Compare the total price. Your price plus delivery against the winning offer. Include active promotions and vouchers, which count too.
- Review stock and promised delivery window. A lead time left too long after a warehouse change is a very common and very invisible cause.
- Open the account health dashboard. Order defect rate, late dispatch, cancellations, valid tracking rate. Any one of them above Amazon's threshold takes you out of the Buy Box even with the best price. Check the current thresholds in Seller Central, as they get updated.
- Look for new sellers on the listing. And if there are any, find out who they are.
- Change one variable and wait. Price changes usually show within hours; account metric changes take weeks. Pull four levers at once and you learn nothing.
When it is price and when it is account health
The most reliable signal is scope. A price problem is surgical: it hits the ASINs where you have competition and leaves the rest untouched. An account problem is across the board: it kills the Buy Box on products where you are the only seller, and there price explains nothing. If you have lost the button on an ASIN that is exclusively yours, stop looking at prices and go straight to metrics and lead times.
How to monitor it without losing your mind
You do not need to sit refreshing the listing. This is enough:
- Weekly Buy Box percentage report by ASIN. It lives in Seller Central's business reports. Sort by revenue and look only at your top earners.
- Alerts on your top 20 ASINs. Any repricing or monitoring tool will do; so will a ten-minute manual check every Monday.
- A clear threshold. Below 90% Buy Box on an important ASIN, investigate. Below 70%, it is urgent.
- Monthly seller sweep per listing. To catch the intruder before they have spent two months eroding your price.
What does not work is watching total sales alone. A big ASIN losing the Buy Box can hide inside a good month from the rest of the catalogue, and by the time you notice you have already lost organic position.
What to do this week
- Download the Buy Box percentage report by ASIN for the last 30 days and sort by revenue. Flag everything below 90%.
- For each flagged ASIN, decide within two minutes whether the problem is across the board (account) or surgical (price and competition). Do not go further until it has that label.
- Check your account health dashboard and note which metric sits closest to its limit. That is the one that will cause trouble next month.
- List the sellers present on your ten main listings. If one you do not recognise appears, buy a unit and keep the invoice.
- Check the per-unit price of every bundle against the single item and fix the ones that come out worse.