A catalog with twenty products can still depend on two. If those two produce most of the contribution, a stockout or product problem can affect the business much more than the catalog count suggests.
Alfredo Roselli's catalog-concentration review starts with a simple question: how much of the business do the top products carry? The more useful follow-up is why that share changed. Winners gaining sales and weaker products losing sales can both increase concentration, but they call for different responses.
Choose the measure before ranking products
Start with revenue by ASIN for a consistent date range and marketplace. Rank products from largest to smallest, then calculate the share represented by the top one, three and five. If you have fewer than five products, do not treat a 100% top-five share as a discovery.
For each group, divide its combined revenue by total catalog revenue. Keep the underlying dollars beside the percentage. A share can rise even when the products in that group do not grow.
Next, repeat the analysis using contribution dollars if reliable cost data is available. Define contribution consistently: revenue less the product, selling and advertising costs included in your model. This is not necessarily net profit. A high-revenue product with thin economics may carry less of the business than a smaller, more profitable product.
Keep product groupings consistent
Choose whether you are measuring child ASINs, parent families or commercial product lines. Variations of the same product may share a supplier, listing risk or production constraint. Counting every color as independent diversification can hide that exposure.
Keep a product-family view alongside the ASIN view where it matters. Record launches, discontinued items and grouping changes. Otherwise, a renamed family or a different export level can look like a real change in the business.
Separate winners growing from the remainder shrinking
| Illustrative scenario | Top three revenue | Other revenue | Top-three share |
|---|---|---|---|
| Starting period | $60,000 | $40,000 | 60% |
| Winners grow | $80,000 | $40,000 | 66.7% |
| Other products shrink | $60,000 | $30,000 | 66.7% |
The ending concentration is the same in the last two rows. In one case total revenue reaches $120,000; in the other it falls to $90,000. The percentage cannot tell those stories apart.
Track two comparisons: today's top products against the previous period, and the previous period's top products against today. Holding the original group fixed helps reveal what happened to those products. Re-ranking shows whether different products are taking their place. Label each view so changing membership does not obscure the explanation.
Handle contribution percentages carefully
Contribution rankings can differ from revenue rankings because margins and advertising requirements differ. Use the actual period's contribution where possible, rather than multiplying all sales by a single assumed margin.
Loss-making products complicate the share calculation. If the winners contribute $20,000 and the rest lose $5,000, total contribution is $15,000. The winners represent 133.3% of the net total. That is mathematically possible; it tells you losses elsewhere reduce the total. Do not force the number below 100% or call it an error.
Show profitable-product contribution, loss-making-product contribution and the net amount separately. When total contribution is zero or negative, a top-three share of that total is not a useful concentration score. Report dollar exposure instead. Our ACOS and contribution guide explains the product economics behind this distinction.
Turn the finding into an operational review
For the products carrying the business, review stock cover, replenishment lead time, supplier dependence, returns and listing health. A concentrated catalog with dependable supply has different risks from one relying on a single uncertain shipment.
For the remaining catalog, identify why sales or contribution declined. Was the reduction deliberate? Did inventory run out? Were ads reduced because the products were unprofitable? Did prices, demand or conversion change? Restoring every declining SKU is not automatically the right decision.
Add advertising dependency to the review. A major product with flat sales, rising attributed share and shrinking contribution has several linked questions to answer. Cutting its budget solely because it looks concentrated would skip the diagnosis.
Choose an action that fits the cause
If strong products are growing profitably, protect availability and test the next credible product opportunity. If the remainder is declining unintentionally, prioritize recoverable products by contribution potential and the cost of fixing the problem. Use the PPC optimization workflow where campaign execution is the constraint.
There is no universal concentration percentage every brand should meet. A focused brand and a broad catalog have different business models. The useful outcome is knowing the exposure, understanding the movement, and assigning an action before a single product problem becomes a company-wide surprise.
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