Marketplace structure
Offer count is not seller diversity.
Many visible offers can still depend on one or two sellers. Concentration matters because a single seller’s pricing, stock, or policy change may reshape the observed market.
Identify distinct sellers
Count stable seller identities rather than storefront rows where evidence permits. The same seller may publish multiple variations or offers. Conversely, similar names do not prove common ownership. Missing identity should remain unknown instead of being merged or treated as unique.
Measure share within a defined set
Seller concentration depends on the comparable listing set and observation method. Report the total comparable offers, offers per identified seller, and unknown-seller count. A concentration statement about active supply is not automatically a statement about sales share.
Consider dependency mechanisms
Concentration may affect price stability, availability, fulfillment consistency, and exposure to account-level changes. Marketplace dependency also includes reliance on one channel’s visibility, rules, or data coverage. These are operational considerations, not proof that a seller or platform will fail.
Watch for false diversity
Bundles, variations, promoted duplicates, and multiple condition grades can make one seller appear as many alternatives. Normalize product identity and condition before interpreting the count. Document exclusions and retain the source observation time.
Keep demand separate
A concentrated seller set can coexist with high, low, or unknown demand. Without transaction evidence, do not convert dominance in active listings into a sales claim. The Falcon Opportunity methodology requires each conclusion to reference the evidence it actually uses.
Practical conclusion
Seller concentration analysis describes how visible comparable supply is distributed. It is most useful when identity quality, duplicate handling, unknown sellers, and the limits of active-listing evidence remain visible.