Answer
Several channels can reduce the same stock almost simultaneously. Purely periodic synchronisation always has a time window in which values are out of date. When demand is high, more orders may therefore be accepted than goods are available. A leading available stock figure, fast order intake, reservation rules and suitable safety stock reduce this risk.
Technically, the order of states matters: is stock reserved when the order is placed or only reduced on shipping? Can a failed order be reprocessed without a duplicate reservation? How are cancellations and returns handled? For particularly scarce items, a binding reservation in the central system may be necessary. An absolute guarantee against overselling would not be credible when external marketplaces and delayed APIs are involved. The goal is a traceable model with monitored discrepancies and a defined clarification path.
As of 3 September 2026
Further reading
Related topic: Online shop