The term open stock basically refers to items ordered by customers but not yet available in the warehouse. Like other types of inventory, such as safety stock or reorder point, open inventory is considered a business component. This is understood to mean a certain number of quantity units of an item that is not yet available in the warehouse or not available in sufficient quantity - in relation to the order backlog.
With the help of IT systems, this can be shown, for example, by means of availability displays in online stores; it can also be used to indicate expected delivery times based on empirical values.
Unlike safety stock, which is particularly important in the course of bottlenecks or special order peaks, open stock tends to indicate that there may be supply chain problems or that it is B or C goods that are only held in stock in marginal numbers.