Book excerpt: Due to various events, the availability of goods in retail is currently increasingly being restricted with the result that customers cannot find in food retail (FR) the products they wish to purchase because those products are sold out or not availa-ble for delivery. This situation is also termed Out of Stock (OoS). The reasons for the unavailability of products are often problems in connection with orders for goods, as well as the shelf-filling process within a store. According to literature, in those cases where a customer faces an OoS situation, the customer may postpone the purchase, purchase an alternate product, purchase the product in another store or not purchase at all. Depending on the customers reaction, this will result in a sales decline affecting the retailer and /or manufacturer differently. In these cases, customer reactions are influenced by various factors, such as brand loyalty, availa-bility of offered substitute products and many other factors. Within the scope of a survey, it was found that 36% of the customers predominantly reacted with the purchase of an alternate product of another brand to OoS. Also, 29% of the surveyed were willing to visit another store due to OoS.