Out of stock occurs when a retailer has zero available inventory of a product, making it unavailable for purchase. In ecommerce, this typically means the "Add to Cart" button is disabled or the item is marked as unavailable, potentially with a "notify me" option for restocking alerts.
OOS events are costly: customers may abandon their purchase entirely, buy from a competitor, or lose trust in the brand's reliability. Studies suggest out-of-stocks can reduce customer satisfaction scores and increase churn rates significantly.
Tracking competitor out-of-stock patterns provides valuable intelligence. Frequent OOS on popular items may indicate supply chain issues, strong demand exceeding expectations, or intentional scarcity marketing. Brands with consistently low OOS rates demonstrate operational excellence and demand forecasting accuracy.