<p>In this study, an empirical analysis was used to assess the importance of identifying super-loyal customers. The purchase history data of supermarket cardholders aggregated by firm, customer, and brand for the 2019 calendar year, were used in the analysis. In this study, 28 product categories were selected and analysed across firms and brands based on a cumulative purchase share of up to 85% in each category. In the analysis model, we applied a zero-inflated gamma distribution, because the data used for the analysis included a large number of no-purchase records and were skewed in the positive direction. To identify super-loyal customers, we used the upper 1% of this distribution, according to the indicators used in financial risk management. The results show that in categories where brands have an oligopoly, there is a positive relationship between monetary share and super-loyal customer criteria. However, in categories where brands are in competition, the smaller brands have a higher ranking than the larger brands, indicating that smaller brands rely more heavily on super-loyal customers and face a greater risk from customer attrition. In addition, the proposed method can be used to estimate the criteria for determining super-loyal customers simultaneously with the average value and standard deviation. This enables it to be used for a comprehensive brand evaluation.</p>