According to embodiments of the present invention there is provided a computer-based method and a computer program product for automatically sorting customers who make purchases from merchants using a credit card. The computer-based method includes the following steps. An adjusted index is calculated for a customer based on an amount of money the customer spent across merchants during a time period. The adjusted index is compared to a cut-off value. The customer is classified based on the comparison of the adjusted index to the cut-off value. In an embodiment, the method also includes re-classifying the customer based on at least one of (i) information about the merchants, or (ii) a number of transactions in a predetermined industry.