This document summarizes a case study of how a major US retailer used customer analytics to optimize their marketing budget. It involved (1) building a data-driven customer profile, (2) applying customer insights to optimize spending across channels, regions, and customers. Advanced customer clustering analyzed over 30 variables to segment customers into 12 highly differentiated groups with tailored marketing strategies, such as a "Brand Fanatics" group that represented 9% of customers but 30% of revenue.