Retail media platforms represent a $100B+ global opportunity, projected to reach $109.4 billion by 2027. Building one requires five core components: data clean rooms for privacy-safe targeting, identity resolution systems, cross-channel attribution, ad servers, and unified on-site/off-site/in-store architecture. First-party data delivers up to 6x higher ROI than traditional targeting. Retailers face a build vs. buy decision—custom development takes 12-18 months and costs $2-5M, while partner solutions launch in 3-6 weeks for $100K-$500K. Successful launches start with beta testing 5-10 advertisers, implement CPC/CPM/ROAS-based monetization models, and use closed-loop measurement to connect ad exposure directly to purchases. On-site retail media delivers 80-90% margins versus traditional retail's 10-20%.
