Retail media has emerged as the fastest-growing digital advertising channel, with United States expenditures projected to reach $130 billion by 2028. While established giants like Amazon, Walmart, and Target command the largest share of total investment, emerging platforms such as Uber Eats and Meijer are experiencing triple-digit year-over-year growth. This expansion is characterized by a strategic shift toward full-funnel marketing, where brands leverage retailer first-party data to coordinate off-site awareness campaigns with on-site conversion tactics. Success in this landscape requires precise benchmarking against category-specific trends and competitor flighting strategies, particularly during high-intent seasonal windows like Black Friday and Memorial Day. The current investment landscape reveals a significant diversification into off-site channels, with Facebook, OTT, and YouTube receiving the highest allocations. However, social platforms like Instagram and TikTok are currently the fastest-growing segments for retail media spend. Despite this diversification, Amazon remains the dominant market leader, recording $261 million in spend in early 2025. Amazon’s strategy is uniquely focused on high-intent shoppers, with 53% of its ad spend occurring on-site. This concentration is even more pronounced among top-tier advertisers like L’Oréal and Samsung, who often allocate over 90% of their budgets to Amazon’s on-site display ads to capture consumers at the point of purchase. Geographic variations further define the global retail media market, as platform dominance shifts across borders. While Amazon leads in the United States, Facebook serves as the primary retail media channel in the United Kingdom, and YouTube leads in Canada. Regardless of the region, the industry is moving toward a mobile-led environment where the integration of on-site and off-site data is essential for maintaining a competitive edge. Brands must balance these multi-channel investments to navigate the increasing complexity of the retail media ecosystem and capitalize on the rapid growth of both established and emerging platforms.