Retail media networks: navigating measurement and fragmentation for US agencies

The Exploding Retail Media Landscape: Challenges for US Agencies in 2026

The US retail media landscape is experiencing an unprecedented surge, with US retail media ad spend is forecast at $71.09 billion in 2026, according to eMarketer’s H1 2026 forecast. However, other projections, such as by NIQ, estimate US retail media spend to reach $107.6 billion in 2026. This remarkable growth significantly outpaces the broader digital ad market, creating both immense opportunity and formidable challenges for US agencies. While the potential for reaching consumers at the point of purchase is clear, agencies are grappling with an increasingly complex environment.

A primary concern is the accelerating fragmentation of the ecosystem. Advertisers are currently managing an average of six distinct retail media networks, a number projected to nearly double to 11 by the close of 2026. This proliferation introduces significant operational hurdles and measurement complexities. Furthermore, the market is heavily dominated by a few giants; Amazon and Walmart Connect are expected to absorb over 89% of net-new retail media investment dollars this year, making strategic allocation and diversification critical. Navigating this fragmented yet concentrated landscape, while ensuring effective measurement, defines the core challenge for agencies in 2026.

Key Insight:
Agencies are facing a rapid expansion in retail media networks. Advertisers currently manage an average of six platforms, a figure expected to rise to 11 by the end of 2026, intensifying the need for streamlined management and robust measurement strategies.

Navigating the Measurement Maze: Incrementality, Trust, and Data Discrepancies

As US retail media ad spend approaches $70-71 billion in 2026, the landscape of measurement presents significant hurdles for agencies. Despite the rapid growth, a stark reality emerges: only 15% of marketers report being very or extremely effective at measuring retail media performance this year. This challenge is further amplified by the fact that 75% identify incrementality—understanding the true causal impact of ad spend—as their biggest measurement concern.

The discrepancy between reported and actual performance is a critical issue. Incremental Return on Ad Spend (ROAS) typically runs 30% to 60% below the last-click ROAS reported directly by retail networks. This significant gap fuels a widespread skepticism, with a staggering 94% of advertisers expressing distrust in retailer-reported metrics. Such data discrepancies undermine confidence and make it difficult for agencies to accurately assess campaign effectiveness, optimize spend, and justify investments to clients.

The implications of this distrust are profound, leading to inefficient budget allocation and a lack of clear strategic direction. Agencies urgently need independent verification and unified measurement solutions that can cut through the noise of disparate network reporting. Establishing a single source of truth is paramount to unlocking the full potential of retail media and ensuring that every dollar spent drives measurable, incremental value.

• ✓ Seek independent verification for reported metrics.
• ✓ Prioritize solutions offering unified, cross-network measurement.
• ✓ Focus on incrementality testing to understand true ad impact.
• ✓ Develop robust internal frameworks for data validation.

Strategic Spend: Diversifying Beyond Amazon and Walmart Connect

While the retail media landscape in 2026 is undeniably shaped by the colossal presence of Amazon Ads and Walmart Connect, agencies face a critical strategic imperative: looking beyond these giants. Amazon Ads alone is estimated to capture $88.6 billion in the US in 2026. The $56.5 billion figure was a projection for Amazon Ads global revenue in 2025., and together with Walmart Connect, these two platforms absorb over 89% of net-new retail media investment dollars. This concentration of spend, while reflective of their market power, also highlights a significant risk for agencies that do not diversify their strategies.

The operational and measurement fragmentation already challenges advertisers, who manage an average of six retail media networks, a number projected to grow to 11 by the end of 2026. Over-reliance on just two dominant players can exacerbate these challenges by limiting reach and neglecting valuable consumer touchpoints across the full purchase journey.

Agencies must proactively explore emerging networks to capture a broader share of consumer attention. A significant growth area lies in in-store media, which is crucial given that Approximately 83-84% of purchases in 2026 are expected to occur in physical stores. For instance, U.S. Census data for Q3 2025 indicates that e-commerce accounted for 16.4% of total retail sales, meaning 83.6% occurred in physical stores. Integrating programmatic retail media into these physical environments offers untapped potential for reaching consumers at the point of decision.

Strategic Insight

Diversifying retail media spend beyond Amazon and Walmart Connect is key to unlocking full-funnel opportunities. Consider emerging networks, especially programmatic in-store media and shoppable CTV, to reach the 76% of consumers making purchases in physical stores and to build comprehensive campaigns.

Furthermore, the expansion of programmatic retail media into channels like shoppable Connected TV (CTV) advertising is becoming a cornerstone of full-funnel retail media strategies. These channels allow agencies to engage consumers earlier in their purchase journey, moving beyond last-click attribution and addressing the widespread distrust in retailer-reported metrics by focusing on true incrementality.

Adapting Agency Talent and Technology for a Fragmented Future

The burgeoning retail media landscape, characterized by rapid expansion and the proliferation of networks, presents significant internal challenges for US agencies. With advertisers managing an average of six retail media networks today, a figure projected to reach eleven by the close of 2026, the operational strain is undeniable. Each network often demands distinct knowledge, platform proficiency, and data interpretation skills, leading to considerable fragmentation in talent requirements.

Agencies must cultivate specialized teams capable of navigating diverse platforms, from Amazon Ads, estimated to be the largest US retail media network in 2026, to emerging players. Interpreting complex, often disparate data from these varied sources is critical, especially given that only 15% of marketers report effective measurement, and 94% express distrust in retailer-reported metrics. This necessitates a shift towards robust analytical capabilities to verify performance and understand true incrementality.

The operational inefficiencies stemming from managing numerous disparate networks are substantial. Manual data consolidation, varied reporting interfaces, and the need to toggle between multiple systems consume valuable resources and hinder a holistic view of campaign performance. To counteract this, agencies are increasingly turning to technological solutions. Unified platforms and data aggregators offer a path to streamline workflows, centralize campaign management, and provide a more cohesive perspective across multiple retail media networks.

Ultimately, continuous learning and upskilling for agency teams are paramount. As retail media evolves to include channels like in-store media and shoppable Connected TV (CTV) advertising, fostering a culture of ongoing education ensures agencies remain agile and effective in this dynamic environment.

• ✓ Invest in specialized talent for diverse retail media platforms.
• ✓ Prioritize training on advanced analytics and incrementality measurement.
• ✓ Implement unified platforms and data aggregators to streamline operations.
• ✓ Foster a culture of continuous learning and upskilling for all team members.

Unifying Retail Media: A Strategic Roadmap for US Agencies

The projected US retail media ad spend approaching $70-71 billion in 2026 highlights a landscape of both opportunity and complexity. Agencies currently manage an average of six networks, poised to grow to 11, leading to significant operational and measurement fragmentation. With only 15% of marketers effective at measuring performance and 94% distrusting retailer-reported metrics (where incremental ROAS can be 30-60% lower), a unified, integrated approach is paramount.

To navigate this, US agencies must strategically invest in independent measurement tools to accurately assess incrementality. Fostering cross-functional talent capable of advanced analytics and retail dynamics is crucial. Developing strategic partnerships across diverse retail media networks, encompassing growing areas like in-store media (76% of 2026 purchases) and shoppable CTV, will expand reach. Furthermore, agencies should advocate for industry-wide standardization in metrics and reporting to build trust and coherence. By adopting these strategies, agencies will be indispensable navigators for brands in this evolving ecosystem.