Retail Media's Fifth Straight Year on Top
Retail media is the fastest-growing digital segment for the fifth year running — but the take-rate and margin opacity behind that growth deserves as much scrutiny as the headline numbers.
Retail media will remain the fastest-growing segment of digital advertising for the fifth consecutive year in 2026 — but the gap between its glowing growth rate and the opacity of how retailers actually price and measure these ads has never been wider. dentsu's May 2026 forecast puts retail media growth at 12.3% for 2026 and 11.4% for 2027 (revised down from the 14.1% dentsu projected in December 2025). The earnings data confirms the momentum is real. What advertisers are not getting, alongside the growth, is transparency.
The growth is enormous and verified
This is not a forecast built on hope. The platform earnings make the case directly:
Amazon reported advertising services revenue of $21.3 billion in Q4 2025 (reported February 5, 2026), with CEO Andy Jassy citing "Advertising growing 22%" — several press recaps round it to 23%. Full-year 2025 ad revenue passed $68 billion. eMarketer projects Amazon's retail media revenues will exceed $75 billion by 2028, more than $65 billion ahead of the next-largest network.
Walmart's global advertising business grew 46% year over year to nearly $6.4 billion in fiscal 2026 (ended January 31, 2026), per its SEC filing; Walmart Connect in the US was up 41% in Q4. CFO John David Rainey confirmed "fully a third of our profit in the most recent quarter was related to advertising and membership income."
Instacart reported advertising-and-other revenue of $286 million in Q1 2026 (ended March 31, 2026), up 16% year over year — its fastest ad-revenue growth since Q3 2023 — representing 2.8% of gross transaction value.
At the market level, eMarketer projects US retail media ad spending of roughly $71.09 billion in 2026, up from about $60.32 billion in 2025 — and that Amazon and Walmart together will capture over 89% of the incremental dollars. Retail media is now roughly 30% of US digital ad spend. The growth is genuine, and it is concentrating fast among a scaled few.
Why advertisers keep buying: first-party data and closed-loop measurement
The structural appeal is straightforward. Retail media networks (RMNs) sit on first-party shopper data — what real people actually buy, not modeled inference — and they offer closed-loop measurement, the ability to connect an ad impression to a verified purchase on the same platform. In a post-cookie environment where third-party signal is degrading, that combination of high-intent audiences and proof of sale is exactly what advertisers under CFO pressure want to buy. Retail media also collapses the funnel: ad, product page, reviews, and price all interact in a single environment.
The opacity problem hiding inside the growth
Here is what the growth charts do not show. RMN margins are extraordinary and largely undisclosed. Industry analysis pegs onsite retail media margins at 70–90% (the retailer owns the surface) versus 20–40% for offsite extensions — against traditional retail's 5–10%. That Walmart now derives a third of its operating profit from ads and membership is the structural signal: retail media is a profit engine, and the retailers controlling it have little incentive to open the books.
The transparency gaps are specific:
Take rates are not publicly disclosed. Neither Amazon, Walmart, nor Instacart publish the exact cut they take on media. The opacity is itself the story.
Measurement is self-graded. As eMarketer notes, RMNs offer "limited transparency. Retailers control the data and often restrict visibility into performance metrics, audience composition, and incrementality." AdExchanger's reporting on the broader ad-tech fee landscape describes "byzantine" fee structures, and at the IAB Tech Lab's 2026 Connected Commerce Summit, IAB's Collin Colburn flagged that retailers "don't all use the same lookback windows or measurement methodologies."
ROAS can take credit for sales that would have happened anyway. Industry surveys cited in 2026 trade analysis report that a large majority of advertisers don't fully trust retailer-reported metrics, and incrementality — not last-click ROAS — is now the KPI buyers say matters most. Incremental ROAS typically runs well below last-click figures.
The Cannes signal
The industry is formalizing retail media's status: Cannes Lions 2026 added retail media award subcategories, a recognition that the channel is now a creative and strategic discipline, not just a performance line item. WARC's 2026 World Cup analysis even framed retail media as the tournament's likely real winner, given its always-on, performance-led role as live-viewing attention fragments.
The operator's stance
Keep buying — but demand incrementality, not ROAS. Push every RMN to prove audience incrementality with holdout tests rather than accepting self-reported last-click returns.
Concentrate where scale is real. With Amazon and Walmart absorbing nearly all incremental dollars, the long-tail of RMNs must clear a higher bar to justify spend.
Treat the margin opacity as a negotiating reality. You are buying into a 70–90%-margin business that won't show you its take rate. Price that asymmetry into how aggressively you commit.
Bibliography
dentsu, "Global Ad Spend Forecasts May 2026" (27 May 2026). Link
Marketing Dive, "Amazon annual ad revenue passes $68B, boosted by full-funnel strategy" (Feb 2026). Link
Walmart, Q4 FY2026 earnings release, SEC 8-K (19 Feb 2026). Link
Instacart (Maplebear Inc.), "First Quarter 2026 Financial Results," PR Newswire (6 May 2026). Link
eMarketer, "Retail Media Ad Spending Forecast H1 2026." Link
eMarketer, "Retail Media Ad Spending Forecast and Trends H2 2025" (incremental-dollar concentration). Link