Amazon DSP vs. Walmart DSP in 2026: Which Wins for Retail Media?

Retail media has become the fastest-growing ad channel in e-commerce, and the two dominant players — Amazon DSP and Walmart DSP — are pulling brand budgets in opposite directions. Amazon still commands the lion’s share of retail media dollars, but Walmart’s demand-side platform has grown aggressively since its 2023 overhaul, integrating Walmart Connect inventory, offsite display, and first-party purchase data from 250 million weekly shoppers. For DTC founders, marketplace operators, and agency media buyers, the question in mid-2026 is no longer whether to use retail media DSPs — it’s which one earns the incremental dollar.

What Are the Core Differences Between Amazon DSP and Walmart DSP?

Amazon DSP gives advertisers programmatic access to Amazon’s owned-and-operated properties — including Amazon.com, IMDb, Freevee, Twitch, and the Fire TV ecosystem — plus offsite inventory via third-party publishers and apps. It runs on Amazon’s first-party purchase signal dataset, which covers roughly 300 million active customer accounts globally. Minimum managed-service spends typically start at $50,000 per quarter, though self-service access through Amazon Ads Console has lowered the barrier for mid-market sellers.

Walmart DSP, powered by The Trade Desk’s infrastructure since a 2021 integration deepened in 2024, plugs Walmart’s first-party data into a broader open-internet buying environment. Advertisers can reach Walmart shoppers across Walmart.com, the Walmart app, in-store digital screens, and offsite display and video. Critically, Walmart DSP’s floor is lower: managed-service minimums run around $25,000 per quarter in most agency agreements, and self-service access is available through the Walmart Connect portal with no formal minimum.

How Do the Audience Scale and Data Quality Compare?

Amazon’s data moat is still formidable. With $554B in net product and service sales reported in 2025, Amazon’s purchase graph covers categories from electronics to grocery at a depth no other retailer can match. Its audience segments — “in-market for premium dog food in the last 30 days,” for instance — are derived from actual transaction data, not modeled behavioral proxies.

Walmart’s pitch is differentiation, not defeat. Walmart Grocery is the single largest grocery retailer in the U.S. by volume, and its DSP lets CPG brands reach buyers whose purchase behavior Amazon simply doesn’t see. For household consumables, personal care, and food and beverage categories, Walmart’s first-party signal is arguably more relevant.

“We ran a 90-day head-to-head for a mid-sized CPG client in the cleaning products category. Walmart DSP delivered a 2.3x ROAS on offsite display versus Amazon DSP’s 1.8x — because Walmart’s grocery buyers are just a more accurate proxy for the audience we needed,” said Megan Tran, VP of retail media at Arc Commerce Agency, a Chicago-based shop managing roughly $40M in annual media spend.

Amazon counters with sheer scale: its DSP reaches an estimated 96% of U.S. internet users through its publisher network, compared to Walmart DSP’s estimated 70-75% reach via The Trade Desk’s open exchange.

What Do Pricing and ROAS Look Like in Practice?

CPMs on Amazon DSP for display inventory in competitive categories — electronics, beauty, apparel — have climbed to $8–$14 for audience-targeted placements in Q1 2026, up roughly 18% year-over-year according to agency benchmarks compiled by Tinuiti’s retail media team. Video CPMs on Fire TV and Freevee now regularly clear $25–$35 for non-skippable 15-second units.

Walmart DSP CPMs sit meaningfully lower. Display placements targeting Walmart’s first-party audiences run $5–$9 CPM, and onsite sponsored display equivalents are even tighter. The Trade Desk integration means buyers get transparent auction pricing rather than Amazon’s more opaque managed-rate card.

ROAS benchmarks vary sharply by category and attribution window. Agencies using a 14-day last-touch window report:

• Amazon DSP display: 1.6x–3.2x ROAS across non-endemic brands; 3.5x–6x for endemic Amazon sellers in high-intent categories
• Walmart DSP display: 1.9x–3.8x ROAS for grocery and consumables; 1.4x–2.5x for categories where Walmart’s shopper index is weaker (e.g., electronics, luxury)
• Amazon DSP video (OLV): 1.2x–2.1x ROAS — primarily upper-funnel, harder to close-attribute
• Walmart DSP video (CTV via TTD): 1.1x–1.9x ROAS, with stronger lift metrics in brand awareness studies

“The ROAS numbers on Amazon DSP look better on paper for endemic brands, but you have to factor in the CPM premium and the minimum commitment. For a $2M annual media budget, Walmart DSP lets you test and learn at lower risk,” said Carlos Medina, head of programmatic at Bobsled Marketing, whose team manages retail media for over 60 Amazon and Walmart sellers.

How Do Reporting, Attribution, and Measurement Stack Up?

This is where Amazon DSP still holds a structural advantage. Amazon’s closed-loop attribution ties DSP impressions directly to Amazon.com purchases with same-cart, same-ASIN granularity. For sellers whose primary revenue channel is Amazon, this creates a measurement environment that third-party attribution tools — Triple Whale, Northbeam, Rockerbox — struggle to replicate cleanly.

Walmart DSP’s measurement story has improved materially since its 2024 partnership with Circana (formerly IRI) for in-store sales lift measurement, but the closed-loop is less tight. Offsite display campaigns can be matched to Walmart.com conversions, but brick-and-mortar lift attribution requires a separate Circana study, typically adding $15,000–$40,000 in measurement costs for CPG brands that need it.

Both platforms now support incrementality testing. Amazon rolled out its Incrementality Measurement dashboard in late 2025, giving DSP advertisers ghost ad holdout groups at no added cost for campaigns above $100K. Walmart DSP offers similar holdout testing through The Trade Desk’s built-in A/B framework.

Which Platform Wins for Amazon Sellers, DTC Brands, and CPG Operators?

The honest answer is that platform selection should follow audience fit, not brand preference. Here’s how the segmentation breaks down in practice:

• Endemic Amazon sellers (brands selling primarily on Amazon.com): Amazon DSP is the clear choice. Closed-loop attribution, in-market audience precision, and the ability to retarget product detail page visitors without leaving the Amazon ecosystem are hard to replicate.
• DTC brands with Shopify storefronts: Amazon DSP’s offsite reach is broad, but the attribution back to a Shopify site requires pixel-based tracking that’s noisier post-iOS. Walmart DSP’s Trade Desk backbone integrates more cleanly with third-party attribution tools and is often easier for DTC teams already running TTD or DV360.
• CPG brands in grocery, household, and personal care: Walmart DSP’s first-party grocery data is a genuine differentiator. Brands that rely on Walmart Supercenter velocity to hit trade spend targets should be running Walmart DSP regardless of what else is in the mix.
• Brands new to retail media with sub-$500K annual budgets: Walmart DSP’s lower minimums and more transparent pricing make it a better testing ground. Amazon DSP managed service at $50K/quarter is a meaningful commitment for a first-time retail media buyer.

What Does the Competitive Landscape Look Like Heading Into H2 2026?

Both platforms are pushing into CTV and live commerce ad formats aggressively. Amazon’s acquisition of additional FAST channel inventory through Freevee and its expanded Thursday Night Football sponsorship packages have made its video offering significantly more premium in 2026. Walmart, meanwhile, launched shoppable CTV units in Q1 2026 that allow viewers to add items to a Walmart cart directly from a smart TV ad — a format that early testers report is generating 0.8%–1.4% conversion rates on direct response campaigns, well above standard OLV benchmarks.

The Trade Desk partnership gives Walmart DSP a roadmap advantage: as TTD expands its OpenPath direct publisher relationships and UID2 identity infrastructure, Walmart DSP advertisers get access to a broader, more privacy-resilient targeting stack than Amazon’s proprietary walled garden can offer in third-party environments.

“Amazon DSP is still the default for our Amazon-first clients, but I’ve had three conversations this quarter with brands asking whether they should shift 20–30% of their retail media budget to Walmart. A year ago, that question wasn’t coming up,” said Tran.

Amazon reported $56.2B in advertising services revenue in 2025 — a 19% year-over-year increase — with DSP representing a growing slice of that alongside sponsored ads. Walmart’s advertising revenue crossed $4.4B in FY2025, up 27% year-over-year, with Walmart Connect explicitly cited by CFO John David Rainey as a high-margin growth lever in Q4 2025 earnings commentary.

Head-to-Head Comparison: Amazon DSP vs. Walmart DSP

The bottom line for media buyers heading into the back half of 2026: Amazon DSP remains the dominant platform by scale and attribution fidelity for Amazon-centric sellers. But Walmart DSP’s lower cost of entry, open infrastructure, and grocery-category data advantage make it a serious allocation for any brand that competes in physical retail or is trying to diversify off Amazon’s walled garden. The smartest operators aren’t choosing — they’re splitting budgets deliberately and using incrementality holdouts on both platforms to let the data make the argument.