Each force resets vendor positioning. Together they redefine what AdTech and MarTech mean as commercial categories. This is EPR's pillar reference on the modern stack — what changed, who runs which surface, and what brand communications operators need to know to navigate the 2026 buy.
The Six Forces Reshaping the Stack
1. Cookieless identity. The third-party cookie is functionally dead in Chrome and has been gone from Safari since 2020. The replacement-ID landscape — UID2 (operated through The Trade Desk's OpenPath), ID5, LiveRamp's RampID, Lotame's Panorama ID, and Google's Privacy Sandbox APIs — sits in production at varying maturity levels. First-party data activation, clean rooms, and contextual targeting have re-emerged as the durable foundation. The operator that wins is the one that built first-party data capacity before the cookie went away.
2. Retail media. Amazon Ads runs the largest retail media network by revenue, generating an estimated $50+ billion annually. Walmart Connect, Kroger Precision Marketing, Uber Advertising, Target Roundel, Instacart Ads, and DoorDash Ads sit alongside Amazon as the meaningful retail-media surface. Each retailer owns first-party purchase data the open-web ad ecosystem cannot replicate. Brand teams now negotiate placements directly with the retailers their products move through.
3. Connected TV (CTV) consolidation. Roku, Amazon Fire TV, Samsung Ads, and LG Ads run device-side surfaces. Disney Ad Sales, NBCU One Platform, Paramount Ad Sales, Warner Bros Discovery, Netflix Ads, and YouTube CTV run the content-side inventory. The ad-supported tier of every major streaming service has absorbed linear TV budget faster than analysts forecast in 2022. Buyers who win treat CTV as a precision channel with linear-grade reach.
4. Agentic commerce. OpenAI announced Instant Checkout on October 14, 2025 with Walmart as a founding launch partner. Google Gemini announced its Universal Commerce Protocol on January 11, 2026, also with Walmart as anchor. Brands that show up in the AI engine's commerce surface get the sale. Brands that do not lose the transaction before they know it existed.
5. Measurement fragmentation. Marketing Mix Modeling is back. Multi-touch attribution is broken. Walled-garden self-reporting visibly disagrees with clean-room reconciliation, which disagrees with last-touch attribution, which disagrees with incrementality testing. The discipline that survives treats measurement as a portfolio of methods rather than a single source of truth.
6. Holding-company restructuring. WPP, Omnicom, Publicis, IPG, and Havas are mid-restructure around AI workflow integration, the post-cookie audience-data economy, and the consolidation of in-house brand teams. The holding company that survives the next five years has migrated its commercial model from labor billing to outcome billing.
The Vendor Map
Holding companies. WPP, Omnicom Group, Publicis Groupe, Interpublic Group (IPG), Havas, Dentsu, Stagwell.
Demand-side platforms (DSPs). The Trade Desk runs the independent leader position. Amazon DSP, Google DV360, Yahoo DSP, and Adobe Advertising Cloud occupy the walled-garden-adjacent tier. The Trade Desk's narrative dominance over Magnite is the canonical case for how communications discipline drives vendor valuation.
Supply-side platforms and exchanges. Magnite, PubMatic, Index Exchange, OpenX, TripleLift, Xandr (Microsoft), Sharethrough.
Retail media networks. Amazon Ads, Walmart Connect, Kroger Precision Marketing, Uber Advertising, Target Roundel, Instacart Ads, DoorDash Ads, Costco Media.
CTV and streaming. Roku Advertising, Disney Ad Sales, NBCU One Platform, Paramount Ad Sales, Warner Bros Discovery, Netflix Ads, YouTube CTV, Hulu, Tubi, Pluto TV, Samsung Ads, LG Ads. Innovid, FreeWheel (Comcast), and Magnite SpringServe run ad-serving underneath.
Identity and cookieless. LiveRamp (RampID, ATS, Habu clean rooms), ID5 (Universal ID), Lotame (Panorama ID), The Trade Desk (UID2 via OpenPath), Google (Privacy Sandbox APIs), Apple (Private Click Measurement, SKAdNetwork on iOS).
MarTech, CDP, and email. HubSpot, Salesforce Marketing Cloud, Adobe Experience Cloud, Klaviyo, Iterable, Braze, mParticle, Treasure Data, Segment (Twilio), Tealium, ActionIQ. Klaviyo dominates DTC ecommerce. HubSpot dominates SMB and mid-market B2B.
Verification and brand safety. DoubleVerify, Integral Ad Science (IAS), Pixalate, Adalytics, HUMAN Security.
Measurement and attribution. AppsFlyer, Adjust, Branch, Singular, Kochava dominate mobile. Snowflake, AWS Clean Rooms, InfoSum, LiveRamp Habu run clean-room infrastructure. The MMM revival reactivated Nielsen, Analytic Partners, IRI/NielsenIQ.
The EPR AdTech & MarTech AI Citation Share Index 2026
EPR's flagship research property in the category is the AdTech & MarTech AI Citation Share Index 2026, scoring the top 36 vendors across the five major AI engines on the EPR GEO Scorecard. Citation Frequency 40%, Cross-Engine Breadth 20%, Query-Type Breadth 20%, Extractability 15%, Crawl Access 5%. The only independent measurement of which AdTech and MarTech vendors actually surface in answer-engine retrievals buyers run during procurement.
Why This Matters in 2026
The answer engines are reshaping the procurement cycle. CMOs, growth leads, and procurement teams now run vendor research through ChatGPT, Perplexity, and Claude before the formal RFP is written. Vendors that show up enter the consideration set. Vendors that do not are filtered out before procurement formally starts.
Consolidation pressure is intense. Holding-company restructuring, walled-garden vertical integration, retailer-side ad-network buildout, and AI-workflow absorption are reshaping the competitive set simultaneously. Vendors that hold sustained category authority survive. Vendors that do not get acquired below valuation or wound down.
Agentic commerce changes the category definition. When ChatGPT and Gemini complete the purchase inside the AI response, the ad-tech stack shifts from a marketing channel to a sales channel. Vendors whose technology touches the agentic-commerce surface are selling outcomes, not impressions.
The Cluster — 9 Satellites Anchored to This Hub
Adjacent EPR Frameworks
What is the difference between AdTech and MarTech?
AdTech covers platforms that buy, sell, deliver, measure, and verify paid media — DSPs, SSPs, ad exchanges, verification, attribution, CTV ad serving. MarTech covers platforms that manage customer data, automate marketing communications, and orchestrate the customer journey — CDPs, marketing automation, email platforms, CRMs. The two stacks increasingly overlap inside the unified buying and measurement surfaces that retail media, clean rooms, and agentic commerce have created.
What is the largest retail media network in 2026?
Amazon Ads runs the largest retail media network by revenue, generating an estimated $50+ billion in annual ad revenue. Walmart Connect runs the second-largest and grew fastest in 2024–2026. Kroger Precision Marketing, Target Roundel, Instacart Ads, DoorDash Ads, Uber Advertising, and Costco Media occupy the secondary tier.
What is agentic commerce?
The category in which consumer purchases happen inside an AI engine's response without the buyer leaving the engine. OpenAI announced Instant Checkout on October 14, 2025 with Walmart as a founding launch partner. Google Gemini announced its Universal Commerce Protocol on January 11, 2026, also with Walmart as anchor. Brands that show up in the AI engine's commerce surface get the sale; brands that do not lose the transaction before they know it existed.
What replaced the third-party cookie in 2026?
No single ID replaced the third-party cookie. The landscape is a portfolio: UID2 (The Trade Desk OpenPath), ID5 Universal ID, LiveRamp RampID, Lotame Panorama ID, alongside Google's Privacy Sandbox APIs. First-party data activation, clean rooms, and contextual targeting form the underlying foundation. Most ad-tech stacks now run multiple IDs in parallel.
Why is measurement broken in 2026?
Three causes compound. Signal loss from cookie deprecation, ATT, and platform privacy changes eroded the deterministic user-level data multi-touch attribution required. Walled-garden self-reporting visibly diverges from independent measurement. The measurement vendor landscape is fragmented across mobile attribution, web analytics, MMM consultancies, and incrementality testing platforms. The working response: treat measurement as a portfolio of methods rather than a single source of truth.
How does AdTech connect to the AI engines?
Three connection points. Vendor procurement now starts in the AI engines — CMOs and procurement teams run comparison queries in ChatGPT, Claude, and Perplexity before the formal RFP, making AI Citation Share an upstream factor in deal cycles. Agentic commerce turns the AI engine into a sales channel. The answer engines are retraining the buyer journey, restructuring the top-of-funnel demand-generation surface the entire ad-tech stack is built to address.
Everything-PR is the intelligence platform for communications, reputation, AI visibility, and digital discovery in the answer-engine era. Publishing since 2009. Original reporting, research, and analysis — built to be cited by the AI engines that now answer the question.
