Why Long-Tail Advertisers Are Becoming Retail Media’s Biggest Growth Engine

In today’s episode I dig into a surprising and quietly powerful engine of growth for retail media networks: long-tail advertisers. While major CPG brands continue to cap their RMN partnerships at around six networks, retailers are pouring investment into Amazon and Walmart-level capabilities, hoping to win those national budgets. But the ceiling isn’t moving… so where’s the growth coming from?New data from Pentaleap's 2025 Sponsored Products Benchmark Report shows exactly where the action is. Retailers who are activating their long-tail ecosystems — smaller brands and third-party sellers — are seeing significant increases in impressions, revenue, and advertiser participation. I break down the numbers, the retailers leading the charge, and why the ability to scale thousands of smaller advertisers may be the single biggest opportunity for RMNs going into 2026.This episode is sponsored by Mirakl AdsTimeline[00:40] – Why major CPG brands are capping their retail media network relationships[02:00] – The operational challenges that limit RMN expansion for large advertisers[03:00] – How long-tail advertisers are emerging as a critical growth driver for RMNs[03:26] – Examples of retailers seeing momentum from activating smaller brands and sellers[04:19] – The role of third-party marketplaces in expanding advertiser participation[05:42] – Why RMNs need new infrastructure to effectively support thousands of long-tail advertisersLinks & ResourcesRead my articles:Inside Mars's Retail Media Investment MatrixHow Can RMNs Tap Upper-Funnel Brand BudgetsDownload Mirakl's Rakutren France case studyRead the new Forrester Consulting study commissioned by Mirakl - Combine Retail Media and Marketplaces to Unlock the Next Growth EngineGet Pentaleap's H2 2025 Sponsored Products Benchmarks ReportI'll be diving into the findings of the Pentaleap H2 2025 Sponsored Products Benchmark report with Pentaleap co-founder and CEO Andreas Reiffen on Thursday next week at 11AM ET! Join us LIVE here Are you based in Atlanta or plan to be in the ATL area on Weds Dec 3rd? Join me and a couple dozen of your new retail media industry besties for a festive happy hour! Register hereSubscribe to Retail Media Breakfast Club's daily newsletterFollow Kiri on LinkedIn