In an Era of Accountability, Third-Party Measurement is Retail Media Networks’ Biggest Asset, Not Enemy

Heading into 2026, budgets/resources are the top challenge for marketers, according to InMarket’s Predictions Report. As retail media networks (RMNs) remain a popular line item in every CPG marketer’s playbook, the ability to better understand the impact of this spend across key outcomes like incremental sales, visits and return on advertising spend (ROAS) is critical.

Every RMN operating with its own measurement infrastructure makes it nearly impossible for brands to understand campaign performance holistically and compare outcomes, which increases skepticism about the results RMNs share. When retailers view third-party measurement as an ally, they can build greater trust, foster longer-term relationships and, ultimately, unleash the full potential of RMNs’ reach, including the impact the advertising has in driving incremental sales elsewhere.

Here are three of the biggest opportunities presented by third-party measurement as accountability remains at center stage:

1. The Halo Effect: Showcasing Off-Premise Impact in a Fragmented Shopping World

Persistent economic uncertainty has transformed shopping into value-driven treasure hunts. From holiday shopping to weekly grocery hauls, shoppers are visiting more stores and retail channels to find the best deals. In fact, the number of stores shoppers visited increased by 31 percent in Q1 2025 compared to Q1 2023.

Limiting measurement to the four walls of your store prevents brands from understanding the “halo effect” of your RMN’s advertising value in this fragmented environment. If a shopper sees a RMN ad for M&Ms or Reese’s Peanut Butter Cups in their go-to grocery store, but ends up purchasing a bulk-sized bag at their nearby warehouse club, without a holistic, third-party measurement infrastructure in place, RMN reporting won’t account for that incremental purchase. Enhanced measurement tells the story of conversion off-premise (aka the “halo effect”).

2. Expanding the Non-Endemic Opportunity by Proving Results and Providing Confidence

Non-endemic advertising presents a significant opportunity for retailers to grow ad revenue.

However, many brands demand third-party measurement to provide that outside confidence in results — they can’t just take your word for it or your in-house reporting as the end-all, be-all.

Dining is a great example of the non-endemic opportunity. Notably, 32 percent of shoppers stopped at a limited-service dining chain (quick service, fast casual or casual dining restaurant) after visiting a big-box, grocery, discount/dollar or warehouse club store between August 2025 and October 2025, according to InMarket research. In fact, some of those dining options are available within the retail locations as well. As a result, this makes those in-store shopping moments a prime time to reach frequent diners. There are also unique opportunities for dining advertisers to improve the overall customer experience, like highlighting new offerings or value meals during the shopping experience.

But to get there, brands like the dining advertiser as well as retailers must be open and willing to work with an independent third-party measurement partner of choice. Doing so builds trust with non-endemic advertisers and can help accelerate advertising investments for the RMN.

3. Improving Optimization and Competitive Insights With Holistic Measurement

By providing a complete picture of stops on that value-driven treasure shopping hunt and the “halo effect,” third-party measurement can also unlock critical competitive insights for retailers. This can not only help improve effectiveness and inspire smarter strategies in the future, but also enable optimization in response to shifts in shopping behavior while a campaign is in-flight to maximize incremental outcomes.

For example, if RMN reporting for a soft drink brand revealed a spike in purchases at a nearby discount/dollar chain after seeing the RMN ad in your store, could optimizing towards creatives that highlight better value or promotional deals help win back share of sales at your chain? Holistic measurement doesn’t just help retailers better assess and optimize performance for in-flight campaigns, it provides additional 360-degree insights. This ensures retailers and brands alike understand how consumer trends are changing across categories and retail channels as economic uncertainty continues in 2026.

The biggest takeaway for retailers? Don’t sell yourself short by holding back from partnering with third-party measurement on RMN campaigns. The reality is that more and more advertisers, especially in non-endemic categories, demand it and it can become one of your greatest assets in proving the “halo effect” your media brings to advertisers.

Be at the forefront of this adoption and do what’s right by the brand (it’s going to happen inevitably). You’ll not only become one of the first to help clients improve their measurement capabilities, you’ll also ensure you accurately account for every dollar you’ve earned clients across channels, while gaining deeper insights into the economic and competitive landscapes in the process. A win-win combination.

Gerry Joyce is vice president, practice leader of retail at InMarket, a leader in real-time marketing and measurement.