Epsilon's Leila Sheridan Makes the Case for Brand and Performance Working as One

Leila Sheridan is Head of Demand, Retail Media at Epsilon, and she came with a clear message: retail media has asked marketers to pick a side for too long.

Brand campaigns build long-term equity, but they resist measurement. Performance campaigns deliver clean numbers, but they leave the brand story untold. Sheridan’s session argued that this choice was never necessary.

Brand and performance need each other

Sheridan opened with an analogy built around Oasis. Noel Gallagher is the songwriter working in the background. Liam Gallagher is the frontman commanding the stage. “Both are essential, but too often they’re at odds,” she said. Brand and performance teams end up “working in silos” instead of moving together.

Brand teams build the audience connection that eventually drives a purchase. Performance teams capture the moment of conversion. Neither can fully prove its own contribution without the other.

Retail media has sold marketers a false choice for years, Sheridan argued. “Marketers have been told they have to choose brand for longevity or performance for immediate sales,” she said, “but marketers need both.” The split comes down to measurement. On-site advertising sits inside a retailer’s own environment. It’s competitive and limited to a handful of top listings, but a retailer can tie it directly to a sale. Off-site advertising reaches far more people across connected TV, audio, and display. Retailers have historically had no way to prove that exposure led to a sale later on.

First-party data closes the loop

Retailers can now share their own transaction data with brands. That lets advertisers link impressions, clicks, and views on off-site channels directly to purchases made online or in-store. This depends on knowing who the customer actually is, which is where identity resolution comes in.

Sheridan pointed to Epsilon’s Core ID identity network. ComScore independently validated it at 96 percent accuracy. It lets a retailer combine its own first-party data with external signals to recognize the same shopper consistently across touchpoints.

She gave a concrete example. One retail partner has 13 million online and in-store customers and two years of transactional history. Epsilon matches that data against its identity graph at a rate of 75 percent or higher. From there, brands can find those same shoppers across connected TV, online video, and off-site display, then reinforce the message once they land back on the retailer’s site.

Transaction data needs context

Sheridan was careful to flag the limits of purchase history on its own. She used a receipt from a Westfield Shopping Center visit as an example. A single high-value purchase, like an expensive bottle of whiskey bought in January, might suggest a high-net-worth shopper with a taste for spirits.

Then she offered a more personal case. Her nephew once bought a specific mascara as a one-off birthday gift for his young cousin. Looking only at his transaction history would misclassify him as a beauty shopper. “That context really matters,” she said. Enriching transaction data with demographic and lifestyle signals is what separates a useful targeting segment from a misleading one.

This combination lets targeting run from broad audiences, like luxury shoppers likely to respond well on a retailer such as John Lewis, down to individual SKU-level history, including shoppers who bought a specific brand years ago and have since lapsed. The same precision extends into measurement. Brands can track ROAS at the category, brand, and SKU level, run brand uplift studies, and even ring-fence stores nationally to analyze footfall around a campaign.

One measurement standard for both halves of the funnel

Sheridan closed by returning to her central theme. Once brands combine identity, transaction data, and off-site reach, they can measure true incrementality rather than assumed impact. They can attribute off-site exposure directly to both online and in-store purchases. “It’s not choosing between long-term brand and short-term sales,” she said. “It’s giving both.”

Retail media has spent years treating brand and performance as competing budgets. Sheridan’s session made the case for treating them as one measurable system instead.