Company Profile / Commerce Marketing
The Company That Turned the Checkout Line Into a Media Channel
Mars United Commerce spent 50 years learning how people actually shop. In 2024, Publicis paid a reported $600 million to own that knowledge.
Most of advertising is obsessed with the top of the funnel - the billboard, the big idea, the ad that makes you feel something on the couch. Mars United Commerce built a company on the least glamorous part instead: the two seconds when a person standing in an aisle, or scrolling a product page, decides to actually buy. It is a specialty the industry now calls commerce marketing, and this Michigan firm has been practicing it since 1973, when almost nobody else thought the shelf was worth a strategy.
That head start turned into scale. By the time the company rebranded from The Mars Agency to Mars United Commerce in May 2024, it employed roughly 1,000 people across about 14 hubs, served more than 100 of the world's largest brands, and called itself the largest independent commerce marketing company in the world. Four months later it stopped being independent: in September 2024, Publicis Groupe acquired it in a deal reported at around $600 million.
A founder named Marilyn - and a platform named after her
The name confuses people. Mars has nothing to do with the candy company or the planet. It traces back to Marilyn Barnett, who founded the agency in 1973 and is widely credited with creating shopper marketing as a discipline. The firm's most quietly clever move is that its proprietary technology platform is also named Marilyn - a piece of software carrying the founder's name into the age of retail media and the digital shelf.
Marilyn, the platform, is described inside the company as "the great connector of data, intelligence, and results." In practice it pulls together the messy inputs of modern commerce - retailer sales data, media spend across dozens of vendors, digital shelf metrics, marketplace performance - and turns them into something a brand manager can act on. It includes a Commerce Marketing Mix Model built to weigh analytical truth against real-world performance, an ecommerce insights layer that folds in sources like Amazon Marketing Cloud, and a module called VendorFusion that streamlines retail media network operations from planning through deployment.
The reason a platform matters in a business that is, at heart, a services firm comes down to a single word retailers and brands both use constantly: measurement. Commerce spending is scattered across a growing thicket of retailer media networks, each reporting differently, and the perennial complaint is that nobody can say cleanly what worked. A tool that ingests, normalizes, and visualizes all of it - then attributes results back to spend - is the difference between advising a client and proving to them the advice paid off. Marilyn is Mars United's answer to that, and it is also the asset an acquirer cannot easily replicate by hiring people.
Our core mission is to make the business of our clients better today than it was yesterday. Rob Rivenburgh, Global CEO
What the company actually sells
Mars United Commerce organizes its work into four disciplines. On their own each is a service line; together they are meant to cover the whole path a shopper takes from consideration to conversion, online and in a physical store.
Strategy & Analytics
Commerce strategy, shopper insights, market analysis, and the measurement that tells a brand whether any of it worked.
Digital Commerce
Retail media, ecommerce, and digital shelf management across Amazon, Walmart, and other marketplaces.
Content & Experiences
Creative content, brand activation, and shoppable experiences designed to convert, not just to be admired.
Retail Consultancy
Field-based teams positioned near major retailers, advising on assortment, execution, and customer development.
The retail consultancy piece is the one that reveals the company's character. Rather than run everything from a single headquarters, Mars United built what it describes as the industry's first field-based network of retail consultancy hubs - people stationed close to the retailers they serve. In a business where knowing how a specific buyer at a specific chain thinks can decide a launch, proximity is the product.
Meet shoppers where they buy - the shelf, the cart, the product page - and treat that moment as a media channel worth planning, buying, and measuring.
The expertise is the moat
Commerce marketing is a specialist trade, and the specialists are not easy to find. It asks for people who can read a retailer's category strategy, negotiate the mechanics of a retail media network, build a piece of shoppable creative, and then model whether the whole thing moved units - often for the same client in the same quarter. Mars United's stated approach is to cross-train its staff across those functions rather than silo them, so a team can follow a brand from insight to shelf to measurement without handing off between agencies. The firm frames its culture around one shared line - make each client's business better today than it was yesterday - and around a habit of challenging the status quo rather than defending old playbooks.
Who hires them, and why
The client roster skews toward large consumer packaged goods manufacturers and Fortune 500 marketers - the companies whose products live on grocery, mass, drug, and club shelves and increasingly on marketplace search results. For these brands the hard problem is no longer awareness; it is winning the specific instant of purchase across a fragmenting set of retailers, each with its own media network, data, and rules. That is the problem Mars United Commerce is built to solve.
How it is different
Plenty of agencies now claim commerce as a capability; most bolted it on when retail media got hot. Mars United's argument is chronology and focus. It has done this one thing for more than 50 years, it built the technology to measure it in-house, and it kept its people near the retailers instead of near the ad-industry capitals. Its main rivals are the commerce practices inside the other holding companies - Publicis's own peers like Omnicom, with its Flywheel and Transact units, and WPP's commerce operations - along with a shrinking field of independent shopper and retail-media specialists.
We have best-in-class capabilities across the full spectrum of commerce marketing. Rob Rivenburgh, Global CEO
The competitive irony is that the thing making Mars United valuable - being the largest independent commerce shop - is exactly what ended its independence. Publicis had spent 2024 assembling a connected-commerce stack, and a self-contained, technology-equipped commerce specialist with a half-century of retail relationships was the missing piece.
The business, and the sale
The company runs on the familiar agency model: fees and retainers for strategy, media, content, and consultancy, with the Marilyn platform as the differentiator that keeps clients close. Estimated annual revenue sits near $97 million. Under the September 2024 acquisition, reported at roughly $600 million, Publicis kept the Mars United Commerce brand and its team intact and opened its capabilities to the wider network. Global CEO Rob Rivenburgh, a commerce veteran who spent more than two decades at the firm and helped build its retail consultancy network, continued to lead it.
Fifty years, briefly
Marilyn Barnett founds the agency, pioneering shopper marketing as a discipline.
Builds the industry's first field-based network of retail consultancy hubs near major retailers.
The Mars Agency rebrands as Mars United Commerce, unifying its full commerce offering.
The Marilyn platform expands with new commerce media, measurement, and retail media tools.
Publicis Groupe acquires the roughly 1,000-person firm in a reported $600 million deal.
Mars United Commerce showcases commerce-and-creativity work at Cannes Lions.
Where it fits now
Retail media is the fastest-growing corner of advertising, and the brands funding it need someone who understands both the media math and the retailer relationships behind it. That is the seat Mars United Commerce occupies - now as the commerce marketing engine inside Publicis rather than the largest independent alternative to it. The bet the firm made in 1973, that the moment of purchase deserved its own craft, turned out to be the part of marketing everyone else eventually came looking for.
Questions people ask
What does Mars United Commerce do?
It helps brands and retailers sell more across stores, retailer sites, and marketplaces through strategy, retail media, content, retail consultancy, and its Marilyn technology platform.
Who founded it, and when?
Marilyn Barnett founded the agency in 1973. It is widely credited as the first shopper marketing agency.
Why is the platform called Marilyn?
The proprietary commerce marketing technology platform is named after the company's founder, Marilyn Barnett.
Did Publicis acquire Mars United Commerce?
Yes. Publicis Groupe acquired it in September 2024 in a reported ~$600 million deal, keeping the brand and roughly 1,000-person team intact.
Where is it based?
It is headquartered in Southfield, Michigan, with around 14 hubs across North America, Europe, and Asia-Pacific.