The Hidden War Behind Amazon vs Walmart's Sales Battle
How Two Ad Giants Are Fighting for the Future of Retail Marketing
When Amazon and Walmart scheduled their biggest sales events for overlapping dates in July 2024 — Prime Day (July 8-11) and Walmart Deals (July 8-13) — it looked like a simple pricing war. But after major agency partnership changes in late 2024, we can see a preview of how different marketing philosophies will shape retail competition.
The timing reveals something fascinating: while these retail giants were battling in July, they were also quietly conducting major agency reviews that would fundamentally change their marketing approaches for 2025 and beyond.
The Agency Shake-Up That Followed
Walmart's Established Partnership with Publicis
Walmart had already made its strategic bet back in August 2021, consolidating its $600 million US media business with Publicis Groupe after what executives called "an incredibly competitive RFP process" (Walmart, 2021). The partnership replaced WPP's Haworth, which had held the account for five years.
William White, Walmart's Senior VP and Chief Marketing Officer, explained the choice: "We are impressed with their people, their marketing thought leadership and their expertise in full-funnel planning, execution and measurement capabilities" (Chain Store Age, 2022).
This wasn't just about media buying. Publicis had already been handling Walmart's creative work since 2016 through a bespoke unit called Po1, making this a full integration of creative and media capabilities.
Amazon's Major Account Split
While Walmart's agency strategy was settled, Amazon was conducting what industry insiders called "the biggest pitch the industry has ever encountered." In September 2024 — two months after the July sales battle — Amazon concluded its massive global media review.
The result surprised many: instead of choosing one agency, Amazon split its estimated $5 billion global account between two holding companies. Omnicom Media Group won the Americas business, while WPP's GroupM secured EMEA and APAC regions (Adweek, September 2024).
Amazon spokesperson Margaret Callahan explained: "After a comprehensive advertising agency review for our consumer business, we've chosen to partner with OMG and WPP... This decision was made after a careful and extensive review process."
IPG Mediabrands, which had held the account for over a decade since 2013, retained Amazon Web Services, Amazon Business, and Amazon Ads.
What This Reveals About Retail Marketing Philosophy
Walmart's Integrated Omnichannel Approach
Under Publicis's guidance since 2021, Walmart has transformed its marketing to connect online and in-store experiences seamlessly. The July 2024 Walmart Deals event was the first time online promotions fully integrated with in-store experiences — shoppers could find the same deals whether browsing the app or walking through physical stores.
This reflects what Arthur Sadoun, Publicis CEO, calls "breaking down silos" between different marketing functions. For Walmart's 4,600 US stores, this means physical locations become extensions of digital marketing campaigns rather than separate channels.
Key elements of Walmart's approach:
Unified customer experiences across 10,500 global stores and digital properties
Marketing messages that flow seamlessly between mobile apps, in-store displays, and checkout
Integration of shopping data from both online browsing and in-store purchases
Amazon's Precision-Focused Strategy
Amazon's approach, now split between Omnicom (Americas) and WPP (globally), emphasizes data-driven precision and algorithmic optimization. With $56 billion in global advertising revenue, Amazon can target and optimize at a scale that few companies can match.
The decision to extend Prime Day from the traditional two days to four days in 2024 likely reflected this data-driven approach — testing different duration scenarios to optimize both merchant satisfaction and customer engagement.
Amazon's strategy strengths:
Algorithmic sophistication across millions of products and customers
Real-time optimization based on competitor pricing and inventory levels
Predictive modeling that anticipates customer needs
The Broader Industry Impact
Agency Consolidation Trends
Both partnerships reflect a broader industry trend toward specialized retail media capabilities. As retail advertising becomes more complex — requiring deep platform knowledge, first-party data integration, and omnichannel coordination — brands increasingly value specialized expertise over general advertising services.
The 2024 agency performance numbers show this shift:
Omnicom Media Group: $7.7 billion in new business with 74% client retention rate
Publicis Media: $6.5 billion in new business, leading in net growth with $5.8 billion in incremental billings
Technology Integration as Competitive Advantage
Both holding companies have made massive technology investments specifically for retail media:
Publicis: Acquired Epsilon for $4.4 billion to enhance customer data capabilities
Omnicom: Developed the Omni platform for cross-platform optimization and attribution
These technology stacks create defensive advantages. Once a retailer's systems integrate deeply with an agency's tools, switching becomes increasingly complex and disruptive.
Looking Forward: What 2025 Holds
Different Approaches to Consumer Challenges
Both retailers face the same fundamental challenge: consumer attention is becoming scarce and expensive. Recent data shows 31% of people now ignore social media ads, with engagement rates collapsing across platforms.
Prime Day and Walmart Deals represent responses to this attention crisis. Rather than competing for consumer attention in crowded social feeds, both retailers create exclusive time periods when customer attention is guaranteed and focused.
However, their solutions reflect different philosophies:
Walmart (via Publicis): Create lifestyle-driven product collections and integrated experiences
Amazon (via Omnicom/WPP): Use algorithmic recommendations and data-driven personalization
The Platform Competition Expands
As more retailers like Target, Best Buy, and Home Depot build significant advertising businesses, agency holding companies must choose where to concentrate their retail media expertise.
The Walmart-Publicis and Amazon-Omnicom/WPP partnerships likely represent templates that will be replicated across other major retailers, creating ecosystems of agencies specialized around specific retail platforms.
The Real Battle Ahead
The July 2024 sales events were just the beginning. With their agency partnerships now firmly established, both retailers are positioned to test fundamentally different theories of retail marketing:
Walmart's integrated approach may prove superior for brands seeking comprehensive customer journey management across physical and digital touchpoints.
Amazon's precision-driven methodology might deliver better performance for conversion-focused campaigns and real-time optimization.
The ultimate winners won't be determined by sales figures from any single event, but by which retailer-agency partnership creates more sustainable competitive advantages in the evolving retail media landscape.
Both Publicis and Omnicom are betting billions on fundamentally different theories of how marketing technology, consumer behavior, and retail commerce intersect. The July 2024 sales events were just the opening moves in a much larger game—one where agency capabilities increasingly determine retail success.
As we head into 2025, these partnerships will face their real test: can they adapt to changing consumer behaviors, platform algorithm updates, and the ongoing attention economy crisis while delivering measurable business results for their retail partners?