Excluding Amazon, the global retail advertising market is forecast to grow just 9.8% in 2027, marking the lowest year-over-year growth rate since WARC Media began tracking the category, according to Insideradio. The 9.8% growth exposes a market where impressive top-line growth conceals a profound struggle for diversified expansion.

The global retail media market is projected to surpass $200 billion in 2026, yet its growth rate, excluding Amazon, is set to dip to a record low of 9.8% in 2027. The dip to a record low of 9.8% in 2027 marks a critical divergence: the market's overall expansion is almost entirely propped up by a single dominant player.

Companies increasingly rely on Amazon for retail media reach, stifling competition and limiting diversified ad spend across other platforms. The concentration of power transforms a burgeoning market into a winner-take-all landscape, where only Amazon truly thrives.

The Expanding Retail Media Pie

The global retail media market is projected to reach $200.4 billion in 2026 and $223.4 billion in 2027, an 11.5% increase from 2026, according to Insideradio. The projected market size of $223.4 billion in 2027 positions retail media to account for 15.2% of all advertising investment worldwide by 2027. While these figures suggest robust expansion, they obscure a fundamental truth: the market's rapid growth is not evenly distributed. The collective investment reaching $223.4 billion by 2027 has undeniable significance for brands seeking direct consumer engagement, yet the broad growth distorts the actual market health for most participants, masking a deeper competitive imbalance.

Amazon's Unmatched Market Share

Amazon commanded 78% of U.S. retail media spending in 2025, while Walmart captured a mere 7.5%, according to Insideradio and Roastbrief US. Amazon's 78% share leaves rivals with a fraction of the market, revealing a profound competitive imbalance. Other retailers are not merely struggling; they are being systematically marginalized into niche roles. The disparity extends to absolute spending: emarketer data shows Amazon's US retail media ad spending at $56.71 billion in 2026, dwarfing Walmart's $5.99 billion. This means other retailers are not just competing for ad dollars; they are fighting for scraps in a market overwhelmingly dominated by a single player, severely limiting brands' opportunities for diversified advertising channels.