The news: The connected TV (CTV) market is in flux as retail giants Amazon and Walmart escalate their fight for dominance—staking claims not just on content or devices, but on the operating systems themselves. 

Roku still leads with 34% CTV market share, per Omdia, but Walmart’s shift to Vizio’s SmartCast OS and Amazon’s strategic ad partnerships reveal intensifying competition over shoppable media and advertising dominance.

Their emerging duopoly is redefining how viewers shop, stream, and spend.

Retail giants square off on CTV: Walmart will stop licensing Roku’s OS for its Onn TVs and will now use Vizio SmartCast to better enable a future where shoppers buy directly from smart TVs. Walmart bought Vizio for $2.3 billion in 2024.

Meanwhile, Amazon and Roku joined forces, giving advertisers access to 80 million logged-in households via Amazon’s Demand Side Platform (DSP) and, by extension, 80% of US CTV households.

What this means for Walmart: The retailer is no longer dependent on third parties for CTV consumer access. It owns the hardware (Onn TVs) as well as the OS (Vizio), which are managed by its Walmart Connect ad network. 

This enables it to combine first-party purchase data with CTV ads, resulting in highly targeted campaigns.

What this means for Amazon: With Amazon DSP linked to Fire TV, Roku, Disney+, and Hulu, Amazon has up to 40% more unique reach and 30% less repetition for a larger pool of targeted ads, per Hollywood Insider. 

Our take: Amazon and Walmart are racing to close the gap between attention and action. Controlling TV hardware and CTV operating systems while linking them to first-party retail data helps build seamless, closed-loop ad ecosystems where viewers can become buyers in a click.

To stay competitive, marketers must optimize for closed-loop attribution, prioritize retail media integrations, and treat smart TVs as both screen and storefront as retail media and CTV ad spending surge.