The players

China's e-commerce giant, whose Alimama unit runs one of the world's largest retail media businesses.

Amazon's ad arm: sponsored listings on the store, Prime Video ads, Twitch, and a DSP for the open web.

Amazon's demand-side platform, buying Prime Video, Amazon and open-web ads with shopping data.

Runs cashback offers inside banking apps, using card purchase data to target and measure.

South Korea's dominant online retailer, with a growing retail media business.

Commerce advertising company famous for retargeting, now centred on retail media for big retailers.

Criteo's platform powering sponsored-product ads for retailers' own websites.

Retail media network of Flipkart, India's biggest e-commerce marketplace, majority owned by Walmart.

Cashback rewards company whose Ibotta Performance Network puts offers inside retailers' apps.

Grocery delivery app with one of the largest retail media businesses, also powering ads for grocers.

API-based ad-serving infrastructure that retailers use to build their own retail media networks.

Retail media arm of MercadoLibre, Latin America's largest e-commerce and fintech company.

Machine-learning mobile DSP for app marketers, also powering retail media for commerce platforms.

Software for brands managing ads across Amazon, Walmart, Instacart and other retail media networks.

Visual discovery platform where people plan purchases, selling shopping-focused ads.

Japanese e-commerce, fintech and mobile group, owner of Rakuten Advertising and Rakuten Rewards.

Omnichannel marketing platform (formerly Kenshoo) for retail media, search and social.

Ads in the Uber and Uber Eats apps, in cars and on car-top screens.

Walmart's retail media network, selling ads on Walmart.com, in stores and across the web.