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.

Not an ad company, but its privacy rules on iPhone reshaped mobile advertising, and it sells App Store ads.

China's leading search engine, whose ad business is shifting to AI-powered search and the Ernie models.

The largest ad business on earth: search ads, YouTube, and tools on both sides of the open-web ad market.

Microsoft's professional network, the default ad channel for business-to-business marketers.

Owner of Facebook, Instagram, WhatsApp and Threads, and the second-largest digital ad seller worldwide.

Search ads on Bing and Copilot, plus ads across Microsoft properties, Xbox and partner sites.

South Korea's dominant search portal, selling search, display and shopping ads.

The biggest streaming service, which added a cheaper ad-supported plan in 2022 and now runs its own ad tech.

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

Community forum network selling ads targeted by topic and conversation, and licensing data to AI firms.

TV operating system and streaming devices that make money selling ads on the home screen and in apps.

Maker of Snapchat, selling ads between Stories, in Spotlight and through AR lenses.

The largest audio streaming service, selling audio, video and podcast ads to free listeners.

Owner of WeChat and QQ, and one of the biggest ad sellers in China through its apps and games.

Short-video giant whose ad business rivals Meta and YouTube for younger audiences.

The social network formerly called Twitter, now part of the Musk group of companies via xAI and SpaceX.

Web pioneer, now private-equity owned, running news, finance and sports sites plus a DSP.

Russia's largest search engine and ad platform, now a Russian-owned company listed in Moscow.