The company that once warned artificial intelligence could end civilisation now needs you to look at a Criteo-served banner ad.

OpenAI confirmed to Reuters on March 21 that it will begin showing advertisements to all users of ChatGPT’s free and Go tiers in the United States “in the coming weeks.” The ad-tech backbone comes from Criteo, the French targeting firm, which has been pitching advertisers on commitments between $50,000 and $100,000, according to The Information.

Three of the world’s largest ad agencies — WPP, Omnicom, and Dentsu — are part of the pilot programme. Some brands dedicated between $200,000 and $250,000 to the test, roughly double the typical experimental buy, according to CNBC. Several sources told CNBC they are frustrated by a conservative rollout that may leave those budgets unspent by quarter’s end.

Scale Is Coming Fast

The pace is picking up. Data from Sensor Tower shows ads served in the first half of March increased roughly 600% from the start of the month, reaching an estimated 5% of ChatGPT’s mobile user base. Truist analysts called 2026 an “inflection year” for LLM-powered advertising and projected OpenAI could generate under $1 billion in ad revenue this year — growing to over $30 billion by 2030.

Not everyone is following the same playbook. Anthropic ran a Super Bowl ad last month explicitly criticising OpenAI’s pivot and pledging its own platform would stay ad-free. Perplexity pulled ads from its platform after testing them in 2024.

OpenAI framed the rollout as deliberate. “We’re in the early testing phase of ads in ChatGPT, and the goal right now is to learn and refine the experience for consumers before expanding it more broadly,” the company told CNBC.

The refinement, one suspects, will be brief. Rising compute costs and a generative-AI arms race demand revenue that subscriptions alone cannot cover. The trajectory from research lab to ad network is not new in Silicon Valley. It is just faster this time.

Sources