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# OpenAI details ChatGPT’s ad stack: a custom LLM orchestrator
- URL: https://www.medianexis.com/openai-details-chatgpts-ad-stack-a-custom-llm-orchestrator/
- Published: 2026-10-22T16:05:00.000Z
- Updated: 2026-10-22T16:05:00.000Z
- Description: OpenAI is explaining that ChatGPT’s ad system runs on a custom post-trained LLM “orchestrator” that calls tools for retrieval, ranking, relevance and auctions across stateful, multi-turn sessions, kept in a separate service from answer generation.
- Author: The Signals Desk
- Tags: Ad-tech, AI, OpenAI details how it built ChatGPT's ad stack

**Why it matters.** Advertisers gain a new agentic ad-buying surface where eligibility depends on an LLM’s judgment of conversational intent rather than discrete keyword queries.

*Signal from* [*openai.com*](https://openai.com/?ref=medianexis.com) *·* [*read the original*](https://openai.com/index/building-chatgpt-ad-stack/?ref=medianexis.com)*.*