Meta has rebuilt Andromeda, the system that decides which ads are considered for each person on Facebook and Instagram, because generative AI tools have helped advertisers create “hundreds of millions of new ads,” according to an October 28 post on the company’s Engineering at Meta blog written by 12 of its engineers.

Andromeda is the first stage of Meta’s ad delivery. It cuts the full pool of eligible ads down to a short list of candidates in milliseconds, and a slower ranking model then picks the ad that is shown. The engineers wrote that the AI-driven growth in ads pushed “Meta’s ads candidate pool to an unprecedented scale,” and that the new version “scores every eligible ad” while surfacing top candidates at more than one billion ads per second, which Meta says is 100 times the throughput of the 2024 system.

Meta gave one result for advertisers: Andromeda “has delivered a 2.4% increase in conversions on Facebook” since 2025. The post gives no figure for Instagram. Meta says advertisers get the gains “automatically,” with no setting to change.

Targeting Rules Now Act as a Filter

The post describes how the system splits the work. Advertisers’ targeting rules are still enforced, in a step Meta calls index matching, which removes ads a person is not eligible to see. Among the ads that remain, a model decides relevance. It draws on a person’s ad engagement history, cohort data and “LLM-derived semantic features,” and combines each ad’s content with the context of the moment it would be served. The model routes each ad to the most relevant of several sub-models that each represent a different set of a person’s interests.

Meta built the new version with Nvidia, which supplied optimized GPU code, and the engineers wrote that the system still has room to “absorb significantly more model complexity.” The post’s closing paragraph says the volume of eligible ads “continues to grow, driven by Advantage+ automation and generative AI creative tools.”

What Practitioners Have Been Telling Advertisers

Performance agencies have been describing the same mechanism from the outside. At Motion’s Creative Strategy Summit in June, Ignacio Manchi, senior director of media buying and creative insights at the agency Ready Set, said Andromeda narrows millions of ads to roughly a thousand candidates. “If you’re not on Andromeda’s short list for the action itself, you’re not in the game,” Manchi said, adding that budget, bidding, campaign structure and audience do not matter for an ad left off that list.

Manchi said that is why agencies began pushing for creative diversity, meaning ads aimed at different buyers, messages and emotions. “When Andromeda evaluates ads that are too similar to each other, it doesn’t run them at all because it clusters them as a single group,” Manchi said. Meta’s post does not mention clustering, so that account is Manchi’s reading of how the system behaves.

Andrew Foxwell, co-founder of the advisory firm Foxwell Digital, made a similar case to NI in September, saying audience containers on Meta are “less useful and less necessary than they used to be” because the system now matches ads to what each person has engaged with before.

The volume argument has limits. Of the 578,750 Meta ads launched between September 2025 and January 2026 in Motion’s 2026 Creative Benchmarks report, about 5% became winners, which Motion defines as ads that spent at least 10 times their account’s median ad and at least $500. Zach Stuck, co-founder of the direct-to-consumer brand Mars Men, told the same summit that Mars Men sets a fixed daily testing budget for each creative concept. “I would rather launch better ads with better concepts,” Stuck said, comparing that approach with “saying, hey, I need a thousand new ads.”

That demand for varied creative is part of why brands now buy creator content as ad supply. NI has covered companies built around it, from Street Poller Media turning street interviews into performance ads to Superfiliate’s CEO arguing that creators have taken over creative production.

Meta has not said how many ads it now evaluates per request, how the 2.4% conversion figure was measured, or whether Instagram advertisers have seen a comparable lift.

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