SAN FRANCISCO, June 12 -- Jeff Bezos has found the one thing $12 billion still buys quietly. Prometheus, the physical-AI company he co-founded and now co-runs, emerged from stealth on Thursday by disclosing a $12 billion raise at a $41 billion valuation, TechCrunch reported, with the money coming from Bezos himself alongside JPMorgan Chase, Goldman Sachs and BlackRock. It is the second nine-figure-plus round for a 150-person company barely a year old.

What the money is meant to build is the part worth slowing down for. Prometheus calls its goal an artificial general engineer, software that designs and manufactures complex physical systems, the company's examples running from jet engines to drug compounds. Where OpenAI and Anthropic train...