Thinking Machines Lab, the AI startup founded by former OpenAI CTO Mira Murati, is raising $5 billion at a $40 billion pre-money valuation, according to Business Insider sources. The raise follows a $2 billion seed round completed last year at over $10 billion valuation, after a previous attempt targeting $50 billion collapsed due to broken negotiations. Concurrently, Thinking Machines Lab unveiled Inkling 2 Small, its second-generation model featuring a Mixture-of-Experts architecture with 594B-A17B parameters. The model underwent four pretraining stages and nine days of joint reinforcement training, achieving significantly higher analytical intelligence scores than predecessors in coding, vision, knowledge work, and reasoning. Inkling 2 Small will be released with open weights under Apache 2.0 license next week.