Thinking Machines Lab closes $5B funding at $40B valuation

Mira Murati's Thinking Machines Lab is closing a $5B round led by Accel at a $40B pre-money valuation, more than tripling its ~$12B mark from last year's $2B seed. Nvidia is separately in talks to invest ~$2.5B, with the round potentially closing this week. The company was founded last year by former OpenAI Chief Technology Officer Mira Murati.

Thinking Machines Lab is set to close a $5 billion funding round at a $40 billion pre-money valuation as soon as this week, with Accel leading the investment. The round represents a dramatic valuation acceleration for the AI startup founded by Mira Murati, who previously served as OpenAI's chief technology officer before launching Thinking Machines Lab in February 2025.

The round would more than triple the startup's valuation from its last public financing, when it raised a $2 billion seed round last year at a valuation above $10 billion before releasing a product. Nvidia is separately in talks to invest around $2.5B, indicating strong support from the chip manufacturer for the AI startup's growth trajectory.

The timing of the funding announcement coincides with Thinking Machines Lab's release of Inkling 2 Small, a Mixture-of-Experts architecture featuring 594 billion total parameters, with 17 billion parameters active during computation. According to the company, Inkling 2 Small doubled the model's forecasting score in 4.5 hours. The model ranked 1st among open-weights models on DesignArena.

From October 2025 to January 2026, three of Mira Murati's co-founders left for Meta and OpenAI, though the company appears to be maintaining strong momentum with its latest funding and product releases. If the round closes, Thinking Machines will have raised about $7 billion in disclosed funding.