Thinking Machines Lab: Mira Murati's AI Startup Hits $12 Billion Valuation in Largest Seed Round in Silicon Valley History

When Mira Murati, the former Chief Technology Officer of OpenAI, left the company in late 2024 and launched Thinking Machines Lab in February 2025, the AI industry paid close attention. What followed validated that attention in a way that exceeded almost every prediction about how quickly a new AI lab founded by a credible team could raise money and reach scale.

In July 2025, Thinking Machines Lab officially closed a $2 billion seed round led by Andreessen Horowitz, at a $12 billion post‑money valuation. This was, by most measures, the largest seed round in the history of Silicon Valley technology and one of the most significant early‑stage AI financings ever recorded. It came less than six months after the company's founding, at a point when it had no publicly released products and no disclosed revenue. The round was joined by Nvidia, Accel, ServiceNow, Cisco, AMD, and Jane Street, a mix of strategic technology investors and financial institutions that reflected the breadth of belief in what Murati and her team were building.

The company's founding team was itself a significant signal to investors. Murati assembled a core group that included former OpenAI co‑founder and chief scientist John Schulman, former VP of Research Barret Zoph, former VP Lilian Weng, and a broader group of approximately 30 researchers and engineers drawn from OpenAI, Meta AI, Mistral, and other leading AI labs. The density of frontier AI research experience in a single founding team was genuinely unusual, and the seed round reflected investors' assessment of what that team was capable of building.

Thinking Machines Lab's mission, as stated publicly by Murati, is to build multimodal AI that works with how people naturally interact with the world: through conversation, sight, and the messy reality of how humans actually collaborate. The company is structured as a public benefit corporation, and Murati holds a deciding vote on board matters, structured to give her majority decision‑making capability. The Albania government, Murati's country of origin, also participated in the seed round with a $10 million investment.

The company released its first product in October 2025: Tinker, an API designed to help developers and researchers fine‑tune large language models with significantly less complexity and cost than traditional fine‑tuning workflows require. Where most AI labs focus on building bigger models that require more data and more compute, Thinking Machines Lab positioned itself with a different bet: building smarter, more customizable models using efficient post‑training techniques. Tinker was built for the researchers, startups, and technical teams who want control over how AI models behave in their specific domains without needing to rebuild from scratch.

The company's trajectory since its seed round has continued to attract attention. By March 2026, Thinking Machines Lab announced a strategic partnership with Nvidia involving an undisclosed investment and a multi‑year agreement to deploy one gigawatt of Vera Rubin computing capacity, a deal that signals both Nvidia's confidence in the lab and the scale of compute Murati's team is now accessing to train next‑generation systems. The company was also reportedly in early talks as of late 2025 to raise a new round at a valuation approaching $50 billion, which would represent more than a fourfold increase from the seed valuation in less than a year.

There have been some internal transitions along the way. Barret Zoph and Luke Metz, both founding team members, departed the startup in January 2026 to return to OpenAI, a reminder that competition for top AI research talent remains intense across the entire industry. However, other prominent researchers have joined, including Soumith Chintala, the co‑creator of the PyTorch open‑source AI framework, who left Meta to join Thinking Machines Lab in late 2025.

Key facts about Thinking Machines Lab as of early 2026:

• Founded: February 2025 by Mira Murati and co‑founders from OpenAI
• Seed round: $2 billion at $12 billion valuation, led by Andreessen Horowitz
• Key investors: Nvidia, Accel, ServiceNow, Cisco, AMD, Jane Street, Albania government
• First product: Tinker, an API for efficient large language model fine‑tuning, released October 2025
• Infrastructure: Multi‑year Nvidia Vera Rubin deal announced March 2026, 1GW compute deployment
• Structure: Public benefit corporation, Murati holds board majority vote
• Reported next round: Talks at approximately $50 billion valuation, as of late 2025 reporting

Thinking Machines Lab represents one of the most ambitious and most watched new AI labs of the current generation. Whether it can develop the frontier model capabilities needed to compete with OpenAI, Anthropic, and Google DeepMind remains the defining question, but the $12 billion seed valuation and the Nvidia infrastructure deal signal that the company has both the capital and the compute to pursue that ambition.

Official Sources: Thinking Machines Lab