Thinking Machines Lab co-founder Andrew Tulloch is leaving the startup for Meta, according to a Wall Street Journal report. Tulloch announced his departure to employees in a message on Friday, and a Thinking Machines spokesperson confirmed the move, saying he “has decided to pursue a different path for personal reasons.”

The exit comes days after Thinking Machines, led by former OpenAI CTO Mira Murati, launched its first product, Tinker, a training API for fine-tuning open-weight models. It also follows a reported attempt by Meta to acquire the lab in August. When that bid failed, the Journal reported, Meta tried to lure Tulloch with a package that could have been worth up to $1.5 billion over at least six years. At the time, a Meta spokesperson called that description “inaccurate and ridiculous.”

Tulloch previously spent 11 years at Meta and then worked at OpenAI before co-founding Thinking Machines earlier this year.

The news comes days after Thinking Machines debuted Tinker, its first product, and months after the company’s $2 billion seed round.