Square Peg Capital is an investor in one of the largest and most competitive seed funding rounds in Silicon Valley history: a $3 billion raising for Mira Murati’s secretive artificial intelligence start-up, Thinking Machines Lab.

Murati is one of the highest-profile figures in San Francisco’s big-money AI scene, and briefly replaced Sam Altman as chief executive of OpenAI when he was sacked in late 2023. She resigned as OpenAI’s chief technology officer last October, and has since had investors scrambling to buy into her new company, which is valued at $US12 billion ($18.4 billion) after the deal.