OpenAI has completed a deal to help employees sell shares in the company at a $500 billion valuation, propelling the ChatGPT owner past Elon Musk’s SpaceX to become the world’s largest startup.

Current and former OpenAI employees sold about $6.6 billion of stock to investors including Thrive Capital, SoftBank Group Corp., Dragoneer Investment Group, Abu Dhabi’s MGX and T. Rowe Price, a person familiar with the transaction said. That boosted the US company’s price tag well past its previous $300 billion level during a SoftBank-led financing round earlier this year.

That rapid rise underscores the investment frenzy surrounding the leaders of a technology with the potential to transform industries and economies. Sam Altman’s OpenAI is one of several companies including Nvidia Corp. now leading a global push to build data centers and develop artificial intelligence services, an undertaking that’s expected to cost trillions of dollars. Though it has yet to turn a profit, the US startup is helping fuel that infrastructure boom by inking mega-sized deals with the likes of Oracle Corp. and SK Hynix Inc.

Representatives for Thrive Capital and Dragoneer didn’t immediately respond to requests for comment. OpenAI, SoftBank and T. Rowe Price spokespeople declined to comment. A spokesperson for MGX said the firm is “pleased to be a core partner to OpenAI and to continue building on our strong relationship as a significant investor across multiple funding rounds.”