OpenAI has finalised a secondary share sale that values the company at US$500 billion, surpassing Elon Musk’s SpaceX to become the world’s most valuable startup.

In the deal, current and former employees sold about US$6.6 billion worth of stock to investors including Thrive Capital, SoftBank Group, Dragoneer Investment Group, Abu Dhabi’s MGX, and T. Rowe Price, Bloomberg reported citing a person familiar with the matter.

The new valuation marks a sharp jump from the US$300 billion level set during a SoftBank-led financing round earlier this year.

The surge highlights the intense investor appetite for companies at the forefront of artificial intelligence, a technology poised to reshape industries and economies worldwide.

Sam Altman’s OpenAI is among several firms, including Nvidia Corp., driving a global effort to build data centers and expand artificial intelligence services—an initiative projected to cost trillions of dollars.

The deal propels OpenAI past SpaceX’s US$400 billion valuation, arriving at a crucial moment as the company negotiates with Microsoft to transition into a more conventional for-profit structure.

Founded in 2015 as a nonprofit committed to advancing digital intelligence “in the way that is most likely to benefit humanity as a whole,” OpenAI plans to create a public benefit corporation under the control of its existing nonprofit entity.

Both Altman and Musk, who co-founded OpenAI, have previously warned about the existential risks AI could pose to humanity. However, the two have since fallen out.

OpenAI spokesperson declined to comment.