OpenAI could now be the world’s most valuable startup, ahead of Elon Musk’s SpaceX and TikTok’s parent company ByteDance, after a secondary stock sale designed to retain employees at the ChatGPT maker. The valuation reflects high expectations for the future of AI technology and continues OpenAI’s remarkable trajectory from its start as a nonprofit research lab in 2015. The stock sale is a first for OpenAI, which has been struggling to offer investors and staff the same perks and compensation as other companies. Facebook parent Meta Platforms, in particular, has been on a hiring spree for elite AI engineers and in June made a $14.3 billion investment in AI company Scale that recruited its CEO Alexandr Wang. OpenAI’s for-profit subsidiary, valued at $500 billion, is technically controlled by the board of OpenAI’s nonprofit and both are still bound to pursue the nonprofit’s charitable purpose.