OpenAI is in early discussions to conduct a secondary share sale that would value the artificial-intelligence company at roughly $500 billion, according to people familiar with the talks. The transaction would give current and former employees an opportunity to cash out part of their holdings, while new and existing investors buy the stock on the secondary market. A sale at that price would mark a sharp rise from the $300 billion valuation OpenAI commanded in March and would eclipse the private-market worth of any other technology start-up. Investors including Thrive Capital have approached the San Francisco-based firm about purchasing shares, the people said. The size of the offering could reach several billion dollars, though terms have not been finalized. If completed, the deal would underscore the surging demand for companies developing generative-AI tools such as ChatGPT and cement OpenAI’s position as the world’s most valuable privately held tech company. A representative for OpenAI declined to comment.