OpenAI confidentially files for initial public offering on US stock market

OpenAI has filed confidentially for an initial public offering, the company said Monday, setting the stage for one of the most highly valued stock market debuts in history with an expected valuation exceeding $850bn [1]. The artificial intelligence developer submitted an S-1 investor prospectus to the US Securities and Exchange Commission, a preliminary step that allows regulators to review financial disclosures before they become public [1]. “We recently submitted a confidential S-1. We expect it to leak so we’re just announcing it,” the company stated in a blogpost, adding that no timing has been set for the offering [1]. The filing follows a $122bn funding round in March that valued OpenAI at roughly $852bn, according to the Wall Street Journal [1]. The company was founded as a nonprofit research lab in 2015 and released ChatGPT publicly in November 2022, a launch credited with catalyzing the current AI boom [2]. A 2025 restructuring converted its for-profit subsidiary into a public benefit corporation that is 26% owned by the original nonprofit [2]. OpenAI’s path to the public markets has been marked by legal friction. A jury recently ruled against Elon Musk’s lawsuit seeking to force the company to revert to nonprofit status, finding the claims fell outside the statute of limitations [1]. The company also faces more than a dozen lawsuits alleging ChatGPT exacerbated mental health crises, with plaintiffs claiming the chatbot acted as a “suicide coach” and provoked violent acts [1]. The IPO arrives amid a wave of AI company listings. Rival Anthropic announced its own public filing last week, and Elon Musk’s SpaceX, which owns xAI, is expected to go public at a valuation of $1.75tn [1]. OpenAI has pursued expansion beyond text generation, acquiring designer Jony Ive’s startup in early 2025 and launching the Sora video generation app in late 2024, though Sora was shuttered in April 2026 [1]. Microsoft has invested over $13bn in OpenAI and provides Azure cloud computing resources [2]. The company’s Microsoft Copilot chatbot, launched in 2023, is built upon OpenAI’s GPT large language models and was introduced as a replacement for the discontinued Cortana assistant [11]. OpenAI has also secured partnerships with Google and Nvidia [1]. In October 2025, OpenAI conducted a $6.6bn share sale that valued the company at $500bn [2]. Throughout 2024, roughly half of the company’s then-employed AI safety researchers left, citing a deprioritization of safety goals [2]. The company has also faced multiple copyright infringement lawsuits from authors and media organizations whose work was used to train its models [2].