ChatGPT creator OpenAI became the third major artificial intelligence developer to confidentially file for a public listing Monday, joining rivals in an IPO pipeline now worth some $3.6 trillion.SpaceX, which is officially known as Space Exploration Technologies Corp, is preparing for an IPO that would value the company at about $1.8 trillion. Anthropic raised funds at a $965 billion valuation last month. And OpenAI was worth $852 billion based on its most recent funding round in March.The Sam Altman-led firm submitted paperwork for an initial public offering with the US Securities and Exchange Commission, the company said Monday. OpenAI is working with Goldman Sachs Group Inc and Morgan Stanley on a potential listing as soon as the fall, people familiar with the matter have said.Deliberations are ongoing and details of the IPO plan could change. “We have not decided on timing yet; it may be a while because there are things we want to do that are likely easier as a private company,” OpenAI said. “But it’s a complicated set of tradeoffs and this gives us the option to go public sooner if that ends up being best.”