OpenAI has raised 6.6bn ( 5bn) in a funding round that values the artificial intelligence business at 157bn, with chipmaker Nvidia and Japanese group SoftBank among its investors. The San Francisco-based startup, responsible for the ChatGPT chatbot, did not give details of a reported restructuring that will transform it into a for-profit business. The funding round was led by Thrive Capital, a US venture capital fund, and other backers include MGX, an Abu Dhabi-backed investment firm. OpenAI's post-fundraising valuation puts it on a par with Uber, although it remains far below the 3tn level of its biggest backer of recent years, Microsoft, which also joined the fundraising. Other investors included Nvidia, a dominant player in the market for the chips that train and operate AI models, and Softbank, which counts the UK chip designer Arm among its investments.