SoftBank's boss, Masayoshi Son. Tomohiro Ohsumi/Getty ImagesOpenAI raised $6.6 billion in a deal that values the company at more than $150 billion.Investors include Nvidia, Thrive Capital, and an investment firm backed by the United Arab Emirates.Also among the backers are SoftBank, Tiger, and Ark, which have a record of investing at the top.OpenAI has officially closed a historic funding round.