Microsoft and OpenAI have reached a deal to allow the ChatGPT maker to restructure itself into a public-benefit corporation, valuing OpenAI at $500bn and giving it more freedom in its business operations. The deal, unveiled on Tuesday, removes a major constraint on raising capital for OpenAI that has existed since 2019. As its ChatGPT service exploded in popularity, those limitations had become a notable source of tension between the two companies. Microsoft will still hold a stake of about $135bn, or 27 percent, in OpenAI Group PBC, which will be controlled by the OpenAI Foundation, a nonprofit, the companies said. Microsoft, based in Redmond, Washington in the United States, has invested $13.8bn in OpenAI, with Tuesday's deal implying that the firm had generated a return of nearly 10 times its investment.