OpenAI asks investors not to back rival start-ups such as Elon Musk’s xAI Financial TimesOpenAI closes funding at $157 billion valuation, as Microsoft, Nvidia, SoftBank join round CNBCOpenAI just closed a megaround. Here's how its funding stacks up to other Bay Area AI startups The Business JournalsOpenAI gets $6.6 billion in new funding, valuing company at $157 billion The Washington Post