Circular financing adds a big new risk.Nvidia's (NVDA 0.27%) announcement that it will invest up to $100 billion in OpenAI is being hailed by the company as a massive bet on the future of artificial intelligence (AI). Still, investors should take a closer look at what is really going on here. The money OpenAI receives will ultimately be plowed right back into Nvidia hardware, mostly through Oracle's cloud buildout, where the two companies recently signed a massive $300 billion deal. OpenAI plans to deploy N ...