Billionaire Elon Musk is suing artificial intelligence (AI) titan OpenAI for an alleged breach of contract, arguing that the company abandoned its mission to “benefit humanity” and instead chose to become a “de facto” Microsoft subsidiary.

OpenAI is the maker of ChatGPT and a partner of Microsoft, which has backed it with billions of dollars. OpenAI is striving to increase revenue for Microsoft instead of helping humans, as originally intended, Musk alleged in the lawsuit filed in San Francisco, which also lists CEO Sam Altman and President Greg Brockman as defendants.