After joining with Mr. Musk to create OpenAI in 2015 and pledging to carefully develop artificial intelligence for the benefit of humanity, the suit claimed, Mr. Altman and Mr. Brockman abandoned this mission by entering its multibillion-dollar partnership with Microsoft.

Elon Musk has filed an amended complaint against OpenAI, accusing the company — and its close partner, Microsoft — of anticompetitive dealings.

The lawsuit argues that OpenAI and Microsoft are “actively trying to eliminate competitors” by exchanging “competitively sensitive information,” and making their investors