Shivon Zilis, former director of OpenAI Inc., arrives in federal court in Oakland, California, on Wednesday, May 6, 2026.
David Paul Morris | Bloomberg | Getty Images
Elon Musk’s high-stakes lawsuit against OpenAI CEO Sam Altman concludes its second week of proceedings on Thursday.
Musk’s lawyers called multiple witnesses to the stand this week, including OpenAI president Greg Brockman and Siobhan Gillis, who serves on the startup’s board and has close personal and professional ties to Musk. Mr. Altman and microsoft CEO Satya Nadella may still be called to testify.
Gillis, who has four children with Musk, took the stand Wednesday and was questioned by Musk and OpenAI’s lawyers about conversations she had about OpenAI’s corporate structure around 2017 and 2018.
In 2024, Musk sued OpenAI, Altman, and Brockman, alleging that they reneged on promises to make the artificial intelligence companies nonprofit and conduct philanthropic work. He co-founded the startup in 2015 with Altman and Brockman.
OpenAI created a for-profit subsidiary after Musk left the company in 2018, and that business unit is at the center of Musk’s lawsuit.
Gillis said in his testimony that his primary role at OpenAI was to serve as a liaison between Musk, Altman, Brockman and the company’s other co-founder, Ilya Sutskeva.
Mr. Gillis testified that the four executives discussed OpenAI’s corporate structure, which includes several different commercial options, “addictingly.” At one point during the negotiations, Gillis said Musk wanted OpenAI to participate. teslaAnd he offered Altman a seat on the company’s board.
“There was so much discussion about all the possible structures that were put in place at the time,” Gillis said.
Elon Musk stands in an elevator on April 30, 2026, at a federal courthouse in Oakland, California, to attend a trial in a lawsuit over the commercial use of OpenAI.
Manuel Orbegoso | Reuters
Testifying earlier in the trial, Musk said he wasn’t entirely opposed to OpenAI’s commercial arm, but that it had become “a bit like wagging the tail at the dog.” He repeatedly accused Mr. Altman and Mr. Brockman of “trying to steal charity.”
Tesla’s CEO also discussed creating an AI lab within his electric car company that would compete directly with OpenAI, but that never happened, Gillis testified.
In 2023, Musk launched a competing AI company, xAI, which he merged with his rocket company SpaceX earlier this year.
Gillis, who has worked at several of Musk’s companies including OpenAI, said: tesla and his brain technology startup Neuralink started working for OpenAI as an unofficial advisor in 2016, which is how they met, he said.
She served on OpenAI’s board from 2020 to 2023, after Musk had already left the company. The couple had several children during this period, but Gillis testified that Musk’s involvement was initially kept secret.
He said they agreed to “complete confidentiality” in part to protect their children from potential safety risks associated with interacting with Musk. She said she ultimately had to tell Altman that Musk was the father when she learned that Altman’s involvement was revealed in the press.
OpenAI allowed Gillis to remain on its board, but said he ultimately resigned in 2023 when Musk decided to form xAI.
CNBC’s Lora Kolodny contributed to this article.
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