Musk vs. OpenAI Trial Enters Final Phase as Microsoft CEO and Altman Set to Testify

TLDR

• Microsoft CEO Satya Nadella testifies Monday in Musk’s lawsuit against OpenAI
• Musk claims Altman and OpenAI deceived him by turning the nonprofit into a for-profit company
• Internal Microsoft emails from 2018 are central to Musk’s case against the tech giant
• OpenAI cofounder Ilya Sutskever and Sam Altman are also expected to take the stand
• An advisory jury will give its view on wrongdoing the week of May 18

Elon Musk’s lawsuit against Sam Altman and OpenAI is entering its final stretch, with several high-profile witnesses still to testify before closing arguments.

Microsoft CEO Satya Nadella took the stand on Monday, May 11, in a California federal court. His testimony is a key moment in the trial, which centers on whether OpenAI broke its founding promise to operate as a nonprofit focused on the public good.

Musk, who cofounded OpenAI, claims Altman and OpenAI president Greg Brockman deceived him as they moved the company toward a for-profit structure. OpenAI says Musk is simply trying to slow the company down while his own AI startup, xAI, tries to catch up.

Musk’s legal team is leaning on internal Microsoft emails from January 2018. In those emails, Nadella questioned the value of giving OpenAI cheaper access to Microsoft’s Azure cloud and said he could not tell what research the company was doing.

Shortly after those emails, OpenAI launched a for-profit arm to bring in outside investment. Microsoft then invested $1 billion in 2019. It has since committed $13 billion in total, and its stake is now valued at around $228 billion — roughly a 27% share of OpenAI’s for-profit unit.

Musk’s lawyers argue this timeline shows Microsoft knowingly helped pull OpenAI away from its nonprofit roots.

Microsoft’s Defense

Microsoft has pushed back ahead of Nadella’s testimony. Its lawyers argued the company did not and could not have helped breach a charitable trust.

They also pointed out that Musk had Nadella’s personal phone number but never raised concerns about the Microsoft-OpenAI partnership for five years. They also cited a 2020 post by Musk on X where he described OpenAI as “essentially captured by Microsoft,” arguing he knew about the commercial ties long before filing the lawsuit in 2024.

What Comes Next

After Nadella, OpenAI cofounder Ilya Sutskever is also expected to testify. Sutskever led the 2023 effort to remove Altman from the company, then quickly reversed course and backed his return. He later left OpenAI and has not spoken to Altman in over a year, according to a 2025 deposition.

Sam Altman himself is expected on the stand later this week. Questions about his trustworthiness are central to Musk’s case.

Because this is a civil trial, there is no “guilty” verdict. The jury decides if the defendants are liable and how Musk should be compensated. Judge Yvonne Gonzalez Rogers will make the final call on any remedies.

An advisory jury is expected to deliver its view on wrongdoing during the week of May 18.

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