Elon Musk’s lawsuit over OpenAI’s shift to a for-profit model kicks off in Oakland, with Musk, Sam Altman and Microsoft’s Satya Nadella set to testify. The case highlights internal clashes as OpenAI faces fierce AI competition and gears up for a potential $1 trillion IPO.

• Musk's lawsuit against Altman and OpenAI's board over its shift to a for-profit model goes to trial in Oakland, with Musk, Altman, and Satya Nadella testifying.
• OpenAI's lawyers will argue Shivon Zilis, ex-board member and mother of four of Musk's children, leaked sensitive inside information to Musk.
• Musk claims the for-profit restructuring betrayed the nonprofit's mission and diluted early backers' control; Altman argues it was necessary to fund massive compute costs.
• The trial unfolds as OpenAI competes with rivals like Anthropic and prepares for a possible IPO valuing it near $1 trillion.