Musk adds Microsoft as defendant in OpenAI legal war

Elon Musk's legal war against OpenAI just escalated into a multi-front antitrust battle.

In a 107-page amended complaint filed in Oakland federal court, Musk officially added Microsoft as a defendant. The filing also targets LinkedIn co-founder Reid Hoffman, former OpenAI board observer and Microsoft executive Dee Templeton, and California Attorney General Rob Bonta.

Musk didn’t come alone, either. His AI startup xAI and former OpenAI board member Shivon Zilis have now joined the lawsuit as plaintiffs.

Alleging a monopoly and boardroom collusion

The revised lawsuit shifts heavily from personal grievances into cutthroat antitrust accusations. Musk's team claims OpenAI controls roughly 70% of the generative AI market, alleging it functions as an illegal monopoly actively suppressing competitors.

According to the complaint, OpenAI extracted pledges from venture investors promising not to fund rivals like xAI. Musk also argues that OpenAI and Microsoft engaged in a de facto merger, granting OpenAI sweetheart compute rates and exclusive access to sensitive competitive data while locking rivals out.

The suit also targets boardroom entanglements. Hoffman's former roles spanning OpenAI's board, Microsoft's board, and venture firm Greylock allegedly granted him illicit market access, pointing to Greylock's investment in Inflection before Microsoft acqui-hired the team. Templeton's brief stint as a Microsoft-appointed observer at OpenAI is similarly framed as an illegal interlocking directorate.

The 2018 crypto plan that never happened

Tucked away inside the 107-page filing is a bizarre historical tidbit from early 2018, before OpenAI transitioned to a capped-profit model.

An email exhibit reveals Sam Altman pitching an Initial Coin Offering to fund OpenAI's research. Altman noted safety concerns from team members but suggested floating the token concept internally under strict confidentiality.

Musk immediately killed the idea. In an email back to Altman, Greg Brockman, and Ilya Sutskever, Musk wrote that an ICO would cause a massive loss of credibility for the company and everyone associated with it.

OpenAI, for its part, continues to brush off Musk's aggressive legal maneuvers, describing the lawsuit as blusterous and baseless while seeking dismissal.

Why it matters

This is no longer just Musk complaining about a broken promise to humanity. By adding xAI as a plaintiff and targeting Microsoft, Musk has turned a philosophical grudge match into a strategic corporate offensive.

We think the real target here is OpenAI’s upcoming restructuring into a fully for-profit public benefit corporation. By naming California AG Rob Bonta as a defendant just as OpenAI is negotiating that very transition, Musk is attempting to throw legal sand in the gears of OpenAI's corporate overhaul.

For the broader AI ecosystem, the case spotlights the murky boundary between cloud providers and frontier labs. If exclusive cloud discounts and board-level coordination are successfully framed as anticompetitive, it could force cloud giants like Microsoft, Amazon, and Google to rethink how they structure sweetheart infrastructure deals with AI startups.