Musk v Altman et al

Musk v. Altman et al. (Case No. 4:24-cv-04722-YGR) is a landmark lawsuit in which Elon Musk alleges that OpenAI cofounders Sam Altman and Greg Brockman breached a charitable trust and were unjustly enriched by Musk's donations, after promising that OpenAI would remain a nonprofit. Originally filed as a 26-claim complaint including fraud and constructive fraud, the case was narrowed to two claims on April 24–25, 2026, when Musk voluntarily dismissed his fraud claims ahead of trial. A bench trial with advisory jury began April 27, 2026 before Judge Yvonne Gonzalez Rogers in the U.S. District Court for the Northern District of California (Oakland). bench trial with advisory jury began April 27, 2026 before Judge Yvonne Gonzalez Rogers in the U.S. District Court for the Northern District of California (Oakland). On April 28, 2026, Musk took the stand, testifying that Altman and Brockman illegally "looted" OpenAI's charitable assets. On April 30, 2026, Musk appeared to admit under cross-examination that xAI had used OpenAI models to train its own through distillation — a technique where one AI model trains another — calling it a standard industry practice. Judge Gonzalez Rogers admonished both sides to refrain from using social media to inflame the dispute and warned OpenAI not to take inconsistent positions in her courtroom.

Field	Detail
Case Name	Musk v. Altman et al.
Court	U.S. District Court, Northern District of California (Oakland)
Case Number	4:24-cv-04722-YGR
Judge	Hon. Yvonne Gonzalez Rogers
Filed	August 5, 2024
Plaintiff	Elon Musk
Defendants	OpenAI Inc., OpenAI L.L.C., OpenAI Startup Fund I L.P., Sam Altman, Greg Brockman, Microsoft Corporation
Claims	Breach of charitable trust, unjust enrichment (fraud claims dropped April 25, 2026)
Status	Bench trial with advisory jury begins April 27, 2026 (narrowed to 2 claims after Musk dropped fraud claims)
Key Pre-Trial Rulings	Jan. 15, 2026: Judge Gonzalez Rogers largely denied OpenAI's summary judgment motion, finding disputed facts on charitable trust, fiduciary duties, and reliance; Microsoft won partial summary judgment but aiding-and-abetting claim survived; March 2026: Court admitted expert testimony from Dr. Stuart Russell (UC Berkeley, AI safety) on AI company incentives, and Dr. C. Paul Wazzan (damages, $25B–$134B range)

Background

Musk co-founded OpenAI in December 2015 as a nonprofit research laboratory dedicated to ensuring AI benefits all of humanity. He resigned from the board in February 2018. The complaint alleges that Musk donated approximately $38–45 million based on explicit promises that OpenAI would remain a nonprofit and open-source. In 2019, OpenAI created a capped-profit subsidiary and accepted a $1 billion investment from Microsoft. By 2025, OpenAI had converted to a fully for-profit entity valued at over $800 billion.

Claims

As of April 25, 2026, the case has been narrowed to two remaining claims after Musk voluntarily dismissed his fraud claims:

• Breach of charitable trust: OpenAI's founders violated their founding agreement to keep OpenAI nonprofit and open, and Musk's donations were made in charitable trust for a nonprofit purpose.
• Unjust enrichment: Altman, Brockman, and OpenAI were unjustly enriched by Musk's charitable donations after abandoning the nonprofit mission.

Dismissed claims (April 24–25, 2026):

• Fraud and constructive fraud: Musk voluntarily dismissed these claims on April 24–25, 2026, stating he wanted to "streamline" the case. Judge Gonzalez Rogers approved the dismissal.

Earlier dismissed claims:

• Aiding and abetting breach: Previously trimmed along with other claims as the case narrowed toward trial.
• Promissory estoppel and breach of contract: Previously subsumed or trimmed as the case evolved toward the charitable trust theory.

Remedies Sought

Musk seeks:

• Reverting OpenAI to nonprofit status and unwinding the for-profit conversion
• Removing Sam Altman as director of the nonprofit and officer of the for-profit entity, and stripping his equity
• Removing Greg Brockman as president and stripping his equity
• Billions in financial disgorgement — up to $134 billion per a January 2026 expert filing
• Disgorgement of ill-gotten gains

Pre-Trial Developments

In the final weeks before trial, several significant filings and rulings shaped the case:

• April 7, 2026: Musk amended his requested remedies, dropping personal monetary claims (previously seeking approximately $134 billion in disgorgement) and focusing instead on equitable relief, including restructuring OpenAI to unwind the for-profit conversion.
• April 10, 2026: OpenAI responded by calling Musk's amendment a "legal ambush" and "sandbagging," accusing him of contradicting prior statements about his sought remedies.
• April 17, 2026: Judge Gonzalez Rogers considered bifurcating the trial into a liability phase followed by a remedies phase, and barred both parties from mentioning remedies to the advisory jury during the liability phase.
• April 24-25, 2026: Musk voluntarily dismissed his fraud and constructive fraud claims, narrowing the case to two remaining claims: breach of charitable trust and unjust enrichment. The strategic move was intended to streamline the trial by focusing on outcomes rather than intent.

Key evidence expected at trial includes a 2017 Greg Brockman diary entry calling the nonprofit commitment "a lie," a 2017 Sam Altman email expressing enthusiasm for the nonprofit structure amid Musk's funding threats, and unsealed 2025 discovery materials (emails, texts, Slack messages) alleging public nonprofit promises masked private for-profit plans. Judge Gonzalez Rogers cited "ample evidence" in her January 15, 2026 ruling denying most dismissal motions.

Expected witnesses include Musk, Altman, Microsoft CEO Satya Nadella, and former OpenAI executives Mira Murati and Ilya Sutskever. Pretrial filings also revealed personal details including Shivon Zilis (OpenAI board member and mother of four of Musk's children) relaying information to him, and text messages from Mark Zuckerberg offering Musk favors including DOGE assistance and a joint bid for OpenAI.

As of April 23, 2026, prediction markets (Polymarket) gave Musk approximately a 35% chance of winning.

Trial Schedule

• April 27, 2026: Jury selection begins at 8:00 a.m. PT in Oakland federal courthouse
• April 28, 2026: Opening statements expected
• Phase 1 (Advisory Jury Verdict): The jury will hear arguments on the two remaining claims (breach of charitable trust and unjust enrichment) and issue an advisory verdict that is non-binding on Judge Gonzalez Rogers. Approx. 100 potential jurors summoned from seven Bay Area counties; voir dire allows unlimited for-cause challenges and four peremptory challenges per side.
• Phase 2 (Remedies): If liability found, Judge Gonzalez Rogers will hear arguments on remedies and issue a final ruling, starting approximately May 18, 2026

Trial schedule: Monday–Friday, 8:30 a.m. to 1:40 p.m. PT, with two 20-minute breaks.

Key Evidence

• Greg Brockman's private diary entries documenting awareness of for-profit intentions before Musk's departure: "can't see us turning this into a for-profit without a very nasty fight" and calling it "morally bankrupt" to "steal" the company from Musk
• Communications involving Mark Zuckerberg and Shivon Zilis
• Testimony from former board members including Tasha McCauley regarding OpenAI's internal governance
• Expert witness testimony from Dr. C. Paul Wazzan (damages expert), who calculated potential damages up to $134 billion — comprising up to $109 billion from OpenAI and up to $25 billion from Microsoft — though this does not include punitive damages
• Potential testimony from Microsoft CEO Satya Nadella

OpenAI's Defense

OpenAI characterizes Musk's lawsuit as a "harassment campaign" driven by "ego, jealousy and a desire to slow down a competitor," suggesting Musk is using litigation to harm a rival through his own xAI company. OpenAI has filed counterclaims alleging Musk's anti-competitive behavior and has urged the California and Delaware attorneys general to investigate.

On January 8, 2026, Judge Gonzalez Rogers ruled that fraud claims require jury resolution due to factual disputes, allowing the case to proceed to trial. However, on April 24–25, 2026, Musk voluntarily dismissed his own fraud claims to streamline the case, reducing it to two claims (breach of charitable trust and unjust enrichment).

• April 27, 2026: Bench trial with advisory jury begins at 8:00 a.m. PT in Oakland federal courthouse; jury selection commences

Pre-Trial Rulings

Summary Judgment (January 15, 2026)

Judge Gonzalez Rogers largely denied OpenAI's motion for summary judgment on January 15, 2026, finding genuine disputes of material fact on whether a charitable trust existed, whether defendants breached fiduciary duties, and whether Musk reasonably relied on Altman's representations. Microsoft won a partial victory, but the claim that it aided and abetted OpenAI's breach survived.

Expert Testimony Rulings

The court admitted testimony from two key experts:

• Dr. Stuart Russell, UC Berkeley professor and AI safety authority, will testify that AI companies have strong incentives to pursue artificial general intelligence despite safety risks, supporting Musk's argument that OpenAI's for-profit pivot created dangerous misalignment.
• Dr. C. Paul Wazzan, Musk's damages expert, calculated potential recovery between $25 billion and $134 billion, with the upper range divided between OpenAI's gains ($109 billion) and Microsoft's potential liability ($25 billion). The judge found Wazzan's valuation methodology adequately supported despite OpenAI's objections about lack of accepted standards for valuing Silicon Valley startups.

April 30, 2026: Distillation Admission

On the fourth day of trial (April 30, 2026), Musk faced cross-examination from OpenAI attorney William Savitt about whether xAI had used OpenAI's models through distillation — a technique where a smaller AI model is trained to mimic the behavior of a larger model. The exchange proceeded as follows:

• Savitt: "Has xAI done that [distillation] with OpenAI?"
• Musk: "Generally all the AI companies [do that]."
• Savitt: "So that's a yes."
• Musk: "Partly."

When asked whether OpenAI technology had been used in any way to develop xAI, Musk replied that "it is standard practice to use other AIs to validate your AI." The admission was significant given OpenAI's previous efforts to block distillation by competitors, particularly Chinese AI labs, and the Trump administration's April 2026 memo pledging to share information with US companies about foreign distillation threats.

The exchange was part of OpenAI's broader effort to challenge Musk's credibility as an AI safety advocate, building on the April 29 cross-examination about Musk's opposition to Colorado's anti-algorithmic discrimination law.

Significance

This case is one of the most consequential legal battles in AI industry history. A finding of liability could force OpenAI to abandon its for-profit structure, potentially unwinding its Microsoft partnership and reshaping AI company governance. Even an OpenAI victory will expose internal governance concerns through public trial evidence.

See Also

• Musk v. Altman Trial Begins (April 27, 2026)
• Musk v. Altman Trial Day 2: Musk Testifies (April 28, 2026)
• Musk v. OpenAI Trial Overview (April 2026)
• Musk v Altman et al (this page)

Colorado AI Law Cross-Examination

During Musk's cross-examination on April 29, 2026, OpenAI's counsel Marc Savitt raised Musk's opposition to Colorado's anti-algorithmic discrimination law, which xAI has been fighting against. Savitt suggested that Musk's purported commitment to AI safety is undermined by his company's resistance to AI regulation. The line of questioning was part of a broader effort to challenge Musk's credibility as an AI safety advocate.