• Mark Zuckerberg's Meta urged California to halt OpenAI's transition to a for-profit company.
• In doing so, Zuckerberg sided with his occasional nemesis, Elon Musk, who also wants to stop OpenAI.
• It seems the two tech billionaires have finally found some common ground.

Meta CEO Mark Zuckerberg and X owner Elon Musk have long-standing beef about everything from artificial intelligence to how they run their respective social media platforms.

While that feud has lasted for the better part of a decade — and has even threatened to get physical — the two tech billionaires now agree on at least one thing: their competitor, OpenAI, should remain a nonprofit.

Zuckerberg's Meta asked the California attorney general on Friday to stop OpenAI from becoming a for-profit company. Meta accused Sam Altman's company of "taking advantage" of its status as a nonprofit to raise billions.

"OpenAI wants to change its status while retaining all of the benefits that enabled it to reach the point it has today. That is wrong. OpenAI should not be allowed to flout the law by taking and reappropriating assets it built as a charity and using them for potentially enormous private gains," Meta said in the letter to California Attorney General Rob Bonta.

OpenAI is one of Meta's biggest competitors in the AI tech race.

"Failing to hold OpenAI accountable for its choice to form as a nonprofit could lead to a proliferation of similar startup ventures that are notionally charitable until they are potentially profitable," Meta wrote in the letter.

With that, Zuckerberg sided with Musk, who is engaged in an ongoing legal fight to prevent OpenAI from becoming a for-profit.

Musk, one of 11 OpenAI cofounders who split from the company early on, launched a second bid in November to stop OpenAI from making the transition, asking a court for an injunction against the company.

The injunction request also argues that OpenAI and Microsoft, the largest corporate investor in the AI startup, have worked together to build a "for-profit monopoly," engaging in anti-competitive behavior that also targets xAI, Musk's artificial intelligence venture.

OpenAI has fought back. On Friday, it published a blog post titled "Elon Musk wanted an OpenAI for-profit." The post includes a series of emails and messages between Musk and other cofounders, including Altman, going back as far as November 2015, a month before the company was founded.

In one of those emails, Musk responded to Altman's proposal to start a Delaware-based nonprofit: "Also, the structure doesn't seem optimal," Musk wrote.

Musk left the organization in 2018 in part because he believed OpenAI's "probability of success was 0," according to an OpenAI blog post from March. Musk has accused OpenAI of straying from its original mission to develop an artificial general intelligence that is safe and benefits humanity.

Almost a decade after its founding as a nonprofit, OpenAI is now eyeing the switch to a for-profit venture to generate more investor capital. In October, the company announced a $6.6 billion funding round, raising OpenAI's valuation to $157 billion. That investment, however, comes with a stipulation that OpenAI become a for-profit within two years.

Meanwhile, Meta said it plans to pour as much as $37 billion on infrastructure costs alone this year, largely related to AI. Musk's xAI told investors last month that it secured $5 billion in funding.

Musk and spokespeople for Meta and OpenAI did not respond to a request for comment.