Meta boss Mark Zuckerberg wants to put the kibosh on Sam Altman-led OpenAI’s push to shed its non-profit status – a move that puts the tech titan on the same side as his longtime rival Elon Musk.

The parent company of Facebook and Instagram warned that allowing the ChatGPT maker’s planned switch to a for-profit structure would have “seismic implications for Silicon Valley,” according to a letter sent to California Attorney General Rob Bonta.

“OpenAI should not be allowed to flout the law by taking and re-appropriating assets it built as a charity and using them for potentially enormous private gains,” Meta wrote in the letter, which was dated last Thursday and first reported by the Wall Street Journal.

Mark Zuckerberg’s Meta asked the California attorney general to intervene and block OpenAI from becoming for-profit.Bloomberg via Getty Images

Earlier this month, Musk and former OpenAI board member Shivon Zilis asked a federal judge in San Francisco to block the pioneering AI firm from becoming a for-profit.

His attorneys likened OpenAI to a “Frankenstein, stitched together from whichever corporate forms serve the pecuniary interests of Microsoft and Altman at any given moment.”

The injunction filing was an escalation in Musk’s lawsuit against OpenAI – which he co-founded in 2015 but later turned against after clashing with Altman. Musk has since launched his own artificial intelligence startup, xAI.

Meta sided with Musk in its letter to Bonta despite Zuckerberg and Musk trading barbs in public and private for years — and nearly facing off in a cage match last year.

“Although we would also urge your office to take direct action, we believe that Mr. Musk and Ms. Zilis are qualified and well positioned to represent the interests of Californians in this matter,” the letter said.

Bonta’s office and OpenAI did not immediately return requests for comment on Meta’s letter.

Elon Musk is currently suing OpenAI.Getty Images

OpenAI, which has been led by a nonprofit board since 2015, is planning to restructure as a for-profit public benefit corporation. The firm’s nonprofit arm would continue to exist but would no longer be in control.

Altman’s firm fired back at the injunction request last week, publishing a trove of emails and texts while arguing that Musk initially supported for-profit status for OpenAI – but left after he lost a bid to secure full control and a majority stake.

OpenAI CEO Sam Altman has clashed with Elon Musk.AFP via Getty Images

Last week, Altman claimed that he’s “not that worried” about Musk’s influence over President-elect Trump’s administration.

Musk has emerged as a key adviser to Trump and is set to co-lead the Department of Government Efficiency (DOGE), which is tasked with eliminating government waste.

“It would be profoundly un-American to use political power, to the degree that Elon has it, to hurt your competitors and advantage your own businesses,” Altman said at a New York Times conference. “And I don’t think people would tolerate that. I don’t think Elon would do it.”