Sam Altman, president of Y Combinator, pauses during the New Work Summit in Half Moon Bay, California, U.S., on Monday, Feb. 25, 2019.
David Paul Morris | Bloomberg | Getty Images

OpenAI’s ChatGPT unleashed an arms race among Silicon Valley companies and investors, sparking an A.I. investment craze that proved to be a boon for OpenAI’s investors and shareholding employees.

But CEO and co-founder Sam Altman may not notch the kind of outsize payday that Silicon Valley founders have enjoyed in years past. Altman didn’t take an equity stake in the company when it added the for-profit OpenAI LP entity in 2019, Semafor reported Friday.

OpenAI launched as a non-profit model in 2015 with backing from Tesla CEO Elon Musk, who committed $1 billion to OpenAI, Semafor reported. But Musk was unhappy with OpenAI’s growth, which he assessed as “fatally behind” Google‘s work in AI, Semafor reported.

In early 2018, Musk proposed assuming control over OpenAI and running it himself, Semafor reported, an offer that was rebuffed by Altman and the company’s other team.

The private rift reportedly prompted Musk’s departure. Musk reneged on a publicly announced funding arrangement, providing only $100 million of his planned $1 billion in support, according to the report.

Altman was already independently wealthy given his long career launching or investing in tech startups. That played into his decision to not seek equity when the transformation was underway, people familiar with the matter told Semafor.

Months after adding a for-profit entity, in Jul. 2019, OpenAI took a $1 billion investment from Microsoft, which has since embedded the company’s technologies into its products.

While Altman’s lack of initial equity reportedly gave investors pause in 2019, the fanfare associated with ChatGPT’s launch has likely tempered those concerns.

OpenAI is now looking to tender shares at a $29 billion valuation, more than double what it was worth in 2021, The Wall Street Journal reported.

OpenAI and Musk didn’t immediately respond to CNBC’s request for comment.

Read more at Semafor.