OpenAI has completed a deal that values the San Francisco artificial intelligence company at $80 billion or more, nearly tripling its valuation in less than 10 months, according to three people with knowledge of the deal.

The company would sell existing shares in a so-called tender offer led by the venture firm Thrive Capital, the people said. The deal lets employees cash out their shares in the company, rather than a traditional funding round that would raise money for business operations.

OpenAI, which declined to comment, is now one of the world’s most valuable tech start-ups, behind ByteDance and SpaceX, according to figures from the data tracker CB Insights.

The deal is another example of the Silicon Valley deal-making machine pumping money into a handful of companies that specialize in generative A.I. — technology that can generate text, sounds and images on its own. The funding boom kicked off early last year, after OpenAI captured the public’s imagination with the release of the online chatbot ChatGPT.

(The New York Times sued OpenAI and its partner, Microsoft, in December, claiming copyright infringement of news content related to A.I. systems.)

The deal comes at a critical time for OpenAI, providing it with an important vote of confidence after a year of controversy. In November, the company’s board fired Sam Altman, its chief executive, because it lost confidence in his leadership. The dismissal ignited a week of chaos and threw the company’s future into doubt, as employees threatened to resign in solidarity with Mr. Altman. Ultimately, he was reinstated and several board members resigned.

In an attempt to resolve last year’s turmoil, OpenAI hired the law firm WilmerHale to review the board’s actions and Mr. Altman’s leadership. WilmerHale is expected to finish its report on the episode early this year.

The company agreed to a similar deal early last year. The venture-capital firms Thrive Capital, Sequoia Capital, Andreessen Horowitz and K2 Global agreed to buy OpenAI shares in a tender offer, valuing the company at around $29 billion.

Thrive declined to comment.

Investors are eager to pour money into A.I. companies. Last January, Microsoft invested $10 billion in OpenAI, bringing its total investment in the San Francisco start-up to $13 billion.

Since then, Anthropic, an OpenAI rival, has raised $6 billion from Google and Amazon. Cohere, a start-up founded by former Google researchers, raised $270 million, bringing its total funding to more than $440 million, and Inflection AI, founded by a former Google executive, also raised a $1.3 billion round, bringing its total to $1.5 billion.

OpenAI appeared to be close to finalizing its latest deal in November, when Mr. Altman was unexpectedly fired. In the week that followed, the potential deal loomed over Mr. Altman’s efforts to negotiate his way back into the company. Before he was reinstated, over 700 of the company’s 770 employees signed a petition calling for his reinstatement.