Early career In 2005, at the age of 19, Altman co-founded
Loopt, In February 2014, he became president of YC, replacing YC co-founder
Paul Graham, who had been his mentor. In October 2015, Altman was involved in expanding YC's scope. He invested in multiple startups such as
Stripe, Inc.. Several YC leaders expressed concern that Altman may have used these roles to prioritize his investments over other YC investors. In early 2020, Altman and YC terminated their relationship. Graham was "unambiguous that Altman was removed because of Y.C. partners' mistrust." In April 2012, Altman co-founded Hydrazine Capital with his brother, Jack Altman. The initial $21 million fund included a large part of the $5 million he got from selling Loopt, but most came from
Peter Thiel, his mentor and main backer in
Silicon Valley. Sam Altman invested 75 percent of the money in Y-Combinator companies. In 2023, when Hydrazine launched its fourth fund, the
University of Michigan endowment was the only outside investor. Its investments in Hydrazine were the largest the endowment has made. Altman debuted on the
Bloomberg Billionaires Index in March 2024 with an estimated net worth of $2 billion, primarily from his venture capital funds related to Hydrazine Capital. He was invited to attend the
Bilderberg Meeting in 2016,
2022, and
2023. presenting Altman with the
Ric Weiland Award in 2017
Biotech Altman has several other investments in companies including
Humane, which was developing a wearable AI-powered device; Retro Biosciences, a research company aiming to extend human life by 10 years;
Boom Technology, a
supersonic airline developer;
Cruise, a self-driving car company later acquired by
General Motors; and Helion Energy, an American fusion research company. During the
COVID-19 pandemic, Altman helped fund and create Project Covalence to help researchers rapidly launch clinical trials in partnership with TrialSpark, a clinical trial startup. During the depositor run on
Silicon Valley Bank in mid-March 2023, Altman provided capital to multiple
startups. Altman invests in technology startups and nuclear energy companies. Some of his portfolio companies include
Airbnb,
Stripe, and
Retro Biosciences. He also invested in charter city projects
Próspera and
Praxis, which have gotten additional financial support from author and former
Coinbase CTO
Balaji Srinivasan. Both cities have been linked by various publications and journalists to the Network State movement.
Reddit For eight days in 2014, Altman was the CEO of
Reddit, a
social media company, after CEO
Yishan Wong resigned. On July 10, 2015, he announced the return of
Steve Huffman as CEO. He remained on its board until 2022. Altman invested in multiple rounds of funding for Reddit (in 2014, 2015, and 2021). Prior to Reddit's
initial public offering in 2024, Altman was listed as its third-largest shareholder, with around 9% ownership.
Worldcoin In 2019, Altman co-founded the for-profit company Tools For Humanity with
Alex Blania (CEO) and others. The company promoted the
Worldcoin cryptocurrency and eye-scanning systems to provide
proof of personhood and authentication. However, it has engaged in deceptive marketing practices to drive sign-ups. By 2023, Tools For Humanity had scanned two million people's eyes and raised $250 million from several investors, including
Andreessen Horowitz and
Sam Bankman-Fried.
Kenya was one of the first countries to register WorldCoin. The promise of free money led to rapid growth in Kenya until WorldCoin promotion was paused by regulators. Citing legal concerns over
biometric data privacy and potential fraud concerns, regulators in France, the United Kingdom, Bavaria, South Korea, Spain, Portugal, and Hong Kong have investigated or suspended WorldCoin. WorldCoin has never been offered in the United States and the company limits its disclosures due to regulatory scrutiny. He also invested in
Exowatt, a solar energy startup that aims to provide clean energy to data centers. In March 2021, Altman and investment banker Michael Klein co-founded AltC Acquisition Corp, a
special-purpose acquisition company (SPAC), where he was also the CEO. In May 2024, Oklo Inc. completed a merger with the SPAC to become a public company. Altman remained as chairman of Oklo following the merger until stepping down in April 2025 to "avoid conflict of interest" and "open up opportunities for future deals between OpenAI and Oklo."
OpenAI OpenAI begins OpenAI was initially founded as a
nonprofit organization by Altman,
Greg Brockman,
Elon Musk,
Jessica Livingston,
Peter Thiel,
Microsoft,
Amazon Web Services,
Infosys, and YCResearch. Altman tenaciously recruited
Ilya Sutskever and
Dario Amodei by giving them attention and offering YC stock. In his early conversations with Musk, he framed OpenAI as competing against
Google's AI development. Google was far ahead; Musk and Altman modeled their strategy after the
Manhattan Project with an emphasis on recruiting AI technology leaders and convincing the world that they were protecting against the AI threat. In 2019, OpenAI said that $130 million of the pledged funds had been collected.
TechCrunch reported that YC Research never contributed any of their pledged funds. Altman said in 2015 that they were partly motivated by concerns about
AI safety and
existential risk from artificial general intelligence. Altman highlighted the importance of
open-source and making AI for collective good for humanity, above financial stakeholders in response to mitigation of risk. Altman noted it will be a decades-long project that eventually surpasses human intelligence.
Walter Isaacson opined that Altman had "Musk-like intensity".
Deepening investment in OpenAI In 2018, Musk, a long-time personal friend of Altman's, resigned from his Board of Directors seat, citing "a potential future
conflict [of interest]" with his role as CEO of
Tesla due to
Tesla's AI development for self-driving cars. OpenAI executives, including Altman, dismissed these claims in a blog post. The post said that the startup received only $45million from Musk instead of his pledged $1billion, and that Musk proposed to merge it with Tesla. In March 2019, Altman left Y Combinator and began focusing full-time as CEO of OpenAI. Through 2017, Brockman and Sutskever oversaw the day to day business and Altman touched base approximately once a week. Sutskever opposed Altman moving to an AI role because Altman's motivation were unclear and it opened the possibility of an "AI dictator". The three leaders made an informal agreement that Altman would step down if the other two requested. Altman stated that even a billion dollars may turn out to be insufficient, and that the lab may ultimately need "more capital than any non-profit has ever raised" to achieve
artificial general intelligence (AGI).
Release of ChatGPT In December 2022, OpenAI received widespread media coverage after launching a free preview of ChatGPT, a new AI
chatbot based on GPT-3.5. According to OpenAI, the preview received over a million signups within the first five days. According to anonymous sources cited by
Reuters in December 2022, OpenAI Global, LLC was projecting $200 million of revenue in 2023 and $1 billion in revenue in 2024. , is shown. As of March 2025, 58% of those under 30 have used the chatbot. Altman testified before the
United States Senate Judiciary Subcommittee on Privacy, Technology and the Law on May 16, 2023, about issues of AI oversight. After the success of ChatGPT, Altman made a world tour in May 2023, during which he visited 22 countries and met multiple leaders and diplomats, including British prime minister
Rishi Sunak, French president
Emmanuel Macron, Spanish prime minister
Pedro Sánchez, German chancellor
Olaf Scholz, Indian prime minister
Narendra Modi, South Korean president
Yoon Suk-yeol, Israeli president
Isaac Herzog, and
European Commission president
Ursula von der Leyen. Altman stated that being CEO was fun until the release of ChatGPT; then the decisions became much more difficult.
Removal and reinstatement as OpenAI CEO On November 17, 2023, OpenAI's board, composed of researcher
Helen Toner,
Quora CEO
Adam D'Angelo, AI governance advocate Tasha McCauley, and, most prominently in the firing, OpenAI co-founder and chief scientist
Ilya Sutskever, announced that they had made the decision to remove Altman as CEO and Greg Brockman from the board, both of whom were co-founders. The announcement cited that Altman "was not consistently candid in his communications". According to
The New Yorker, Altman returned to his home and coordinated with consultant
Chris Lehane,
Airbnb executive
Brian Chesky, and a team of staff to implement a strategy for his reinstatement. Altman stated that his team was focused on damaging interim CEO Mira Murati's reputation. On November 20, 2023, Microsoft CEO
Satya Nadella announced that Altman would be joining Microsoft to lead a new advanced AI research team. Two days later, OpenAI employees published an
open letter to the board threatening to leave OpenAI and join Microsoft, where all employees had been promised jobs, unless all board members step down and reinstate Altman as CEO. 505 employees initially signed, which later grew to over 700 out of 770 total employees. This included Ilya Sutskever, who initially advocated for firing Altman, but then stated on Twitter "I regret my participation in the board's actions." On November 20, the board reached an agreement where most of the existing member departed, an independent investigation into Altman's conduct was planned and Altman and Brockman returned to their roles. On November 21, 2023, after continued negotiations, Altman and Brockman returned to the company. D'Angelo remained on the board and was joined by
Bret Taylor (as chairman) and
Lawrence Summers. Brockman took a sabbatical from August 2024 to November 2024. In May 2024, after
OpenAI's non-disparagement agreements were exposed, Altman was accused of lying when claiming to have been unaware of the equity cancellation provision for departing employees who don't sign the agreement. Also in May, former board member
Helen Toner explained the board's rationale for firing Altman in November 2023. She stated that Altman had withheld information, for example by not informing the board in advance of ChatGPT's release and by not disclosing his ownership of OpenAI's startup fund. She also alleged that two executives in OpenAI had reported "psychological abuse" from Altman, and provided screenshots and documentation to support their claims. She said that many employees feared retaliation if they didn't support Altman, and that when Altman was Loopt's CEO, the management team asked twice to fire him for what they called "deceptive and chaotic behavior".
Elon Musk lawsuit On April 27, 2026,
jury selection began in OpenAI co-founder Elon Musk's lawsuit against OpenAI and its current executives, including Altman. On April 28, 2026, trial testimony was by now underway, with Elon Musk beginning his testimony against Altman and OpenAI. On April 30, 2026 Musk would enter his third day of testimony. ==Political engagement==