Sam Altman’s Startup Portfolio: 12 Companies Owned By the OpenAI CEO

The OpenAI CEO's stakes in various startups are estimated to be worth more than $500 million.

Sam Altman in a blue suit.
Sam Altman appears for testimony before the Senate Judiciary Subcommittee on Privacy, Technology, and the Law May 16, 2023 in Washington, DC. Win McNamee/Getty Images

The viral success of OpenAI’s ChatGPT has made Sam Altman, the company’s co-founder and CEO, a household name and business celebrity.

Altman, 38, cofounded OpenAI with Elon Musk in 2015. Before running the artificial intelligence firm full-time, Altman was president of Y Combinator, one of the world’s most famous startup incubators, from 2014 to 2019. During that time, he led dozens of Y Combinator’s investments in early-stage companies and continued to invest in startups after leaving the firm.

Over the years, Altman has funded nearly 100 companies, according to Crunchbase. The majority of Altman’s portfolio companies are private, which makes it difficult to calculate his net worth. Per one estimate, the entrepreneur and investor is worth more than $500 million. Most of his wealth is tied to equity ownership in companies he backs. (Interestingly, Altman actually owns no equity in OpenAI, which was most recently valued at $29 billion, he said during a congressional hearing on May 16.)

Here are 12 companies that list Altman as an investor in fundraising rounds greater than $50 million, according to Crunchbase data:

Helion Energy: nuclear fusion energy

Helion Energy has a special place in Altman’s startup portfolio. The entrepreneur said in previous interviews that Helion is “more than an investment to me.” Altman invested $375 million in Helion in November 2021 in a series E round that valued the startup at $2.5 billion. He reportedly visits the company once a month and is actively involved in operations.

Neuralink: Brain-computer interface

Altman became an investor in Elon Musk’s brain implant startup, Neuralink, in July 2021 when the company raised a $205 million series C round. The company is developing an implantable wireless device that connects the human brain to a computer.

Reddit: social media

The Altman-era Y Combinator was a lead investor in Reddit’s $50 million series B round in 2014. Y Combinator also participated in the social media company’s $200 million series C fundraising round in July 2017. Altman was a board member of Reddit from 2014 to January 2022.

Wave Mobile Money: fintech

Wave Mobile Money is an African fintech startup developing apps for transferring and borrowing money.¬†Altman was a participating investor in the company’s series A round in September 2021, which raised $200 million.

Retro Biosciences: biotech

Retro Biosciences is a San Francisco-based startup developing cellular reprogramming, autophagy and plasma-inspired therapeutics. Altman was the lead investor in the company’s $180 million venture round in April 2022.

TrialSpark: biotech

TrialSpark is a New York-based biotech platform aiming at accelerating clinical trials using automation and data.¬†Altman invested in the company’s series B round in October 2018 and series C round in September 2021.

Hermeus: supersonic aviation

Hermeus is an aviation startup developing the world’s fastest supersonic jets. Altman was a lead investor in the company’s $100 million series B round in March 2022.

Humane: software and hardware

Humane is a platform that creates and sells consumer hardware and software. Altman has invested in the startup three times. He led the Humane’s $30 million series A round in September 2020 and participated in its $100 million series B in July 2021 and $100 million series C in March this year.

Alt: sports card trading

Alt is an alternative asset platform that allows consumers to trade and store sports cards. Altman participated in the company’s $75 million series B round in November 2021.

Asana: productivity management

Altman was a lead investor in Asana’s $50 million series C round in March 2016. He then participated in the company’s $75 million series D round in January 2018.

Aspen Neuroscience: biotech

Aspen Neurosciences is a San Diego-based biotech startup specializing in personalized cell therapies. Altman participated in the company’s $70 million series A fundraising in April 2020.

Rescale: cloud software

Rescale is a cloud platform designed for engineers and computer scientists in aerospace and energy industries to build custom applications. Altman has invested in Rescale four times since its first seed round in 2012. He most recently participated in a $55 series C round in November 2021.

Sam Altman’s Startup Portfolio: 12 Companies Owned By the OpenAI CEO