8 startups Sam Altman invested in outside OpenAI in 2025
- lastmansurfing
- Dec 25, 2025
- 1 min read
The OpenAI CEO’s latest startup investments reveal a growing focus on energy, security and moonshot science beyond generative A.I.
Long before generative A.I. captured global attention, Altman built a reputation as a prolific angel investor whose bets helped shape the modern tech landscape, from early stakes in Stripe, Reddit and Instacart to later, high-conviction investments in nuclear energy and longevity science.
Altman’s 2025 investment activity has centered on startups in A.I.-driven security, biotechnology and nuclear fusion, according to Crunchbase data. These bets reflect not just a desire to diversify across cutting-edge industries, but also to champion “moonshot” ventures tackling some of today’s most complex challenges, from intelligence augmentation and clean energy to breakthroughs in human health.
Read more | OBSERVER