Eric Zelikman
About Eric Zelikman
Eric Zelikman is co-founder and CEO of humans&, a human-centric AI lab. His personal site says he was previously at xAI and Stanford. He is the author of STaR (Self-Taught Reasoner) and contributed to Grok's reasoning and agent training.
According to Scale Venture Partners, at xAI he led post-training for Grok 2 and developed the agent RL recipe for Grok 4 with small teams. He also co-authored Quiet-STaR, a paper on reasoning and reflection in language models.
Crunchbase News reports that humans& was founded in September 2025 and raised a $480M seed round at a $4.48B valuation. The company's site says the round was led by SV Angel and co-founder Georges Harik. It lists NVIDIA, Jeff Bezos, GV, Emerson Collective and Forerunner among its investors.
Zelikman has not published a list of his angel investments or described an angel program. The one investment we can confirm is RadixArk. Dealroom lists him among the company's investors. The Angel Registry newsletter also lists him as an investor in the round.
RadixArk is a Palo Alto AI infrastructure company that builds open, scalable systems for training, deploying and running frontier models. FinSMEs reports a $100M Seed round at a $400M valuation. RadixArk's announcement says Accel led the round and Spark Capital co-led it. Zelikman publicly endorsed the team on X and pointed to its open source infrastructure work. The Lounge deals desk lists this round as 2026-01, but press coverage of the launch is dated May 2026.
Zelikman has not made public statements about the stage, sectors, geography or check size he prefers. His only confirmed investment is a seed-stage AI infrastructure company. His own work centers on reasoning, post-training and human-centric AI models. That is not a stated investing thesis. His check size is not public.
- RadixArk: AI infrastructure company building open systems for training and serving frontier models. It raised a $100M Seed at a $400M valuation, led by Accel and co-led by Spark Capital.
- zelikman.me
- linkedin.com/in/ericzelikman
- x.com/ericzelikman/status/2051730946098176035
- scalevp.com/insights/announcing-our-investment-in-humans
- news.crunchbase.com/ai/humans-raises-huge-seed-round-unicorn-valuation
- humansand.ai
- finsmes.com/2026/05/radixark-raises-100m-in-seed-funding.html
- dealroom.co/companies/radixark
Investing activity
Eric Zelikman appears in 1 AI deal tracked by the Lounge deals desk, rounds totalling $100M. The rounds are mostly Seed, with a median round size of $100M. The most recent is RadixArk (Seed, $100M, Jan 2026).
Eric Zelikman most often invests alongside Spark Capital, Accel, AMD and Hock Tan, and the companies they back on Lounge are mostly in AI Infrastructure.
Deals
Frequently asked questions about Eric Zelikman
Who is Eric Zelikman?
He is co-founder and CEO of humans&, a human-centric AI lab. He previously worked at xAI and Stanford and wrote the STaR reasoning paper.
Has Eric Zelikman invested in RadixArk?
Yes. Dealroom lists him as an investor in RadixArk's $100M Seed round. The Angel Registry newsletter also lists him in the round.
What is Eric Zelikman's angel check size?
It is not public. He has not stated a check size or an investing range.
What stage and sectors does Eric Zelikman invest in?
He has not published a thesis. His one confirmed investment is a seed-stage AI infrastructure company.
Should AI founders pitch Eric Zelikman?
He is a full-time CEO and researcher focused on reasoning and human-centric models, so technical founders in those areas may be the most relevant. He has not said he takes cold pitches. A warm introduction through the shared network is the safer route.
Is Eric Zelikman an angel investor?
Yes. Eric Zelikman invests personally as an angel.
What AI companies has Eric Zelikman invested in?
Eric Zelikman's AI investments include RadixArk. The 1 round on Lounge are listed on this page with amounts, dates and co-investors.
What stage does Eric Zelikman invest at?
In the rounds tracked on Lounge, Eric Zelikman has invested at Seed, with a median round of $100M.
Who does Eric Zelikman co-invest with?
Eric Zelikman's most frequent co-investors on Lounge are Spark Capital (1 deal), Accel (1 deal), AMD (1 deal), Hock Tan (1 deal) and John Schulman (1 deal).
How can founders reach Eric Zelikman?
Founders on Lounge can see Eric Zelikman's contact details in AI Investor Contacts (paid plans), check for a warm introduction through members who worked with them under Warm Paths, and add Eric Zelikman to their Investor Pipeline to track the conversation.