Anthropic Cofounder Tom Brown Holds More Shares Than CEO Dario Amodei

By Olivia Hart

Anthropic cofounder Tom Brown owns about 244 million shares of the AI startup — more than CEO Dario Amodei — according to the company's S-1 filed Monday. At the expected $1.5 trillion IPO valuation, Brown's stake alone could be worth roughly $24 billion, a figure larger than the market capitalization of most companies in the S&P 500.

Brown co-founded Anthropic with the Amodei siblings and four others in January 2021. He serves as chief compute officer, leading the technical organization responsible for what the filing describes as "securing, scaling, and effectively using" Anthropic's computing resources. He is little known outside the company, yet his disclosed holdings narrowly top those of all six other cofounders.

His credentials predate Anthropic. According to the S-1, Brown led the engineering of GPT-3 at OpenAI. He and Dario Amodei also co-invented what Anthropic calls "deep RLHF," which the company said was central to transforming base large language models into conversational assistants such as Claude.

How are the founders' stakes divided?

The seven cofounders each hold roughly 232 million to 243 million shares — a distribution far more even than typical Silicon Valley founder allocations. Snap's Evan Spiegel and Bobby Murphy, for comparison, retained super-voting stock controlling about 89% of voting power after their 2017 IPO. What makes Anthropic unusual, per Business Insider's analysis of the filing, is both the number of founders with huge stakes and how evenly they are divided.

The disclosed ranking, by beneficial ownership:

• Tom Brown, chief compute officer: ~244 million shares
• Christopher Olah, cofounder: ~242.9 million shares
• Jared Kaplan, chief science officer: ~242.4 million shares
• Jack Clark, cofounder: ~242.3 million shares
• Daniela Amodei, president: ~241.4 million shares
• Dario Amodei, CEO: ~240.6 million shares, plus voting proxies over another 4.6 million

The filing does not disclose the expected IPO price or the number of shares to be sold, so no exact dollar values are yet possible. That omission matters; the $1.5 trillion figure remains an expectation, not a priced deal. Anthropic was valued at $965 billion in May and has applied to list on Nasdaq under the ticker "ANT," with the offering expected within weeks.

In plain terms: even the smallest founder stake could be worth more than $23 billion if the valuation holds.

How much control will the founders keep?

The founders' influence will extend far beyond their economic stakes. Immediately before the IPO, Anthropic plans to issue a special Class F share to an LLC controlled by the seven cofounders. That single share will carry 50.1% of Anthropic's total voting power on matters submitted to stockholders generally, including the election of directors other than those selected by Anthropic's Long-Term Benefit Trust.

In another unusual commitment, Anthropic says each cofounder has pledged to dedicate 80% of their personal equity to philanthropic causes. The filing does not detail the mechanics or timing of those pledges — a caveat worth noting before treating the windfalls as fully private fortunes. Public investors, meanwhile, will hold voting power on ordinary matters only within a structure where seven people control the majority outright.

Who else wins in the IPO?

Amazon and Google will each own more than 5% of Anthropic after IPO conversions. At a $1.5 trillion valuation, each stands to gain more than $75 billion in the offering. Google owned 14% of the company last year, according to legal filings, making it one of Anthropic's largest strategic backers.

Among venture firms, the stakes and sums are unusually large:

• Lightspeed Venture Partners is the largest venture shareholder at almost 2%, per a person familiar with the matter; it led a round at a $61.5 billion valuation in late 2024.
• Spark Capital partner Yasmin Razavi sits on Anthropic's board; Spark was the first firm to invest, at a $4.5 billion valuation in 2023, and has invested across at least six financings since.
• Iconiq invested $6 billion for a stake between 1.5% and 2%, per a person familiar with the matter.
• Coatue has invested $4.75 billion.
• Menlo Ventures led a 2024 round at roughly an $18 billion valuation and has since invested over $1.3 billion for a 1.5%-2% stake.
• Bessemer Venture Partners first invested in the 2024 Series D and has spent around $800 million — its largest investment to date — for nearly 1%.
• Sound Ventures invested more than $400 million.

Other major shareholders include Altimeter, Dragoneer, Greenoaks, Sequoia Capital, Salesforce Ventures, Mubadala and Founders Fund.

The filing's silence on share counts and pricing means the final wealth transfers remain estimates until Anthropic sets terms. What is already fixed is the structure: seven founders, majority control through one Class F share, and a philanthropy pledge covering 80% of their equity.