This brother and sister co-founded Anthropic five years ago. Now they are worth $19b each

Anthropic’s seven co-founders each hold roughly 1.4 per cent of the company, its IPO filing revealed, giving them individual fortunes of more than $US13 billion ($18.5 billion).

That vaults all of them, including siblings Dario and Daniela Amodei, among the top 300 people on the Bloomberg Billionaires Index, and makes them richer than well-known finance billionaires like Bill Ackman and Stan Druckenmiller.

The fortunes, which are based on Anthropic’s $US965 billion valuation in its last funding round, jumped from Bloomberg’s previous calculation of $US8 billion each. If Anthropic succeeds in reaching a $US2 trillion valuation in its initial public offering — a number that was previously floated by investors — they would rise to more than $US27 billion each before accounting for dilution from newly issued shares, according to Bloomberg’s wealth index.

The founders’ net worth underscores the utter dominance of tech, and particularly artificial intelligence, in driving both the US stock market and wealth creation this year. Tech fortunes among the world’s 500 richest people gained a combined $US845 billion through the first nine months of 2026, while billionaires outside tech saw their average net worth shrink.

In a letter to potential shareholders, Anthropic’s co-founders said that AI and Anthropic “represents one of the greatest economic opportunities in history.”

Along with the Amodeis, the other Anthropic co-founders are Tom Brown, Jack Clark, Jared Kaplan, Sam McCandlish and Christopher Olah. All seven have pledged to dedicate 80 per cent of their personal equity in Anthropic to philanthropic causes, according to the filing.

The size of the founders’ stakes belies their control over the company. Under Anthropic’s proposed governance structure, each founder remains a member of the Founder LLC — which controls a Class F share carrying 50.1 per cent of shareholder voting power — as long as they retain at least 2 per cent of the number of Class A shares they held when the company goes public.

That means a founder could dispose of 98 per cent of their existing stake and still retain an equal say with the other founders over how that controlling share is voted.

The founders’ majority voting control is somewhat offset by Anthropic’s Long-Term Benefit Trust, however, which has the power to elect and remove four members of the company’s seven-person board. The trust is designed to continue indefinitely, while the founders’ special voting share will eventually expire once fewer than three qualifying founders remain, whether because of death, incapacity, resignation or because they have sold or given away more than roughly 98 per cent of the Class A shares they held at the IPO.

The trust is governed by five trustees, who largely select their own replacements.

San Francisco-based Anthropic was started in 2021 by a group of former OpenAI employees who left following disagreements over the company’s future direction. Anthropic had an $US80.7 billion net loss on revenue of $US16.3 billion in the first six months of 2026, versus a $US13 billion net loss on revenue of $US1.2 billion in the same period last year, the filing shows.

Anthropic confirmed that chief executive officer Dario Amodei and President Daniela Amodei sold some of their shares in the company’s tender offers in 2025 and 2026. Last year, Anthropic kicked off a $US157 million tender that saw both siblings unload some of their stock. This year, Anthropic did a $US4.7 billion tender; the Amodeis, chief financial officer Krishna Rao, and Holden Karnofsky, the spouse of Daniela Amodei, all sold shares in that offering.

Anthropic also paid $US5 million in regulatory filing fees on behalf of the Amodeis this year related to their acquisition and ownership of Anthropic securities.

It’s not just the founders who are getting rich: Anthropic’s employees and other option holders were sitting on about $US98 billion in potential gains from their stock options as of June, based on figures in the filing.

Those gains reflect how sharply the company’s value has risen since many employees received their stock options. Employees and other holders could buy the shares underlying their outstanding options at an average price of just $US2.89 a share as of June. Altogether, exercising those options would cost about $US5.2 billion — while on paper, the underlying shares are estimated to be worth more than $US103 billion.

Anthropic also operates a donation-matching program that lets employees pledge a portion of their equity awards to eligible charities, with the company matching those donations in shares of its non-voting Class N stock. In August, it recognised a $US2 billion expense tied to employee donations in that month that resulted in it issuing 28 million shares for matching purposes. The co-founders’ pledge to donate 80 per cent of their equity isn’t eligible for the matching program.