America’s youngest billionaires are priced by their last funding round

The 2026 Forbes 400 contains a record ten Americans under the age of 40. Seven made their money in artificial intelligence, and for most of them there is no share price anyone can check.

Steven Hao, 30, co-founder of Cognition, the company behind the Devin coding agent, is the youngest member, worth an estimated $5.8bn after a September funding round valued Cognition at $48bn. Palmer Luckey, 33, is worth $5.9bn after Anduril raised $5bn at a $61bn valuation in May.

Edwin Chen, 38, founder of the AI training-data company Surge AI, is worth $18bn. Four co-founders of Anthropic (Tom Brown, Daniela Amodei, Jack Clark and Sam McCandlish) tie at No 75 with $15.5bn apiece.

Of the under-40s, only two derive their wealth from publicly traded shares: Vlad Tenev of Robinhood ($7.1bn) and Lukas Walton, the Walmart heir ($44.4bn). The rest are valued from private funding rounds.

What a funding round measures

A venture round is a real transaction, but it is a narrow one. A handful of investors buy a small slice of a company, usually preferred stock with protections that ordinary shares lack, at a price negotiated in private.

That price is then applied to every share in the company, including the founders’ common stock, which cannot easily be sold. Imagine valuing every house on a street at the price fetched by the one that sold with a new kitchen and a buyer who had to have it.

Forbes and Bloomberg know this and usually apply discounts. Even so, the headline numbers still move in the jumps that funding rounds produce, which is why a founder can join the Forbes 400 in the week a round is announced.

Hao’s entry followed Cognition’s $2bn raise in September. Luckey’s followed Anduril’s round in May.

The SpaceX precedent

This summer showed what can happen when a big private valuation meets the public market. SpaceX listed on 12 June at a valuation of about $1.77tn, briefly traded above $2tn, and then fell by about half from its peak within weeks, dropping below its offer price by late July.

Independent analysts had argued before the listing that the private-market valuation was generous: Morningstar put fair value at $780bn.

SpaceX was hardly a typical start-up, and its share price tells you nothing in particular about Cognition, Anduril or Anthropic. But in a private round, the company and its new investors both want the number to be high. On a stock exchange, the price is also set by people who want to get out.

Estimates of estimates

The Anthropic tie is a small clue to how these figures are put together. None of the four has sold shares on a public market, so their fortunes depend on the company’s last private valuation and on assumptions about how much each owns. The same is true, to a greater or lesser degree, of most of the young names on the list.

Some of these companies are growing very fast, and a few may turn out to be worth more than their last round said. Hao and Luckey might yet look cheap. Until the shares trade, though, the Forbes numbers are a well-informed guess.

Sources

• Forbes: 10 under 40, the youngest billionaires on the 2026 Forbes 400
• Quartz: AI drives record 10 under-40 billionaires onto 2026 Forbes 400
• BigGo Finance: America’s 10 youngest billionaires
• Wikipedia: Initial public offering of SpaceX

Cover image: Alfred Twu, Wikimedia Commons, CC0. Cropped.