U.S. Series B funding concentrates around AI as deal count declines

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Series B funding in AI

Highlights

U.S. Series B funding has reached about $48 billion so far in 2026, the highest in years, despite a multiyear low in deal count.
Less than a third of 2026 Series B deals are under $30 million, while at least 110 companies raised $100 million or more, including Prometheus at $12 billion and World Labs at $1 billion.
AI startups account for about two-thirds of U.S. Series B funding in 2026, up from about half in 2025, reflecting intensified investor concentration in the sector.

Capital shifts toward larger late-stage rounds

As reported by Crunchbase News, U.S. companies at the Series B stage have raised about $48 billion so far in 2026, the highest total in years, even though the number of rounds is running below year-earlier levels and is on pace for a multiyear low.

A key factor behind that concentration is the decline in smaller and mid-sized financings. Less than a third of deals in the sample set are for under $30 million this year, compared with roughly half of deals between 2021 and 2025, based on Crunchbase data. The smallest Series B rounds are especially scarce, with just 26 rounds under $10 million in the sample set this year.

At the other end of the market, large financings remain common. At least 110 companies have raised $100 million or more around the Series B stage so far this year, representing roughly a quarter of all deals. The largest is Prometheus, which raised $12 billion, while World Labs closed a $1 billion round in February and Valar Atomics secured $1 billion across tranches this year with Sequoia Capital as lead investor.

AI startups dominate the funding environment

AI-focused startups account for about two-thirds of all U.S. Series B funding so far in 2026, underscoring how strongly investor appetite is centered on the sector. That share is up from about half of investment in 2025, showing that capital concentration around AI is intensifying rather than broadening.

AI companies also represent more than half of all reported U.S. Series B deals this year by round count. The overall picture suggests a supportive market for startups with proven traction, particularly those that have already raised substantial seed and Series A capital, while companies seeking smaller Series B rounds face a tougher environment as investors favor larger commitments to higher-valuation businesses.

In our earlier article on global cybersecurity funding in Q3 2026, we highlighted how total investment rose mainly because late-stage round sizes got bigger even as the number of deals declined. We also noted that AI-oriented and identity security startups captured much of the capital, alongside a pickup in large M&A that signaled ongoing consolidation in the sector.

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