Series B Funding Hits $48 Billion in 2026, but Deal Count Slides

By Grace Kim

U.S. startups have pulled in roughly $48 billion in Series B-stage financings so far in 2026, the highest tally in years — even as round counts sit below year-ago levels and track toward a multiyear low. The numbers come from Crunchbase data covering deals that may include financings with Series B characteristics but not explicitly announced as such.

The paradox is simple: more money, fewer rounds. Venture capital is concentrating heavily around a handful of AI leaders, and that concentration is reshaping who gets funded at the Series B stage.

Where did the small rounds go?

Small and mid-sized Series B rounds are disappearing fastest.

So far this year, less than a third of deals in Crunchbase's sample set — which included U.S. Series B rounds of $1 million or more — were for under $30 million. Between 2021 and 2025, rounds in that range accounted for about half of all deals.

The bottom of the market has thinned out even more. This year saw just 26 Series B rounds under $10 million in the sample set.

The takeaway: sub-$30 million rounds, once half the market, are now a shrinking minority.

How big are the biggest rounds?

Very. At least 110 companies have raised rounds of $100 million or more around the Series B stage so far in 2026 — roughly a quarter of all deals.

The largest by far was a $12 billion round for Prometheus, Jeff Bezos' physical AI startup that launched last year. Prometheus did not publicly label the round a Series B, but multiple reports, including an Axios post, described it as one.

Two companies tied for next-biggest fundraiser:

• World Labs, the model developer led by AI pioneer Fei-Fei Li, closed $1 billion in February.
• Valar Atomics, a nuclear energy startup, secured $1 billion in Series B funding across tranches this year, with Sequoia Capital as lead investor.

The takeaway: nine-figure rounds are now routine, and one round reached twelve figures.

Is this an AI story?

Largely, yes. About two-thirds of Series B funding has gone to AI-focused startups so far this year, per Crunchbase data. In 2025, about half of investment went to AI categories.

Round counts tell the same story. More than half of all reported U.S. Series B deals in 2026 have gone to AI companies.

The takeaway: AI's share of Series B dollars jumped from roughly half to two-thirds in a single year.

What does this mean for founders?

The climate is bullish for Series B investment overall, particularly for AI startups with demonstrated traction. It looks especially favorable for companies that already raised considerable sums at seed and Series A.

For everyone else, the picture is tougher. Startups seeking smaller Series B rounds face the weakest market in years, because in the current AI-driven cycle investors are increasingly focused on writing big checks for high-valuation companies.

The takeaway: the market rewards scale and momentum, not modest checkpoints.

Crunchbase has published its underlying dataset as a saved query, "US Series B Funding, 2026," for readers who want to dig into the deal-level detail.

Expect the split to widen: as long as capital keeps pooling around proven AI franchises, the Series B bar will keep rising for everyone outside that cohort.