Series B Funding Rises While Deal Count Drops

In short, the current landscape of U.S. Series B startup funding in 2026 is defined by more money and fewer rounds, as venture capital investments remain heavily concentrated on a select group of artificial intelligence standouts.

According to Crunchbase data, investors have injected roughly $48 billion into Series B stage financings 1 so far this year, marking the highest total in years. Nevertheless, total round counts remain below figures from a year ago and are tracking toward a multiyear low.

Smaller Series B rounds grow scarcer

A sharp drop-off in small and mid-sized Series B rounds is one of the primary trends driving this concentration of capital.

Thus far this year, under a third of the deals in our sample set 2 were valued at less than $30 million. Conversely, Crunchbase figures indicate that rounds within this bracket represented roughly half of all transactions between 2021 and 2025.

The smallest Series B transactions have become especially rare, with our sample set recording only 26 rounds under $10 million this year.

Big rounds still a big thing

Conversely, extremely large Series B rounds remain exceptionally popular.

Around this stage, a minimum of 110 companies have secured funding rounds of $100 million or more thus far in 2026, translating to about a quarter of all deals.

Prometheus—the physical AI startup launched last year by Jeff Bezos—secured the largest by far, bringing in a $12 billion round 3.

World Labs, a model developer spearheaded by AI pioneer Fei-Fei Li, tied for the second-largest fundraiser by closing on $1 billion in February. Valar Atomics, a nuclear energy startup, likewise obtained $1 billion in Series B funding across multiple tranches this year, with Sequoia Capital acting as the lead investor.

To provide a broader overview, we have compiled a sample list of additional top U.S. Series B recipients for this year below.

Mostly an AI story

Unsurprisingly, analyzing the recipients of Series B funding reveals a heavily AI-centric group.

Crunchbase data shows that approximately two-thirds of Series B funding has been directed toward AI-focused startups so far this year. By comparison, roughly half of all investments went to AI categories throughout 2025.

Furthermore, AI companies dominated the round counts, accounting for more than half of all reported U.S. Series B deals in 2026.

Bullish climate for Series B

Taken together, these figures indicate a bullish environment for Series B investments, specifically for AI startups displaying proven traction. This climate appears especially advantageous for enterprises that have already accumulated substantial sums during their seed and Series A stages.

Even so, the current conditions are less than ideal for startups hunting for smaller Series B rounds. It appears that investors in the ongoing AI-centric cycle are increasingly prioritizing large checks for high-valuation businesses.

Related Crunchbase query:

• US Series B Funding, 2026

Illustration: Dom Guzman

?Frequently Asked Questions

01What is the current state of U.S. Series B funding in 2026?

U.S. Series B funding is seeing more total money invested—roughly $48 billion so far—but fewer total rounds are taking place, indicating a trend toward capital concentration.

02Which sector is dominating Series B funding?

AI-focused startups are driving the market, capturing about two-thirds of all Series B funding and over half of all reported deals so far in 2026.

03Are smaller Series B rounds still common?

No, small and mid-sized Series B rounds have grown increasingly scarce, with deals under $30 million making up less than a third of the sample set this year.

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1. May include rounds that have characteristics of Series B financings but were not explicitly announced as Series B deals.↩

2. Sample included U.S. Series B rounds of $1 million or more.↩

3. Prometheus did not publicly announce its $12 billion funding round as a Series B, but reports from multiple sources, including an Axios post, described it as Series B.↩