Series B Funding Rises Despite Drop in Total Deals

Increased capital, reduced round volume. Summarized briefly, that describes the landscape of U.S. Series B startup financing in 2026, as venture capital heavily concentrates on a select group of artificial intelligence standouts.

Figures from Crunchbase indicate that investors have funneled approximately $48 billion into Series B stage financings 1 so far this year, marking the highest aggregate total in years. Nevertheless, the total number of rounds trails behind figures from a year ago and remains on track to hit a multiyear low.

Smaller Series B rounds grow scarcer

A significant reduction in small and mid-sized Series B rounds is fueling this trend of capital concentration.

Thus far this year, under a third of the transactions in our sample set 2 fell below the $30 million threshold. Conversely, Crunchbase records show that transactions within this financial bracket comprised roughly half of all deals between 2021 and 2025.

The most modest Series B agreements have become particularly rare, with our sample set recording a mere 26 rounds under $10 million this year.

Big rounds still a big thing

Conversely, exceptionally large Series B investments remain highly sought-after.

At this funding stage, a minimum of 110 companies have secured rounds totaling $100 million or more during the current year, translating to roughly one out of every four deals.

Prometheus, the physical AI startup established by Jeff Bezos last year, claimed by far the largest share with a $12 billion round 3.

World Labs, a model developer spearheaded by AI visionary Fei-Fei Li, shared the position of second-largest fundraiser after finalizing a $1 billion injection in February. Additionally, Valar Atomics, a nuclear energy startup, secured $1 billion across multiple tranches of Series B funding this year, with Sequoia Capital acting as the lead investor.

To provide a broader perspective, we have compiled a sample list below featuring additional top U.S. Series B recipients from this year.

Mostly an AI story

Unsurprisingly, analyzing the recipients of Series B funding reveals that the group is heavily weighted toward artificial intelligence.

According to Crunchbase data, roughly two-thirds of all Series B capital has gone to AI-focused startups this year. By comparison, AI categories captured about half of total investments throughout 2025.

Artificial intelligence enterprises also dominated in terms of total transaction volume, accounting for more than half of all reported U.S. Series B deals so far in 2026.

Bullish climate for Series B

Taken together, these metrics indicate an optimistic market environment for Series B investments, specifically targeting AI startups that can prove tangible traction. This climate appears especially advantageous for businesses that previously secured substantial funding at the seed and Series A stages.

Even so, the current conditions are less than ideal for startups pursuing smaller Series B financing. Within the framework of today’s AI-centric cycle, investors increasingly favor writing massive checks for companies commanding lofty valuations.

Related Crunchbase query:

• US Series B Funding, 2026

Illustration: Dom Guzman

Frequently Asked Questions

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

Venture capital investment is seeing more total money with fewer individual rounds, driven by heavy concentration around artificial intelligence startups.

How much money has been invested in Series B rounds so far in 2026?

Investors have poured approximately $48 billion into Series B stage financings so far this year.

Are smaller Series B rounds becoming more common or scarcer?

Smaller and mid-sized Series B rounds have grown significantly scarcer, with less than a third of deals falling under $30 million this year.

Which companies secured the largest Series B rounds?

Jeff Bezos’ physical AI startup Prometheus secured the largest round at $12 billion, followed by World Labs and Valar Atomics, which each raised $1 billion.

What percentage of Series B funding went to AI startups?

So far this year, about two-thirds of Series B funding has gone to AI-focused startups, representing over half of all reported U.S. Series B deals.