U.S. Series B Funding Concentrates on Large AI Deals
Crunchbase data shows total U.S. Series B investment has reached $48 billion this year, even as the number of deals continues to decline.
Investment activity in the U.S. Series B market is undergoing a shift, with capital concentrating heavily on a small group of artificial intelligence companies. While total funding for the year has reached approximately $48 billion—the highest level in several years—the total count of completed funding rounds is trending toward a multi-year low.
A primary driver of this trend is the decline in small and mid-sized rounds. Deals under $30 million now account for less than one-third of total activity, compared to approximately 50% between 2021 and 2025. Conversely, larger funding rounds of $100 million or more represent roughly a quarter of all deals, with firms like Prometheus and World Labs securing significant capital this year.
Approximately two-thirds of all Series B funding has been directed toward AI-focused startups. While the environment remains bullish for established AI ventures with proven traction, the market for smaller Series B rounds remains constrained. Investors are increasingly prioritizing large checks for high-valuation companies, leaving fewer opportunities for smaller market participants.