U.S. startups closed major funding rounds during the period from August 15 to 21, 2026, with investors showing a clear focus on defense technologies, artificial intelligence and computing-related infrastructure. Castelion topped the list with an $800 million Series C equity financing, in addition to $250 million in debt financing, in a deal led by JPMorgan Chase, Andreessen Horowitz and Carlyle that valued the Torrance, California-based company at approximately $13 billion.
Castelion is developing a hypersonic strike missile, making its round the largest among the deals tracked by the weekly report on disclosed funding rounds for U.S.-based companies.
Artificial Intelligence Attracts Billions of Dollars
Etched ranked second after raising $700 million. The company, based in San Jose, California, develops custom inference clusters to accelerate AI computing, and Jane Street led the round, which raised the four-year-old company’s valuation to $21 billion.
Higgsfield, an AI-powered video and image creation platform, raised $400 million in a Series B round led by DST Global, at a valuation of $5.4 billion for the San Francisco company, whose round included at least 18 investors.
In infrastructure, Groq secured $350 million in a round led by Disruptive, with planned participation from Nvidia. The company operates 13 data centers worldwide and was valued at $3.5 billion after the round, following its raising of $650 million in June.
Wispr Flow also raised $280 million in a Series B round led by Menlo Ventures, bringing its valuation to $2 billion. The company offers an AI-powered speech-to-text tool called Flow. Velaura AI secured $110 million in a Series A round led by Seligman Ventures, giving the startup, which specializes in low-power silicon chips and AI computing infrastructure software, a valuation exceeding $1 billion.
Rounds in Satellites, Mobility and Health
Muon Space, which designs and operates satellite constellations, raised $250 million in a Series C round led by Eclipse. The company had opened a manufacturing facility in San Jose that, according to the article, is capable of producing up to 500 satellites annually by 2027.
Also, a Rivian spinoff specializing in electric bicycles and small four-wheeled mobility vehicles, secured $150 million in a Series D round led by Prysm Capital, with part of the funding directed toward accelerating development of its autonomous vehicle platform.
Rillet, which develops enterprise resource planning tools powered by AI agents, raised $100 million in a Series C round led by Iconiq Capital, at a valuation of $1 billion. This was the company’s third funding round in one year. Happy Health rounded out the list by raising $75 million from Arch Venture Partners and OpenLoop to develop a ring for diagnosing and helping treat sleep apnea.
What Does This Distribution Reflect?
The list shows that capital is flowing simultaneously into AI applications and the layers that support their operation, such as chips, data centers and low-power computing. It also highlights the presence of defense, aerospace, mobility and health, making the list an indicator of the broadening range of sectors benefiting from startup funding, rather than the dominance of a single field. The ranking is based on the largest disclosed rounds in the Crunchbase database for U.S. companies during a single week, with the possibility of limited delays in recording some deals.