The Week’s 10 Biggest Funding Rounds: Defense Tech, AI Tools And Infrastructure Lead The Way

Castelion led the week’s U.S. startup funding with an $800 million Series C plus $250 million in debt at a $13 billion valuation, followed by Etched’s $700 million round at a $21 billion valuation and Higgsfield’s $400 million Series B at $5.4 billion. The top 10 skewed heavily toward AI infrastructure and tools, including Groq’s $350 million raise, Wispr Flow’s $280 million round, and Velaura AI’s $110 million Series A, alongside defense, satellites, micromobility, and enterprise software.

Want to keep track of the largest startup funding deals in 2026 with our curated list of $100 million-plus venture deals to U.S.-based companies? Check out The Crunchbase Megadeals Board . This is a weekly feature that runs down the week’s top 10 announced funding rounds in the U.S. Check out last week’s biggest funding deal roundup here . Startup investors were busily closing on big rounds this week, with AI and defense among their favored target sectors. The biggest financing went to Castelion , a defense tech startup developing a hypersonic missile. Other sizable rounds went to companies developing AI inference technology, a video-creation platform, data centers and voice-to-text tools. 1. Castelion , $800M, defense tech: Castelion, a defense tech startup developing a hypersonic strike missile, raised new Series C funding consisting of $800 million in equity capital along with $250 million in debt financing. JPMorgan Chase , Andreessen Horowitz and Carlyle led the equity financing, which set a $13 billion valuation for the Torrance, California-based company. 2. Etched , $700M, semiconductors: San Jose, California-based Etched, a developer of inference clusters to accelerate AI computing, secured $700 million in a new funding round led by Jane Street and joined by a long list of prominent investors. The financing set a $21 billion valuation for the 4-year-old company. 3. Higgsfield , $400M, AI video tools: AI video- and image-creation platform Higgsfield closed on $400 million in Series B financing at a $5.4 billion valuation. DST Global led the round for the San Francisco-based company, with the financing drawing at least 18 investors. 4. Groq , $350M, data centers: Groq, an operator of 13 data centers across the globe, pulled in $350 million in a new fundraise led by Disruptive , with planned participation from Nvidia .The fundraise, which values the San Francisco-based company at $3.5 billion, comes on the heels of a $650 million round in June. 5. Wispr Flow , $280M, voice-to-text AI: Wispr Flow, a provider of an AI-powered voice-to-text tool called Flow, picked up $280 million in Series B funding at a $2 billion valuation. Menlo Ventures led the financing, joined by a long list of new and existing investors. 6. Muon Space , $250M, satellites: Muon Space, a designer, builder and operator of satellite constellations, closed on $250 million in Series C funding led by Eclipse . The Mountain View, California-based company also recently opened a manufacturing facility in San Jose, California, designed to produce up to 500 satellites annually by 2027. 7. Also , $150M, micromobility: Also, a Rivian spinout that makes electric bikes and small four-wheeled micromobility vehicles, secured $150 million in Series D funding led by Prysm Capital . The Palo Alto, California-based startup said the financing will go in part toward accelerating development of its autonomous vehicle platform. 8. Velaura AI , $110M, AI computing: Velaura AI, a developer of AI compute infrastructure focused on ultra-low-power silicon and software technologies, picked up $110 million in Series A funding. Seligman Ventures led the financing, which set a valuation of over $1 billion for the Silicon Valley-based startup. 9. Rillet , $100M, agentic finance: Rillet, a developer of AI-powered enterprise resource planning tools, landed $100 million in Series C funding led by Iconiq Capital . The round, which sets a $1 billion valuation for the San Francisco company, is Rillet’s third financing in the past year. 10. Happy Health , $75M, sleep testing: Happy Health, and Austin-based developer of a ring device for diagnosis and treatment of sleep apnea, raised $75 million from Arch Venture Partners and OpenLoop . Methodology We tracked the largest announced rounds in the Crunchbase database that were raised by U.S.-based companies for the period of Aug. 15-21. Although most announced rounds are in the database, there may be a small time lag, as some rounds are reported late in the week. Illustration: Dom Guzman