NeuralStackAI and energy dominated a busy week for large U.S. startup funding rounds, with investors backing companies involved in infrastructure, models, quantum computing, content protection and power systems. The largest financing went to Axiom Solutions International, a private cloud and power infrastructure company spun out of manufacturing services provider Flex.
Axiom secured $2 billion through a strategic investment from General Catalyst and Koch Equity, which purchased shares in the Austin-based company from Flex at an initial enterprise value of $37.5 billion. Flex said it plans to separate Axiom into an independent publicly traded company early next year.
TypeSafe AI ranked second with $870 million in new funding. The San Francisco-based company develops Jev, a recently launched AI model with a growing early following, and the round reportedly valued the company at $7.5 billion. Andreessen Horowitz was the largest investor, while Sequoia Capital also participated, according to a Bloomberg report.
Oratomic raised $475 million for its work on fault-tolerant quantum computers. The Pasadena, California-based startup’s financing was led by Arch Venture Partners, Spark Capital, Khosla Ventures, Index Ventures, General Catalyst and Bezos Expeditions, following a $300 million financing in July.
SignSplit also emerged from stealth with a major financing, raising $400 million in seed funding at a $1 billion valuation. The New York-based company, founded in 2024, develops tools for protecting, licensing and contributing real-world human data and other forms of human contribution.
Other notable rounds reflected the breadth of the funding surge. Vinci raised $250 million in Series B funding at a $1.5 billion valuation for its AI computational platform for hardware engineers, while Atomic Machines said it had raised $250 million to date for AI-native digital manufacturing systems designed to build micro-machines directly from code.
Energy companies also attracted substantial capital. Voltus raised $225 million in Series D funding for its distributed energy platform, while Type One Energy secured $200 million in Series B financing for fusion energy technology. Ledgebrook, an AI-powered specialty insurance platform, and Arena, an AI-model evaluation company, each raised $200 million; Arena said its annual revenue run rate had exceeded $100 million and that the financing valued it at $3.1 billion.
Why this matters
The distribution of the rounds shows that AI investment is extending beyond model developers into the physical and commercial systems that support adoption. Cloud and power infrastructure, hardware engineering, manufacturing, data protection and model evaluation all appeared alongside foundational AI, suggesting that investors are funding a broader technology stack rather than a single category.
The list also underscores the overlap between AI and energy. Axiom’s cloud and power infrastructure focus, Voltus’ grid-flexibility platform and Type One Energy’s fusion work target the infrastructure challenges associated with expanding computation and electricity demand. The companies’ next steps will show whether this concentrated financing can translate into deployable systems, durable businesses and public-market readiness.
Crunchbase compiled the list from the largest announced rounds raised by U.S.-based companies during Oct. 3-9, 2026. The database may contain a small time lag because some financing announcements are reported late in the week.