NeuralStackTemporal Technologies topped the latest ranking of large U.S. startup financings with a $550 million Series E that valued the AI infrastructure company at $12.55 billion. Lightspeed, Wellington Management, Goldman Sachs Alternatives and Tiger Global led the round. Based in Bellevue, Washington, Temporal develops an open source platform for building and operating long-running AI agents and other enterprise systems.
Impulse Space placed second with a $308 million Series D extension, bringing the combined round total to $808 million. The Redondo Beach, California-based company develops space vehicles designed to move payloads across and between orbits. Its financing was the largest non-AI round among the week’s top two deals.
Investment management platform Ridgeline secured $250 million in Series E funding at a $1.45 billion valuation. Founder and chairman Dave Duffield led the financing for the Incline Village, Nevada-based company, whose platform uses AI in investment management.
Several other rounds focused on the infrastructure and software layers supporting AI. Cornelis Networks raised $205 million for networking technology aimed at AI and high-performance computing workloads, while Factory announced $200 million at a $5 billion valuation for its enterprise software-development tools. Profound added $180 million in Series D funding at a $1.8 billion valuation for marketing software intended to help users appear more prominently in AI results.
The remaining deals showed that the funding surge was not limited to enterprise AI. Arcee AI raised $150 million in Series B funding at a valuation above $1 billion for its open-weight AI models, and Nex secured $150 million in equity and debt financing for family-oriented digital games controlled through body motion rather than traditional controllers.
Energy and biotech rounded out the ranking. Mazama Energy raised $135 million in Series B funding for its superhot rock geothermal power business, while Sling Therapeutics closed a $123 million Series C for a small-molecule therapy targeting thyroid eye disease.
Why this matters
The week’s funding pattern points to a broadening AI investment market. Capital went not only to foundational models, but also to agent infrastructure, networking, enterprise development tools and marketing systems built around AI-generated results. That distribution suggests investors are backing the operational layers required to turn AI capabilities into business software.
The ranking also reflects continued appetite for capital-intensive technology outside mainstream software. Impulse Space’s financing highlights demand for orbital transportation, while Mazama Energy’s round puts substantial venture funding behind an emerging geothermal approach. At the same time, Ridgeline’s valuation shows that AI applications in established financial workflows remain a significant target for growth capital.
Crunchbase tracked the largest announced rounds raised by U.S.-based companies from Sept. 12 through Sept. 18, 2026. The publication noted that announced rounds can appear in its database with a small delay, so the ranking may not capture every financing immediately when it is announced.