NeuralStackTemporal Technologies led the latest wave of major U.S. startup financings with a $550 million Series E, according to a Crunchbase review of announced rounds from Sept. 12-18, 2026. The Bellevue, Washington-based company was valued at $12.55 billion in the financing, which was led by Lightspeed, Wellington Management, Goldman Sachs Alternatives and Tiger Global.
Temporal develops an open source platform for building and operating long-running AI agents and other enterprise systems. Its position at the top of the list reflects the continuing appetite for technology designed to support AI applications beyond the model layer.
Impulse Space ranked second after securing $308 million in a Series D extension. The Redondo Beach, California-based developer of space vehicles for moving payloads across and between orbits said the financing brought the combined round total to $808 million.
Ridgeline was the third-largest recipient, raising $250 million in Series E funding for its AI-enabled investment management platform. The round, led by founder and chairman Dave Duffield, valued the Incline Village, Nevada-based company at $1.45 billion.
The rest of the leading rounds also pointed toward specialized infrastructure and software. 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.
AI-focused marketing startup Profound raised $180 million in Series D funding at a $1.8 billion valuation, with Sequoia Capital and Kleiner Perkins leading the round. Arcee AI, which develops open-weight AI models, secured $150 million in Series B funding at a valuation above $1 billion.
Why this matters
The funding mix suggests that investors are backing the infrastructure, workflow and specialized applications needed to make AI useful across industries. The week’s largest deals were smaller than the multiple billion-dollar rounds seen previously, but they still concentrated heavily in AI infrastructure, networking, software development, marketing and investment management.
Three additional companies rounded out the list. Gaming company Nex secured $150 million in equity and debt financing, including a Series E led by Baillie Gifford and BAI Capital; geothermal developer Mazama Energy raised $135 million in Series B funding; and biotech company Sling Therapeutics closed a $123 million Series C for its small-molecule therapy for thyroid eye disease.
Crusoe also made official its previously reported raise of more than $3 billion, co-led by Atreides Management, Valor Equity Partners and Mubadala Capital, although that financing was not included among the 10 rounds ranked for the week. Crunchbase noted that its list tracks announced rounds by U.S.-based companies and may not capture deals reported late.