SA国际传媒

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 SA国际传媒 Megadeals Board.

This is a weekly feature that runs down the week鈥檚 Top 10 announced funding rounds in the U.S. Check out last week鈥檚 biggest funding deal roundup here.

After a week of multiple billion-dollar-plus rounds, startup investors have reduced the number of zeroes on their funding checks. This past week, the largest U.S. startup funding rounds were in the hundreds of millions, topped by a $550 million financing for AI infrastructure company and a $308 million investment in space vehicle developer .

The remaining list of big rounds featured mostly AI-focused companies in sectors including investment management, networking, coding and marketing as well as some energy and biotech. Data center developer , also made official its previously reported $3 billion-plus raise, co-led by , and .

1. , $550M, AI infrastructure: Temporal Technologies, developer of an open source platform for building and operating long-running AI agents and other enterprise systems, secured $550 million in Series E funding at a $12.55 billion valuation. , , , and led the financing for the Bellevue, Washington-based company.

2. , $308M, space tech: Redondo Beach, California-based Impulse Space, a developer of space vehicles for moving payloads across and between orbits, secured $308 million in Series D extension funding. The financing brings the combined round total to $808 million.

3. , $250M, investment management: Ridgeline, an AI-enabled investment management platform, picked up $250 million in a Series E funding round. The financing, led by founder and chairman , set a $1.45 billion valuation for the Incline Village, Nevada-based company.

4. , $205M, networking: Wayne, Pennsylvania-based Cornelis Networks, a developer of networking technology for AI and high-performance computing workloads, closed on $205 million in new funding backed by .

5. , $200M, AI software development: San Francisco-based Factory, a provider of AI tools for enterprise software development, announced a $200 million funding round at a $5 billion valuation, backed by a long list of venture firms and individual investors.

6. , $180M, AI marketing: Profound, a startup offering marketing software to help users appear more prominently in AI results, raised $180 million in Series D funding at a $1.8 billion valuation. and led the financing for the New York-based company.

7. (tied) , $150M, foundational AI: Arcee AI, a developer of open-weight AI models, closed on $150 million in Series B funding at a valuation of more than $1 billion. , and led the round for the San Francisco-based company.

7. (tied) , $150M, gaming: Nex, a developer of family-oriented digital games that rely on body motion rather than controllers, secured $150 million in new equity and debt financing, including a Series E led by and . The San Francisco company did not break out how much of the round consisted of equity.

9. , $135M, geothermal energy: Mazama Energy, a Seattle-based geothermal energy developer specializing in superhot rock geothermal power, picked up $135 million in a Series B round led by and .

10. , $123M, biotech: Sling Therapeutics, developer of a small-molecule therapy for thyroid eye disease, closed on $123 million in Series C funding. led the financing for the Ann Arbor, Michigan-based company.

Methodology

We tracked the largest announced rounds in the SA国际传媒 database that were raised by U.S.-based companies for the period of Sept. 12-18, 2026. Although most announced rounds are in the database, there may be a small time lag, as some rounds are reported late in the week.

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