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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 rounds here.

There may have been fewer nine-figure rounds this week, but the ones we did have were massive. Energy and data centers seem to be on everyone’s mind right now — and this week’s list bears that out.

1. X-energy, $500M, energy: A big raise from the nuclear reactor and fuel space this week. Rockville, Maryland-based X-energy raised a Series C-1 of approximately $500 million, anchored by Amazon. The company is developing advanced small modular nuclear reactors for clean energy generation. Amazon and X-energy are collaborating to bring more than 5 gigawatts of new power projects online across the United States by 2039. Founded in 2009, the company has raised more than $785 million, per Crunchbase.

2. Lightmatter, $400M, data centers: Lightmatter, a startup that uses light to link chips together and to do calculations for the deep learning necessary for AI, locked up a $400 million Series D led by new investor T. Rowe Price at a $4.4 billion valuation. The new round nearly quadruples its previous valuation of $1.2 billion in December after a $155 million raise led by GV — which along with Fidelity Management and Research Co. also participated in the new round. As Big Tech pours hundreds of billions of dollars into new AI data centers, Lightmatter is trying to solve the problems around energy consumption and scalability of those new centers. The company’s tech uses silicon photonics that can speed up processes while also using less power. Although the idea of using light in computing isn’t new, creating the components has historically been challenging. Founded in 2017, Lightmatter has raised $850 million, per the company. Lightmatter’s was not the only large raise by a photonic startup this week. Xscape Photonics — a New York-based startup also using photonics technology to address the energy, performance and scalability challenges of AI data centers — raised a $44 million Series A led by IAG Capital Partners with investment from the likes of Cisco Investments and Nvidia.

3. Splitero, $300M, fintech: Part of the beauty of being a homeowner is having equity in that home. Unfortunately, accessing that equity can sometimes be burdensome. San Diego-based Splitero offers homeowners another option to do just that and this week the startup locked up $300 million through a strategic investment from funds managed by Antarctica Capital to further that mission. Splitero offers homeowners a lump sum of cash in exchange for a share of their home’s future value. Founded in 2021, the company has raised nearly $318 million, per Crunchbase.

4. Terray Therapeutics, $120M, biotech: Los Angeles-based Terray Therapeutics, a biotech startup developing small molecule drug therapeutics, raised a $120 million Series B led by new investor Bedford Ridge Capital and existing investor NVentures. Founded in 2018, the company has raised $200 million, per Crunchbase.

5. Path Robotics, $100M, robotics: Path Robotics, a startup using AI in robotic welding systems in the manufacturing industry, announced it has closed $100 million in new investments in the past year led by Drive Capital and Matter Venture Partners. The Columbus, Ohio-based company currently has two robotic welding products in the market, both leveraging vision systems, artificial intelligence and machine learning to autonomously weld steel parts. Founded in 2018, Path has raised $170 million, per the company.

6. Skimmer, $74M, service industry: Austin, Texas-based Skimmer, a software provider for pool service businesses, raised $74 million in growth capital from Mainsail Partners. Founded in 2014, the company has raised $79 million, per Crunchbase.

7. Decagon, $65M, artificial intelligence: San Francisco-based company Decagon, a developer of AI customer support agents, raised a  $65 million Series B led by Bain Capital Ventures. Founded in 2023, Decagon has raised $100 million, per the company.

8. Oshi Health, $60M, health care: New York-based Oshi Health, a virtual gastrointestinal care startup, raised a $60 million Series C funding led by Oak HC/FT. Founded in 2019, the company has raised nearly $120 million, per Crunchbase.

9. Koloma, $50M, energy: Denver-based Koloma, which identifies and commercializes geologic hydrogen resources, reportedly raised a $50 million Series B extension led by Osaka Gas and Mitsubishi Heavy Industries. Founded in 2021, the company has raised more than $386 million, per Crunchbase.

10. Galileo, $45M, artificial intelligence: Galileo, which provides generative AI evaluation and observability for enterprises, raised a $45 million Series B led by Scale Venture Partners. Founded in 2021, the San Francisco-based company has raised more than $68 million, per Crunchbase.

Big global deals

The biggest deal of the week outside the U.S. came from north of the border.

• Montreal-based Blockstream, a blockchain developer of digital asset infrastructure, raised $210 million in convertible note funding.

Methodology

We tracked the largest announced rounds in the Crunchbase database that were raised by U.S.-based companies for the seven-day period of Oct. 12 to Oct. 18. Although most announced rounds are represented in the database, there could be a small time lag as some rounds are reported late in the week.

Illustration: Dom Guzman