The 10 Largest US Funding Rounds of December 2025 – AlleyWatch

Armed with some data from our friends at CrunchBase, I broke down the largest US startup funding rounds from December 2025. I have included some additional information such as industry, company description, round type, founders, and total equity funding raised to further the analysis.

10. HawkEye 360 $150.0MRound: Series EDescription: Herndon-based HawkEye 360 detects, geolocates, and characterizes various RF signals using its satellite constellation in low Earth orbit. Founded by Charles Clancy, Chris DeMay, John Serafini, and Robert McGwier in 2015, HawkEye 360 has now raised a total of $522.3M in total equity funding and is backed by Insight Partners, Alumni Ventures, BlackRock, Lockheed Martin Ventures, and Adage Capital Management.Investors in the round: Andreessen Horowitz, BlackRock, Blackstone Group, Coatue, Fidelity, GIC, Infinitum, Insight Partners, J.P. Morgan Asset Management, MGX, New Enterprise Associates, Ontario Teachers’ Pension Plan, Robinhood Ventures, Temasek Holdings, Thrive Capital, T. Rowe Price, Winslow CapitalIndustry: Aerospace, Analytics, Artificial Intelligence (AI), Navigation, Satellite Communication, WirelessFounders: Charles Clancy, Chris DeMay, John Serafini, Robert McGwierFounding year: 2015Total equity funding raised: $522.3M

9. Harness $200.0MRound: Series EDescription: San Francisco-based Harness provides a software delivery platform that helps engineering teams build, deploy, and operate applications through a set of tools. Founded by Jyoti Bansal and Rishi Singh in 2017, Harness has now raised a total of $570.0M in total equity funding and is backed by Menlo Ventures, Gaingels, IVP, Norwest, and Battery Ventures.Investors in the round: Carrick Capital Partners, Kohlberg Kravis Roberts, Sixth Street Growth, Ten Eleven VenturesIndustry: Artificial Intelligence (AI), Developer Tools, DevOps, Productivity Tools, SaaSFounders: Jyoti Bansal, Rishi SinghFounding year: 2017Total equity funding raised: $570.0M

8. Tebra $250.0MRound: VentureDescription: Corona Del Mar-based Tebra provide independent healthcare practices with digital tools and support to thrive in a new era of healthcare. Founded by Dan Rodrigues, Luke Kervin, and Travis Schneider in 2021, Tebra has now raised a total of $387.0M in total equity funding and is backed by Vivo Capital, JP Morgan, StepStone Group, Transformation Capital, and Hildred Capital.Investors in the round: Altimeter Capital, Andreessen Horowitz, Avenir Group, BlueYard Capital, Cantos, Champion Hill Ventures, First In, General Catalyst, Interlagos Capital, Lavrock Ventures, Lightspeed Venture Partners, Silent Ventures, Space.VC, Valor Equity PartnersIndustry: Electronic Health Record (EHR), Health Care, MedicalFounders: Dan Rodrigues, Luke Kervin, Travis SchneiderFounding year: 2021Total equity funding raised: $387.0M

8. K2 Space $250.0MRound: Series CDescription: Torrance-based K2 Space develops high-power satellite platforms for orbital missions, using vertically integrated hardware and manufacturing processes. Founded by Karan Kunjur and Neel Kunjur in 2022, K2 Space has now raised a total of $425.5M in total equity funding and is backed by Lightspeed Venture Partners, Redpoint, Altimeter Capital, Alpine Space Ventures, and First Round Capital.Investors in the round: Accel, Atlassian Ventures, CapitalG, Creandum, Databricks Ventures, DST Global, EQT Growth, Evantic Capital, HubSpot Ventures, Khosla Ventures, Kinship Ventures, Menlo Ventures, NVentures, Salesforce Ventures, T.CapitalIndustry: Aerospace, Machinery Manufacturing, Manufacturing, Space TravelFounders: Karan Kunjur, Neel KunjurFounding year: 2022Total equity funding raised: $425.5M

7. Boom Supersonic $300.0MRound: Series BDescription: Centennial-based Boom Supersonic is a commercial airplane manufacturer that builds supersonic airliners designed for speed, safety, and sustainability. Founded by Blake Scholl, Joe Wilding, and Joshua Krall in 2014, Boom Supersonic has now raised a total of $647.5M in total equity funding and is backed by Bessemer Venture Partners, Caffeinated Capital, 8VC, Y Combinator, and Karman Ventures.Investors in the round: Altimeter Capital, ARK Investment Management, Bessemer Venture Partners, Darsana Capital Partners, Robinhood Ventures, Y CombinatorIndustry: Aerospace, Air Transportation, ManufacturingFounders: Blake Scholl, Joe Wilding, Joshua KrallFounding year: 2014Total equity funding raised: $647.5M

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7. Radiant $300.0MRound: Series DDescription: El Segundo-based Radiant develops portable nuclear microreactors designed to generate electricity and heat in a compact, factory-built form. Founded by Bob Urberger and Doug Bernauer in 2019, Radiant has now raised a total of $518.8M in total equity funding and is backed by Andreessen Horowitz, Tribe Capital, Draper Associates, Alumni Ventures, and Union Square Ventures.Investors in the round: Align Ventures, Andreessen Horowitz, ARK Venture Fund, Boost VC, Chevron Technology Ventures, DCVC, Draper Associates, Founders Fund, Friends & Family Capital, Giant Ventures, IQT, Sahin Boydas, StepStone Group, Union Square Ventures, Washington Harbour PartnersIndustry: Clean Energy, Energy, Energy Efficiency, Renewable EnergyFounders: Bob Urberger, Doug BernauerFounding year: 2019Total equity funding raised: $518.8M

7. Eon $300.0MRound: Series DDescription: New York-based Eon is a cloud backup posture management platform that provides instant access to all backed-up cloud data. Founded by Gonen Stein, Ofir Ehrlich, and Ron Kimchi in 2024, Eon has now raised a total of $497.0M in total equity funding and is backed by Lightspeed Venture Partners, Sequoia Capital, Bond, Affinity Partners, and Greenoaks.Investors in the round: Center15 Capital, NightDragon, Principia Growth, Trajectory VenturesIndustry: Cloud Data Services, Cloud Management, Data Management, SaaSFounders: Gonen Stein, Ofir Ehrlich, Ron KimchiFounding year: 2024Total equity funding raised: $497.0M

6. Lovable $330.0MRound: Series BDescription: Dover-based Lovable provides an AI-driven platform enabling users to generate and deploy web applications and websites from natural language prompts. Founded by Anton Osika and Fabian Hedin in 2023, Lovable has now raised a total of $552.5M in total equity funding and is backed by Menlo Ventures, Accel, Khosla Ventures, Creandum, and Antler.Investors in the round: Hildred Capital, HLM Venture Partners, Toba Capital, Transformation CapitalIndustry: Artificial Intelligence (AI), Developer Platform, Developer Tools, SoftwareFounders: Anton Osika, Fabian HedinFounding year: 2023Total equity funding raised: $552.5M

5. Castelion $350.0MRound: Series BDescription: Torrance-based Castelion is a defense tech company that applies modern hardware development and manufacturing processes to national security challenges. Founded by Andrew Kreitz, Bryon Hargis, and Sean Pitt in 2022, Castelion has now raised a total of $439.6M in total equity funding and is backed by Andreessen Horowitz, General Catalyst, Lightspeed Venture Partners, Valor Equity Partners, and Cantos.Investors in the round: Affinity Partners, Bond, Gil Capital, Greenoaks, Lightspeed Venture Partners, Omri Casspi, Sequoia Capital, Swish Ventures, Vine VenturesIndustry: Aerospace, Government, Manufacturing, Military, National SecurityFounders: Andrew Kreitz, Bryon Hargis, Sean PittFounding year: 2022Total equity funding raised: $439.6M

5. Erebor $350.0MRound: VentureDescription: Columbus-based Erebor is a nationally chartered bank designed for the new innovation economy. Founded by Owen Rapaport in 2025, Erebor has now raised a total of $350.0M in total equity funding and is backed by Lux Capital, 8VC, Founders Fund, and Haun Ventures.Investors in the round: AllianceBernstein, Atacama Ventures, B Capital, Breakthrough Energy Ventures, CalSTRS, Capricorn Investment Group, Carbon Equity, Centaurus Capital, Climate First, Congruent Ventures, CPP Investments, DCVC, Devon Energy Corporation, Echelon, Galvanize, Google, Impact Science Ventures, JB Straubel, Kris Singh, Liberty Mutual Investments, Marunouchi Innovation Partners, Mercuria, Mitsubishi Heavy Industries, Mitsui & Co, Sabanci Climate TechnologiesIndustry: Banking, Blockchain, Finance, Financial Services, FinTechFounders: Owen RapaportFounding year: 2025Total equity funding raised: $350.0M

4. Fervo Energy $462.0MRound: Series EDescription: Houston-based Fervo Energy develops and operates clean energy technology to generate carbon-free energy from geothermal systems. Founded by Jack Norbeck and Tim Latimer in 2017, Fervo Energy has now raised a total of $1.1B in total equity funding and is backed by B Capital, DCVC, Mercuria, Galvanize Climate Solutions, and Galvanize.Investors in the round: Goldman SachsIndustry: Energy, Energy Efficiency, Energy Management, Nuclear, Renewable EnergyFounders: Jack Norbeck, Tim LatimerFounding year: 2017Total equity funding raised: $1.1B

3. Unconventional AI $475.0MRound: SeedDescription: San Francisco-based Unconventional AI rethinks computer foundations to optimize energy efficiency for AI. Founded by Naveen Rao, Michael Carbin, Sara Achour,MeeLan Lee in 2025, Unconventional AI has now raised a total of $475.0M in total equity funding and is backed by Andreessen Horowitz, Sequoia Capital, Lightspeed Venture Partners, Databricks, and Lux Capital.Investors in the round: Alpine Space Ventures, Altimeter Capital, Hedosophia, Lightspeed Venture Partners, Redpoint, T. Rowe PriceIndustry: Artificial Intelligence (AI), Business Intelligence, SoftwareFounders: Naveen Rao, Michael Carbin, Sara Achour,MeeLan LeeFounding year: 2025Total equity funding raised: $475.0M

2. Saviynt $700.0MRound: Series BDescription: El Segundo-based Saviynt offers an AI-based identity security platform that secures and governs all types of identities across digital ecosystems. Founded by Amit Saha, Atul Vij, and Sachin Nayyar in 2010, Saviynt has now raised a total of $870.0M in total equity funding and is backed by HPS Investment Partners, PNC Bank, Ten Eleven Ventures, Kohlberg Kravis Roberts, and Carrick Capital Partners.Investors in the round: 8VC, Founders Fund, Haun Ventures, Lux CapitalIndustry: Artificial Intelligence (AI), Cloud Data Services, Cyber Security, Enterprise SoftwareFounders: Amit Saha, Atul Vij, Sachin NayyarFounding year: 2010Total equity funding raised: $870.0M

1. Databricks $4.0BRound: VentureDescription: San Francisco-based Databricks is a data and AI platform that unifies data engineering, analytics, and machine learning on a lakehouse architecture. Founded by Ali Ghodsi, Andy Konwinski, Arsalan Tavakoli-Shiraji, Ion Stoica, Matei Zaharia, Patrick Wendell, and Reynold Xin in 2013, Databricks has now raised a total of $20.6B in total equity funding and is backed by Andreessen Horowitz, Blue Owl, Gaingels, NVIDIA, and Temasek Holdings.Investors in the round: Andreessen Horowitz, Databricks, DCVC, Era, Future Ventures, Jeff Bezos, Lightspeed Venture Partners, Lux Capital, Naveen Rao, Sequoia CapitalIndustry: Analytics, Artificial Intelligence (AI), Data Storage, Information Technology, Machine LearningFounders: Ali Ghodsi, Andy Konwinski, Arsalan Tavakoli-Shiraji, Ion Stoica, Matei Zaharia, Patrick Wendell, Reynold XinFounding year: 2013Total equity funding raised: $20.6B