April 2026’s Biggest US Startup Rounds: $10B Prometheus tops an AI-heavy month
April 2026 delivered a flood of capital to US startups, capped by one of the largest single startup rounds ever recorded: $10 billion for Project Prometheus, Jeff Bezos’s bet on AI for the physical economy.
The month’s top deals underscored investor appetite for technologies that link artificial intelligence to real-world systems — spanning nuclear energy to autonomous flight to rare-earth manufacturing — alongside fresh momentum in fintech and health coverage tools.
Among the larger rounds, Sunnyvale-based Scout AI raised a Series A to advance AI systems for defense robotics, focused on autonomous behavior across unmanned platforms. Founded in 2024 by Colby Adcock and Collin Otis, the company operates at the intersection of aerospace, AI, and manufacturing.
Investors in the round included Align Ventures, Booz Allen Ventures, Bravo Victor Venture Capital, Decisive Point, Disruptive Founders Fund, Draper Associates, Evolution VC Partners, FJ Labs, Heraclitus Capital Management, Monte Carlo Capital, Neman Ventures, Shane Neman, Sigmas Group, and Vaughn Capital Partners.
Scout AI has raised $115.2 million in total equity funding and is backed by Gaingels, Draper Associates, Booz Allen Ventures, FJ Labs, and Decisive Point. Palo Alto-based Parallel, founded in 2023 by Parag Agrawal, closed a Series B to develop agents and tool APIs that allow AI to access and use the open web.
Investors in the round included Index Ventures, Khosla Ventures, Kleiner Perkins, and Sequoia Capital. Parallel has raised $260 million in total equity funding across artificial intelligence, developer APIs, and information technology. San Francisco-based Slash extended the fintech surge with a Series C for its platform that unifies businesses’ financial operations.
Founded in 2020 by Kevin Bai and Victor Cardenas, Slash is backed by Goodwater Capital, Khosla Ventures, Ribbit Capital, and Y Combinator in this round. The company, which operates across banking, financial services, fintech, and payments, has raised $160 million in total equity funding.
In health tech, New York-based Chapter secured a Series E for its Medicare navigation platform that provides advisory services to seniors seeking coverage. Founded in 2013 by Cobi Blumenfeld-Gantz, Corey Metzman, and Vivek Ramaswamy, the round drew participation from 8VC, Addition, Fifth Down Capital, Generation Investment Management, Maverick Ventures, Narya Capital, Stripes, Susa Ventures, and XYZ Venture Capital.
Chapter has raised $284 million in total equity funding. San Mateo-based Netomi advanced its enterprise-focused generative AI with a Series C. Founded by Puneet Mehta in 2015 and backed by BoxGroup, Y Combinator, Index Ventures, WndrCo, and Salesforce Ventures, the company builds software for customer service and broader enterprise use cases across AI, machine learning, SaaS, and digital marketing.
Netomi has raised $217 million in total equity funding. Autonomous flight also featured prominently. Skydio, the San Mateo drone maker founded in 2014 by Abraham Bachrach, Adam Bry, and Matt Donahoe, completed a Series F as it scales AI-powered flying drones for consumer, enterprise, and government customers.
The company has raised $850 million in total equity funding. Taken together, April’s top US financings spotlight where the heaviest checks are landing: AI systems tied to physical-world operations, next-generation developer tools, financial infrastructure, and health coverage platforms — alongside advances in sectors such as autonomous flight.
The scale of these rounds, led by Project Prometheus’s $10 billion financing, suggests investors are concentrating capital in companies building foundational capabilities for the physical and digital economies.