Mach Industries, a defense technology startup, announced it has raised an additional $600 million in a Series C extension round, pushing its valuation to $3.7 billion. This marks a twofold increase in valuation since its initial Series C raise of $300 million at $1.8 billion just three months ago. Investors in both funding rounds include Ribbit Capital, Infinite Capital, Bedrock Capital, and Sequoia.

Founded by 22-year-old Ethan Thornton, Mach Industries develops a range of unmanned military vehicles, including vertical takeoff and landing drones, long-range strike systems, and counter-drone technologies. The company operates a 115,000-square-foot manufacturing facility in Huntington Beach, California, with additional sites across the state.

Mach positions itself as a provider of highly integrated defense systems at lower costs compared to established contractors. In May, it acquired solid rocket motor startup Exquadrum for $50 million in cash and equity, outbidding multiple competitors. This acquisition addresses a shortage of solid rocket motors, a critical component in drone technology, and has led to the creation of Mach Energetics, a new division producing rocket motors, jet engines, and energetic systems.

The startup has attracted significant venture capital interest, including from Sequoia, marking the firm’s first investment in defense technology. Mach also secured a U.S. Army contract earlier this year, further validating its technology and business model. Ribbit Capital, traditionally known for fintech investments, has expanded its portfolio to include defense tech and AI-related startups, reflecting broader investor interest in emerging defense technologies.