Mach Industries Doubles to $3.7 Billion Valuation in Three Months

Mach Industries raised $600 million in a Series C extension this month at a $3.7 billion valuation — more than double the $1.8 billion the defense tech firm fetched just three months earlier.

The initial $300 million Series C closed in June 2026, led by Ribbit Capital, Infinite Capital, Bedrock Capital, and Sequoia Capital. The speed of the repricing is striking. So is the age of the person running the company.

Founder and CEO Ethan Thornton launched Mach in 2023 at 19, after developing an interest in defense as a teenager. He is now 22 and runs a company with six weapons programs, a 115,000-square-foot headquarters and manufacturing facility in Huntington Beach, California, and ambitions to build everything from airframes and jet engines to solid rocket motors, energetic systems, and autonomous technologies.

"You're never going to know everything, especially when you're starting young, and you shouldn't expect to," Thornton told Fortune. "If you wait until you have all the answers, you'll probably never start."

From Home Depot prototypes to an Army deal

Thornton grew up in a military family in Texas. By 16, he was prototyping defense applications on his parents' property, experimenting with hydrogen-powered weapons using materials sourced from Home Depot and Amazon. He described his motivation as concern about China's rise and an "impending great power conflict."

He took that interest to MIT, where he studied aerospace and worked with the school's federally funded defense research center, Lincoln Laboratory. Before finishing his first year, he received a Thiel Fellowship and left MIT to focus on his company full-time.

Silicon Valley moved fast. In June 2023, Sequoia Capital led a $5.7 million round in Mach — the firm's first investment in a hardware defense technology company. "Ethan is a force of nature: from his technical depth and genuine obsession with the problem to his bias for action and maturity beyond his years," Sequoia partner Stephanie Zhan, who led the investment, said at the time. "Defense technology is central to our safety and security, and Mach is a step-function advancement to the state of the industry."

By 2024, Mach had landed a deal with the Army Applications Laboratory to develop a vertical-takeoff precision cruise missile.

Riding — and outpacing — a defense funding boom

Mach's growth comes amid a broader boom in defense tech. A record $19.8 billion was deployed into the sector in the first quarter of 2026 alone, Fortune reported. Thornton is betting his company can do more than ride that wave. After several years developing and testing its technology, Mach is now shifting its focus toward production.

"For a company like Mach, private capital lets us take risk earlier. We can build before there's a massive program behind something, test it, learn from it and change it quickly," Thornton told Fortune. "And because we think about manufacturing from the beginning, we're not designing something and figuring out how to produce it years later. We're building the product and the production capability at the same time."

Thornton credits much of his trajectory to the people around him. "Find people who are better than you at the things you don't know, who will challenge you and who believe in what you're trying to build," he said. His advice to other young founders: "You have to be willing to learn as you go, make mistakes and keep moving. Have conviction in the problem you're trying to solve, and then surround yourself with people who can help you solve it."

With $900 million raised across two rounds in a single quarter and a pivot from prototyping to manufacturing, Mach now faces its toughest test: converting investor confidence in a 22-year-old's vision into weapons systems produced at scale.