Jeff Lawson built Twilio into a $48 billion company, stepped back as CEO, and then decided to go after something harder. In February 2026, Inertia Enterprises – the fusion energy startup Lawson co-founded in 2024 – raised $450 million in Series A financing, according to TechCrunch. The round was led by Bessemer Venture Partners with participation from Alphabet’s GV, Modern Capital, and Threshold Ventures. It is among the largest early-stage energy startup rounds in recent history.
Inertia’s mission: commercialize the same laser-based fusion physics proven at Lawrence Livermore National Laboratory – specifically the December 2022 experiment that achieved net target energy gain for the first time. The company’s leadership team includes Dr. Annie Kritcher, who designed that NIF experiment, and Prof. Mike Dunne, former director of Stanford’s SLAC research facility. These are not outsiders making bold claims. They built the science that proved it could work.
What This Actually Means
Lawson left Twilio in 2023 after leading it from a two-person API startup to a publicly traded giant serving 300,000 businesses. Most founders at that stage take a board seat or spend a year at a beach. Lawson co-founded a fusion energy company.
What’s instructive for any entrepreneur watching this: Inertia isn’t speculating on unproven science. The company’s strategy is explicitly to build on validated physics rather than try to prove something new. They’re betting that the bottleneck is now engineering and capital, not the fundamental science. That’s a very different risk profile than most deep-tech bets, and it’s exactly the kind of framing that gets Bessemer to write a $450 million check at the Series A stage.
Inertia’s fusion approach – called Thunderwall – centers on a laser beamline designed to deliver 10 kilojoules of energy 10 times per second at 10% wall-plug efficiency. The company says Thunderwall would be 50 times as powerful in average power as any prior laser of its type. If you’ve followed how the biggest breakout companies clear the “you’re crazy” bar, Inertia follows the same pattern: proven science, elite team, and enough capital to make execution the only real question.
The Numbers Behind It
Inertia’s raise landed in a venture market that is surging. According to Crunchbase, U.S. startup funding hit $87 billion in Q1 2026 – the strongest quarter since 2021. Energy and climate tech have claimed a growing share of that capital as institutional investors shift toward sectors where AI and clean energy converge.
The U.S. Department of Energy has invested over $3.5 billion in the National Ignition Facility alone. Private capital is now trying to commercialize what public science unlocked – a pattern we’ve seen before in biotech and aerospace. Inertia is explicitly trying to be SpaceX for fusion: take proven government-funded science, apply private-sector execution, and compress timelines by a decade.
This is a Series A. The company was founded in 2024 and closed $450 million before most startups have figured out their second hire. Bessemer – a firm that backed LinkedIn, Shopify, and Twilio itself – doesn’t move at that scale without a founder track record and scientific results that hold up under scrutiny. Want to understand how companies get to rounds like this? This breakdown of how one startup raised three rounds in 8 weeks lays out the mechanics.
The Hustler’s Library Take
Lawson’s ability to raise $450M for a two-year-old energy company wasn’t luck. It was a credibility compound built over two decades. His job at Inertia isn’t to understand laser physics – it’s to be the credibility bridge that convinces world-class scientists and tier-one investors that this time, someone with the right resources will actually do it. Dr. Kritcher spent 20+ years at LLNL. She didn’t leave on a prayer. She left because the team and the capital were serious.
That’s the transferable lesson: serious talent joins when they believe the company can actually win, not just that the vision is compelling. Building a pitch for investors? Start with how to find angel investors who will actually take your call. Trying to understand what makes operators bet on early-stage founders? This breakdown of why serious operators back specific founders is the place to start.
What You Should Do
Lead with proven validation, not vision alone. Bessemer invested because the NIF had already proven the physics. What have you already demonstrated that removes a major question mark for an investor or key hire?
Frame your raise around risk reduction. The $450M pitch wasn’t “fusion is a big market.” It was “the science is proven, the bottleneck is engineering and capital, here’s the roadmap.” Be specific about what risk your raise is designed to retire.
Build the credibility today that funds the big swings tomorrow. Every customer you retain, every team member who grows, every promise you keep is equity in your eventual ability to attract the next serious bet. Lawson’s Inertia round was 20 years in the making.
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