Inertia Enterprises, a fusion energy company based in Livermore, California, raised $450m in a Series A round, it announced on 11 February 2026.
Bessemer Venture Partners led the round. GV (Google Ventures), Modern Capital and Threshold Ventures also invested, along with other firms the company did not name. Inertia did not disclose a valuation.
The company said the funding is milestone-based. It will pay for work on Thunderwall, a high-power laser, and on a production line to mass-manufacture fusion fuel targets, the two technical tracks Inertia says underpin its plan for a pilot plant.
“Our plan is clear: build on proven science to develop the technology and supply chain required to deliver the world's highest average power laser, the first fusion target assembly plant, and the first gigawatt, utility-scale fusion power plant to the grid.”Jeff Lawson, Co-founder and CEO, Inertia
What Inertia does
Founded in 2024, Inertia is pursuing laser-driven inertial fusion, in which powerful lasers compress small fuel targets until they fuse. Its plans build on research at the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. In December 2022 an experiment there became the first controlled fusion experiment to produce more energy from fusion than was delivered to the target.
The centrepiece of Inertia's design is Thunderwall, which the company describes as the first grid-scale fusion laser beamline. It is designed to deliver a 10 kJ beam ten times a second at 10% wall-plug efficiency, using semiconductor diode technology. Inertia says that would give it 50 times the average power of any previous laser of its type. The plant would also need mass-produced targets and a system that feeds them into the laser chambers in fractions of a second.
The company says it aims to deliver a gigawatt-scale, utility fusion power plant to the grid within the next decade.
The founders
Inertia has three co-founders. Chief executive Jeff Lawson founded the communications software company Twilio and ran it for many years. Chief scientist Annie Kritcher has been lead designer of fusion experiments at NIF since 2017 and has spent more than 20 years at the laboratory. She led the "Hybrid-E" design behind the December 2022 result and, under what the company calls a first-of-its-kind agreement, keeps her role at the laboratory while working for Inertia.
Chief technology officer Mike Dunne joined from Stanford University and SLAC National Accelerator Laboratory, where he directed the Linac Coherent Light Source. He previously led a five-year programme at Lawrence Livermore to create a power plant design based on the laboratory's ignition approach, and before that directed the UK's Central Laser Facility.
"In just three years, we've gone from the first experiment to ever produce more fusion energy than was delivered to the target, to repeating that result many times and pushing the target gain higher," Kritcher said in the announcement.
Who invested
Byron Deeter, a partner at Bessemer, said the deal was the firm's first investment in the direct fusion market. He said Inertia was the first company Bessemer had seen with a clear roadmap to commercial energy.
Besides the investors in the round, Inertia's company description lists Neo, Uncork Capital, Long Journey Ventures, WndrCo and IQT among its backers. The company did not say how much each investor contributed or whether it had raised money before the Series A.
Inertia is not the only company working on laser-driven fusion. Heatmap noted that Xcimer Energy, another start-up in the field, raised a $100m Series A in 2024, and wrote that the new round leaves Inertia by far the best capitalised of the group.
Company website: inertia.com