In recent years, fusion energy has transitioned from a source of amusement — perpetually a decade away! — to a concrete and alluring technology that has begun attracting investors.

While the technology remains difficult to perfect and costly to construct at present, fusion holds the promise of tapping into the nuclear processes that fuel the sun, creating an almost infinite source of energy on Earth. If startups succeed in creating commercially viable fusion power facilities, they could potentially disrupt trillion-dollar industries.

The optimistic surge uplifting the fusion sector has been propelled by three significant advancements: enhanced computer chips, advanced artificial intelligence, and robust high-temperature superconducting magnets. These innovations have facilitated the development of more advanced reactor designs, improved simulations, and intricate control systems.

Furthermore, in late 2022, a U.S. Department of Energy laboratory announced it had achieved a controlled fusion reaction that yielded more energy than the lasers delivered to the fuel pellet. This experiment reached what is referred to as scientific breakeven, and although commercial breakeven — where the reaction generates more energy than the entire facility consumes — is still far off, it was a long-awaited milestone confirming the validity of the underlying science.

In the past few years, founders have capitalized on this momentum, propelling the private fusion industry forward swiftly.

Commonwealth Fusion Systems

Commonwealth Fusion Systems (CFS) has secured roughly one-third of the private investment in fusion firms to date. Its most recent funding round, which concluded in August, added $863 million to its funding, bringing its total raised to almost $3 billion.

CFS’s Series B2 came four years after its $1.8 billion Series B, which propelled the company into the lead position. Since then, the startup has been diligently constructing Sparc in Massachusetts, a pioneering power plant designed to produce energy at what it terms “commercially relevant” levels. 

Sparc’s reactor adopts a tokamak design, resembling a doughnut. Its D-shaped cross-section is wrapped with high-temperature superconducting tape that, when energized, creates a powerful magnetic field to contain and compress the superheated plasma. The heat generated from the reaction is converted into steam to drive a turbine. CFS collaborated with MIT in the design of its magnets, where co-founder and CEO Bob Mumgaard previously researched fusion reactor designs and high-temperature superconductors.

Based in Massachusetts, CFS anticipates that Sparc will be operational by late 2026 or early 2027. The company also plans to commence construction on Arc, its commercial power facility aimed at generating 400 megawatts of electricity, later this decade. This facility will be located near Richmond, Virginia, and Google has agreed to purchase half of its output.

CFS enjoys backing from a diverse array of investors, including Breakthrough Energy Ventures, The Engine, Bill Gates, and many others.

TAE Technologies

Established in 1998, TAE Technologies (formerly Tri Alpha Energy) was developed at the University of California, Irvine by Norman Rostoker. It employs a field-reversed configuration, albeit with a unique approach: after two plasma shots collide at the reactor’s center, the company bombards the plasma with particle beams to maintain its cigar shape. This enhances plasma stability, allowing for longer fusion durations and greater heat extraction for turbine operation. 

In December 2025, TAE announced plans to merge with President Donald Trump’s social media firm, Trump Media & Technology Group. The all-stock deal would value the combination at $6 billion. TAE will receive $200 million plus an additional $100 million upon submitting documentation to the Securities and Exchange Commission. TAE CEO Michl Binderbauer will become co-CEO of the new entity alongside Devin Nunes, the former sole CEO of Trump Media.

Previously, the fusion startup raised $150 million in June from existing backers, including Google, Chevron, and New Enterprise. Prior to the merger, TAE had accumulated $1.79 billion, according to PitchBook.

Helion

Among fusion startups, Helion boasts the most ambitious timeline, aiming to generate electricity from its reactor by 2028. Its initial customer? Microsoft.

Helion, located in Everett, Washington, utilizes a field-reversed configuration reactor, wherein magnets encircle a reaction chamber resembling an hourglass with a bulge at the junction of the two sides. At each end of the hourglass, the plasma is spun into doughnut shapes that are propelled toward each other at over 1 million mph. Upon collision, additional magnets facilitate fusion. The occurrence of fusion amplifies the plasma’s magnetic field, inducing an electric current within the reactor’s magnetic coils, which is then harnessed directly.

The company secured $425 million in January 2025, around the same timeframe it activated Polaris, a prototype reactor. Helion has raised a total of $1.03 billion, according to PitchBook. Investors include Sam Altman, Reid Hoffman, KKR, BlackRock, Peter Thiel’s Mithril Capital Management, and Capricorn Investment Group.

Pacific Fusion

Pacific Fusion launched with an impressive $900 million Series A, a considerable amount even among well-financed fusion startups. The company intends to pursue inertial confinement for fusion, but instead of using lasers to compress the fuel, it will utilize synchronized electromagnetic pulses. Success hinges on timing: All 156 impedance-matched Marx generators must deliver 2 terawatts for 100 nanoseconds, with those pulses converging on the target simultaneously.

The organization is overseen by CEO Eric Lander, the scientist who led the Human Genome Project, and president Will Regan. Despite its massive funding, the startup hasn’t received it all in a single sweep. Instead, investors will release funds in stages as the company meets particular milestones, a strategy common in biotechnology.

Shine Technologies

Shine Technologies is adopting a measured — and possibly practical — path toward creating fusion power. Since selling electrons from a fusion power plant is years away, it is initially focusing on selling neutron testing and medical isotopes. Recently, it has also been working on a method to recycle radioactive waste. Shine has not settled on a specific design for a future fusion reactor, instead stating that it is acquiring essential skills for when that moment arrives.

The firm has raised a cumulative total of $778 million, as per PitchBook. Investors include Energy Ventures Group, Koch Disruptive Technologies, Nucleation Capital, and the Wisconsin Alumni Research Foundation.

General Fusion

Now entering its third decade, General Fusion has secured $462.53 million as reported by PitchBook. Founded in 2002 by physicist Michel Laberge in Richmond, British Columbia, the company aims to demonstrate an alternative fusion method known as magnetized target fusion (MTF). Investors involved include Jeff Bezos, Temasek, BDC Capital, and Chrysalix Venture Capital.

In General Fusion’s reactor, a chamber surrounded by a liquid metal wall receives injected plasma. Surrounding pistons compress the wall, pushing it inward, and leading to a fusion reaction. The resulting neutrons heat the liquid metal, which can then be cycled through a heat exchanger to create steam for turbine operation.

The company faced financial hurdles in spring 2025 as it was constructing LM26, its latest device, expected to reach breakeven in 2026. Shortly after achieving a key milestone, the company laid off 25% of its workforce. CEO Greg Twinney issued an open letter appealing for funding from investors. 

In August, they provided some assistance, injecting $22 million in a pay-to-play round, described by one investor as “the minimal capital needed” to keep General Fusion operational. Subsequently, in November, securities filings in Canada revealed the company had raised $51.1 million in SAFE notes from nearly 70 investors, reported the Globe and Mail. Overall, General Fusion has amassed $492 million as per PitchBook.

Tokamak Energy

Tokamak Energy transforms the traditional tokamak design — the doughnut shape — by compressing it, reducing its aspect ratio to the extent that the outer contours begin to resemble a sphere. Like many other tokamak-focused startups, the company utilizes high-temperature superconducting magnets (specifically of the rare earth barium copper oxide, or REBCO, type). Due to its compact design compared to standard tokamaks, it requires fewer magnets, potentially lowering costs. 

The Oxfordshire, U.K.-based startup’s ST40 prototype resembles a large, steampunk Fabergé egg and achieved ultra-hot plasma at 100 million degrees Celsius in 2022. Its next iteration, Demo 4, is presently under construction and aims to test the company’s magnets in scenarios relevant to a fusion power plant. Tokamak Energy raised $125 million in November 2024 to advance its reactor design and expand its magnet business.

In total, the firm has secured $336 million from investors including Future Planet Capital, In-Q-Tel, Midven, and Capri-Sun founder Hans-Peter Wild, according to PitchBook.

Zap Energy

Zap Energy does not rely on high-temperature superconducting magnets or powerful lasers to maintain plasma confinement. Instead, it energizes the plasma with an electric current, creating its own magnetic field. This magnetic field compresses the plasma by about 1 millimeter, initiating ignition. The neutrons generated by the fusion reaction hit a liquid metal blanket encasing the reactor, heating it up, which is then cycled through a heat exchanger to produce steam for turbine operation.

Like Helion, Zap Energy is also based in Everett, Washington, and has raised $327 million, according to PitchBook. Backers include Bill Gates’ Breakthrough Energy Ventures, DCVC, Lowercarbon, Energy Impact Partners, Chevron Technology Ventures, and Bill Gates in an angel capacity.

Proxima Fusion

While most investors have leaned towards large startups pursuing tokamak designs or variations of inertial confinement, stellarators have demonstrated significant potential in scientific trials, including Germany’s Wendelstein 7-X reactor.

Proxima Fusion is defying this trend, having secured a €130 million Series A, pushing its total funding above €185 million. Investors consist of Balderton Capital and Cherry Ventures.

Stellarators share similarities with tokamaks, confining plasma in a ring shape using powerful magnets. However, they twist and bulge innovatively to cater to plasma’s unique characteristics. This design is expected to allow for greater stability in the plasma, thus enhancing the probability of fusion events.

Kyoto Fusioneering

Amid numerous startups targeting fusion power, it was perhaps only a matter of time before one emerged to develop components that complete a power plant. The so-called balance of plant, or elements outside the reactor, includes gyrotrons for heating plasma and heat extraction systems to convert fusion energy into electricity. 

Kyoto Fusioneering has made an early investment, believing that if any fusion startup achieves sufficient power generation to sell to the grid, the industry will require a supplier for the balance of plant and the expertise to integrate it into whichever fusion methods prevail.

Venture capitalists seem to concur, having invested $191 million in Kyoto Fusioneering. Investors encompass 31Ventures, In-Q-Tel, JIC Venture Growth Investments, Mitsubishi, and Sumitomo Mitsui Trust Investment.

Marvel Fusion

Marvel Fusion adopts the inertial confinement methodology, the fundamental technique that the National Ignition Facility deployed to demonstrate that controlled nuclear fusion reactions could yield more energy than required to initiate them. Marvel directs powerful lasers at a target embedded with silicon nanostructures, which cascade under bombardment, compressing the fuel to ignition levels. Given that the target is constructed from silicon, it ought to be relatively simple to produce, drawing on the semiconductor manufacturing industry’s extensive experience.

The inertial confinement fusion startup is creating a demonstration facility in cooperation with Colorado State University, which aims to be operational by 2027. Based in Munich, Marvel has raised a total of $162 million from investors including b2venture, Deutsche Telekom, Earlybird, and HV Capital, with Taavet Hinrikus and Albert Wenger as angel investors.

First Light Fusion

In contrast to many other fusion startups, First Light Fusion does not employ magnets to create the conditions necessary for fusion. Instead, it follows a strategy referred to as inertial confinement, in which fusion fuel pellets are compressed until they ignite. 

Yet even here, First Light deviates from convention. The majority of inertial confinement efforts utilize lasers, inspired by the National Ignition Facility’s landmark experiment in 2022. Instead, First Light utilizes a two-stage gun to launch a projectile at a target; the first phase activates gunpowder to propel a plastic piston that compresses hydrogen to 145,000 psi, which subsequently fires the projectile. The target is specifically designed to amplify the impact force, ensuring the fuel is compressed sufficiently to ignite.

In March 2025, First Light declared it would abandon plans to construct its own power plant, opting instead to offer its core technologies to other companies for power plant construction. A spokesperson stated that the company intends to develop “pulsed power capability that would serve as our demonstrator plant but would have additional scientific and defense applications.” In essence, the company is pivoting away from its power plant aspirations to seek other revenue avenues.

Based in Oxfordshire, UK, First Light has raised $108 million from investors including Invesco, IP Group, and Tencent, according to PitchBook.

Xcimer

Although fusion remains a complex endeavor, Xcimer embraces a somewhat straightforward methodology: following the scientific principles behind the National Ignition Facility’s groundbreaking net-positive experiment and redesigning its foundational technology from scratch. The Colorado-based startup aims for a 10-megajoule laser system, five times more potent than the NIF design that made history. Molten salt walls encase the reaction chamber, absorbing heat and shielding the first solid wall from harm.

Founded in January 2022, Xcimer has already raised $100 million, according to PitchBook, from backers including Hedosophia, Breakthrough Energy Ventures, Emerson Collective, Gigascale Capital, and Lowercarbon Capital.

This article was initially published in September 2024 and will be regularly updated.