In recent years, nuclear fusion energy has shed its long-standing reputation as a technology perpetually "ten years away from commercialization," transforming into an increasingly attainable and attractive field that has successfully drawn in a wave of previously hesitant investors.

Despite the current significant technical challenges and high construction costs, nuclear fusion holds the promise of replicating the sun's nuclear reaction process to provide Earth with a near-limitless source of clean energy. Should startups succeed in building commercially viable fusion power plants, they stand to disrupt the multi-trillion-dollar global energy market.

This bullish sentiment in the fusion industry is driven by three key technological breakthroughs: more powerful computer chips, advanced artificial intelligence, and high-performance high-temperature superconducting magnets. These technologies work in synergy, enabling more sophisticated reactor designs, more accurate simulations, and more complex control systems.

A significant catalyst for the industry occurred in late 2022, when a US Department of Energy laboratory announced the achievement of a net energy gain in a controlled fusion reaction—where the energy produced by fusion exceeded the energy delivered by the lasers to the fuel target. This experiment achieved the scientifically recognized milestone of 'scientific energy breakeven.' While the path to commercial energy breakeven—where fusion output surpasses the total energy consumption of the entire plant—remains long, this long-awaited breakthrough validated the fundamental scientific principles of fusion.

In the years following, company founders have capitalized on this momentum, propelling the private fusion industry into a period of rapid development.

Commonwealth Fusion Systems (CFS) This company's funding accounts for approximately one-third of all private investment raised by global fusion firms. It completed its latest funding round in August, raising $863 million, bringing its total funding close to $3 billion.

This Series B2 round came four years after its $1.8 billion Series B round, which had previously propelled the company to the top of the industry. Since then, the Massachusetts-based startup has focused on advancing the construction of its Sparc power plant—its first fusion facility, designed to achieve a commercially relevant scale of power generation.

The Sparc reactor employs a tokamak design (shaped like a doughnut), with a D-shaped cross-section wound with high-temperature superconducting tape. When electrified, this creates a powerful magnetic field that confines and compresses super-hot plasma; the heat from the fusion reaction is then converted to steam to drive turbines for electricity. CFS's magnet technology was co-developed with MIT, and its co-founder and CEO, Bob Mumgaard, previously conducted research on fusion reactor design and high-temperature superconductors at MIT.

CFS anticipates that the Sparc plant will become operational by late 2026 or early 2027; later this decade, the company plans to commence construction on its Arc commercial power plant, which will have a generating capacity of 400 megawatts. Located near Richmond, Virginia, Google has already signed a contract to purchase half of its power output.

Notable Investors: Breakthrough Energy Ventures, The Engine, Bill Gates.

TAE Technologies Formerly known as Tri Alpha Energy, the company was spun out of UC Irvine in 1998 by Norman Rostoker. Its core technology is based on field-reversed configuration fusion, with a key innovation: after two plasma beams collide in the reactor's center, the company uses particle beams to bombard the plasma, causing it to maintain a cigar-like rotation. This enhances plasma stability, prolongs the duration of the fusion reaction, and allows for more heat extraction to drive turbines.

In December 2025, TAE announced a merger with Trump Media & Technology Group, a social media company associated with Donald Trump. This all-stock transaction valued the combined entity at $6 billion. TAE is set to receive $200 million in funding, with an additional $100 million available after filing with the SEC; TAE CEO Michl Binderbauer will serve as co-CEO of the merged company alongside Devin Nunes, the former sole CEO of Trump Media.

In June of this year, TAE secured an additional $150 million from existing investors including Google, Chevron, and New Enterprise Associates. According to PitchBook data, TAE's total funding prior to the merger reached $1.79 billion.

Helion Energy Among all fusion startups, Helion has the most aggressive commercialization timeline: it plans to connect a reactor to the grid by 2028, with Microsoft signed as its first customer.

Based in Everett, Washington, Helion uses a field-reversed configuration reactor design: the reaction chamber is shaped like an hourglass, with bulges where the two ends meet, surrounded by magnets. Workers form plasma into doughnut-shaped rings at each end of the hourglass and fire them towards each other at speeds exceeding one million miles per hour. After the plasma rings collide in the center, auxiliary magnets induce fusion. The fusion reaction itself amplifies the plasma's own magnetic field, generating an electrical current in the reactor's magnetic coils, allowing power to be collected directly from the device.

In January 2025, Helion completed a $425 million funding round and simultaneously began operating its Polaris prototype reactor. According to PitchBook, the company's total funding has reached $1.03 billion, with investors including Sam Altman, Reid Hoffman, KKR, BlackRock, Mithril Capital (founded by Peter Thiel), and Capricorn Investment Group.

Pacific Fusion Pacific Fusion made a notable debut by securing a $900 million Series A round, a colossal amount even within the well-funded fusion sector. The company employs an inertial confinement fusion approach but, instead of using lasers to compress fuel, utilizes coordinated electromagnetic pulses to achieve fusion. The core challenge lies in pulse timing control: 156 impedance-matched Marx generators must synchronously produce 2 terawatts of power for 100 nanoseconds, with all pulses precisely converging on the fuel target.

The company boasts a high-profile management team: CEO Eric Lander was a lead scientist of the Human Genome Project, and the President is Will Reagan. Despite the large funding amount, the capital is not disbursed all at once; investors will provide funding in stages as the company achieves predefined technical milestones, a model common in the biotech industry.

Shine Technologies Shine Technologies is pursuing a cautious and pragmatic path to fusion power: recognizing that connecting a fusion plant to the grid for electricity sales is still years away, the company is first entering the market with neutron inspection services and sales of medical isotopes. It is also recently developing radioactive waste recycling technology. The company has not yet finalized the technical path for its future fusion reactor, stating only that it is building core capabilities in preparation for technological maturity.

According to PitchBook data, the company has raised a total of $778 million. Investors include Energy Ventures, Koch Disruptive Technologies, Nucleation Capital, and the Wisconsin Alumni Research Foundation.

General Fusion Having entered its third decade of operation, General Fusion has accumulated $462.53 million in funding according to PitchBook. Founded in 2002 by physicist Michel Laberge and based in Richmond, British Columbia, Canada, its core technology is Magnetized Target Fusion (MTF), aimed at proving the viability of this approach. Investors include Jeff Bezos, Temasek, BDC Capital, and Chrysalix Venture Capital.

General Fusion's reactor design features a reaction chamber surrounded by a wall of liquid metal, into which plasma is injected. Pistons located outside the liquid metal wall compress inward, squeezing the internal plasma and triggering fusion. The neutrons produced by the reaction heat the liquid metal, which then passes through a heat exchanger to produce steam for turbine generation.

In the spring of 2025, General Fusion encountered difficulties: while building its latest device, LM26 (planned to achieve energy breakeven by 2026), it faced a cash flow shortage. Just days after achieving a key technical milestone, the company announced a 25% workforce reduction; CEO Greg Twinney issued a public letter urgently requesting additional investment from its backers.

In August of this year, investors provided $22 million through a "participatory financing" round, with one investor describing it as the "minimum necessary funding to keep the company operating." According to The Globe and Mail, Canadian securities filings in November showed the company raised $51.1 million from nearly 70 investors using a Simple Agreement for Future Equity (SAFE). PitchBook data now shows General Fusion's total funding has reached $492 million.

Tokamak Energy This company has optimized the traditional tokamak (doughnut-shaped) design by reducing the aspect ratio, giving its reactors a more spherical external profile. Like other tokamak-focused startups, it uses high-temperature superconducting magnets made from Rare Earth Barium Copper Oxide (REBCO). The more compact design compared to conventional tokamaks requires fewer magnets, potentially lowering construction costs.

Based in Oxfordshire, UK, the company's ST40 prototype reactor, built in 2022 (resembling a steampunk Fabergé egg), successfully generated plasma at an extreme temperature of 100 million degrees Celsius. It is currently building its next-generation device, Demo 4, aimed at validating magnet performance under "realistic power plant conditions." In November 2024, Tokamak Energy secured $125 million in funding to advance reactor design and expand its magnet business.

According to PitchBook, the company's total funding is $336 million. Investors include Future Planet Capital, the CIA's venture arm In-Q-Tel, Midven, and Hans-Peter Wild, founder of Capri-Sun.

Zap Energy Zap Energy does not use high-temperature superconducting magnets or powerful lasers to confine plasma. Instead, it zaps the plasma with an electrical current (the name "Zap" signifies this "electrical jolt"), causing the plasma itself to generate a magnetic field. This field compresses the plasma to about 1 millimeter, triggering fusion ignition. Neutrons released by the fusion reaction strike a liquid metal blanket surrounding the reactor, heating the metal, which then passes through a heat exchanger to produce steam for power generation.

Also based in Everett, Washington, Zap Energy has raised a total of $327 million according to PitchBook. Investors include Breakthrough Energy Ventures (founded by Bill Gates), DCVC, Lowercarbon Capital, Energy Impact Partners, and Chevron Technology Ventures. Bill Gates also participated as an angel investor.

Proxima Fusion While most investors favor leading startups pursuing tokamak or various inertial confinement approaches, stellarators have demonstrated significant potential in scientific experiments, such as Germany's Wendelstein 7-X.

Proxima Fusion is bucking the trend, having completed a €130 million Series A round, bringing its total funding to over €185 million. Investors include Balderton Capital and Cherry Ventures.

Stellarators are similar in principle to tokamaks, as both use powerful magnets to confine plasma in a toroidal (ring) shape. However, a key difference exists: instead of forcing plasma into an artificially designed ring, stellarators use twisted magnets and bulges in the chamber to adapt to the natural movement of the plasma. This allows the plasma to remain stable for longer periods, increasing the probability of fusion reactions.

Kyoto Fusioneering Amidst the focus on fusion power generation, it is inevitable that some companies would concentrate on developing supporting equipment to strengthen the supply chain. The "Balance of Plant" for a fusion power station refers to all supporting equipment outside the reactor itself, including gyrotrons for plasma heating, heat exchangers for recovering fusion energy, and power conversion systems.

Kyoto Fusioneering anticipated early on that as soon as any fusion company succeeds in selling grid-connected power, the industry will urgently need suppliers for Balance of Plant systems and the specialized expertise to integrate these systems with various fusion technologies.

This assessment has gained traction with venture capital firms. The company has raised a cumulative $191 million. Investors include 31Ventures, In-Q-Tel, Japan Industrial Partners, Mitsubishi, and Sumitomo Mitsui Trust Investment.

Marvel Fusion Marvel Fusion employs an inertial confinement fusion approach, sharing the core scientific principle behind the net energy gain achieved by the US National Ignition Facility: firing powerful lasers at a fuel target embedded with silicon nanostructures. When hit by the lasers, these nanostructures initiate a cascading reaction that compresses the fuel to ignition conditions. Because the fuel targets use silicon as a base material, they can leverage decades of semiconductor manufacturing expertise for mass production, making them relatively easier to produce.

Headquartered in Munich, Germany, the company is collaborating with Colorado State University to build a demonstration device scheduled for operation in 2027. According to PitchBook, Marvel Fusion has raised a total of $162 million. Investors include b2venture, Deutsche Telekom, Earlybird Venture Capital, and HV Capital, with Taavet Hinrikus and Albert Wenger participating as angel investors.

First Light Fusion Unlike most fusion startups, First Light Fusion does not rely on magnets to create fusion conditions. Its core technology is inertial confinement fusion—achieving ignition by compressing a fusion fuel target.

Even within the inertial confinement approach, the company diverges from mainstream methods. While leading projects like the National Ignition Facility use lasers for compression, First Light Fusion uses a two-stage gas gun to fire a projectile at the target. The first stage uses gas pressure to launch a plastic piston, compressing hydrogen to 145,000 pounds per square inch, which then launches the projectile. The target is specially designed to amplify the impact force, compressing the fuel to the ignition threshold.

In March 2025, First Light Fusion announced it was abandoning its own plans to build a power plant, opting instead to license its core technology to other companies who would construct the plants. A company spokesperson stated the plan is to build a "pulsed power device as a demonstration project while expanding applications in scientific research and defense," indicating that revenue generation has taken precedence over direct power plant development for now.

Based in Oxfordshire, UK, First Light Fusion has raised a total of $108 million according to PitchBook. Investors include Invesco, IP Group, and Tencent.

Xcimer Energy Nothing in fusion is simple, but Xcimer's technical approach is relatively straightforward: it is rebuilding the underlying technology from the ground up, based on the core scientific principles behind the net energy gain achieved by the US National Ignition Facility. The Colorado-based company aims to build a 10-megajoule laser system, five times more powerful than the NIF's record-setting device. The reactor chamber will be lined with a molten salt wall, which absorbs heat while protecting the first solid wall from damage.

Founded in January 2022, Xcimer has completed $100 million in funding according to PitchBook. Investors include Hedosophia, Breakthrough Energy Ventures, Emerson Collective, Gigascale Capital, and Lowercarbon Capital.