Every Fusion Startup That Has Raised Over $100M

Fusion power, once a joke, is now a tangible technology drawing investors. Startups aim to harness the nuclear reaction powering the sun for limitless energy. The fusion industry has gained momentum due to advances in computer chips, AI, and high-temperature superconducting magnets.

These developments have led to more sophisticated reactor designs, better simulations, and complex control schemes. In 2022, a US Department of Energy lab achieved a controlled fusion reaction producing more power than the lasers imparted to the fuel pellet. This experiment crossed scientific breakeven, proving the underlying science is sound.

Founders have built on this momentum, pushing the private fusion industry forward rapidly. Commonwealth Fusion Systems (CFS) has raised about a third of all private capital invested in fusion companies to date. Its latest round, which closed in August, added $863 million to its coffers, bringing its total raised near $3 billion.

CFS’s Series B2 came four years after its $1.8 billion Series B, which helped catapult the company into the pole position. Since then, the startup has been hard at work in Massachusetts building Sparc, its first-of-a-kind power plant intended to produce power at commercially relevant levels. Sparc’s reactor is a tokamak design, which resembles a doughnut.

The D-shaped cross section is wound with high-temperature superconducting tape, which, when energized, generates a powerful magnetic field that will contain and compress the superheated plasma. The Massachusetts-based CFS expects to have Sparc operational in late 2026 or early 2027. Later this decade, the company says it will begin construction on Arc, its commercial power plant that will produce 400 megawatts of electricity.

Commonwealth Fusion Systems is backed by a long list of investors, including Breakthrough Energy Ventures, The Engine, Bill Gates, and others. Founded in 1998, TAE Technologies (formerly known as Tri Alpha Energy) was spun out of the University of California, Irvine by Norman Rostoker. It uses a field-reversed configuration.

In December 2025, TAE announced that it would merge with President Donald Trump’s social media company, Trump Media & Technology Group. The all-stock transaction would value the combined company at $6 billion. TAE had previously raised $150 million in June from existing investors, including Google, Chevron, and New Enterprise.

Before the merger, TAE had raised a total of $1.79 billion. Helion has the most aggressive timeline, planning to produce electricity from its reactor in 2028. Its first customer is Microsoft.