Investment
Capital in this sector is not mostly venture equity. Government milestone awards, grants and offtake agreements move comparable sums and mean entirely different things.
So there is no single “total raised” figure here. Equity is summed separately from awards, and a commitment paid against milestones is not counted as cash received. Merging them would produce a number that looks authoritative and means nothing.
Equity raised
| Company | Equity | Rounds | Non-equity | Unpriced |
|---|---|---|---|---|
| Commonwealth Fusion Systems | $1.80B | 1 | — | 1 |
| Pacific Fusion | $900M | 1 | — | — |
| TerraPower | $830M | 1 | — | — |
| X-energy | $700M | 1 | — | — |
| Helion Energy | $500M | 1 | — | 1 |
| TAE Technologies | $250M | 1 | — | — |
| Zap Energy | $160M | 1 | — | 1 |
| Proxima Fusion | $140M | 1 | — | — |
| Tokamak Energy | $125M | 1 | — | — |
| Xcimer Energy | $100M | 1 | — | 1 |
| Type One Energy | $82M | 1 | — | 1 |
| Marvel Fusion | $68M | 1 | — | — |
| Acceleron Fusion | $24M | 1 | — | — |
| Maritime Fusion | $5M | 1 | — | — |
Non-USD rounds are converted at the rate for the round's own date, never today's. “Unpriced” counts commitments and listings recorded without an amount.
All deals (22)
| Date | Company | Instrument | Amount | Detail |
|---|---|---|---|---|
| 2025-11 | Maritime Fusion | Equity round Seed | $5M | Seed round led by Trucks VC, with Aera VC, Alumni Ventures, Y Combinator and angel investors. |
| 2025-06 | Proxima Fusion | Equity round Series A | $140M EUR 130M | |
| 2025-02 | X-energy | Equity round Series C | $700M | |
| 2024-12 | Acceleron Fusion | Equity round Series A | $24M | Series A led by Lowercarbon Capital and Collaborative Fund. |
| 2024-11 | Tokamak Energy | Equity round Growth | $125M | |
| 2024-10 | Pacific Fusion | Equity round Series A | $900M | Series A committed in tranches against technical milestones. |
| 2024-06 | Marvel Fusion | Equity round Series B | $68M EUR 63M | |
| 2024-05 | Oklo | SPAC merger | unpriced | Public listing via SPAC merger. |
| 2024-02 | Type One Energy | Equity round Seed | $82M | |
| 2024-02 | Xcimer Energy | Equity round Series A | $100M | |
| 2023-05 | Commonwealth Fusion Systems | Milestone-based award | unpriced | DOE Milestone-Based Fusion Development Program Selected for the DOE Milestone-Based Fusion Development Program. |
| 2023-05 | Type One Energy | Milestone-based award | unpriced | DOE Milestone-Based Fusion Development Program |
| 2023-05 | Xcimer Energy | Milestone-based award | unpriced | DOE Milestone-Based Fusion Development Program |
| 2023-05 | Zap Energy | Milestone-based award | unpriced | DOE Milestone-Based Fusion Development Program |
| 2023-05 | Realta Fusion | Milestone-based award | unpriced | DOE Milestone-Based Fusion Development Program |
| 2023-05 | Focused Energy | Milestone-based award | unpriced | DOE Milestone-Based Fusion Development Program |
| 2023-05 | Helion Energy | Offtake or power purchase agreement | unpriced | 50 MW to Microsoft from 2028 Power purchase agreement for fusion-generated electricity. |
| 2022-08 | TerraPower | Equity round Growth | $830M | |
| 2022-07 | TAE Technologies | Equity round Growth | $250M | |
| 2022-06 | Zap Energy | Equity round Series C | $160M | |
| 2021-12 | Commonwealth Fusion Systems | Equity round Series B | $1.80B | Eni, Breakthrough Energy Series B financing. |
| 2021-11 | Helion Energy | Equity round Series E | $500M+ | Series E, with a further commitment tied to performance milestones. |
8 of 22 deals carry no amount on purpose: an award ceiling is not cash received, a SPAC headline is not proceeds after redemptions, and an offtake commits capacity rather than capital.