Fine Structure Ventures is a venture capital fund affiliated with FMR LLC, the parent company of Fidelity Investments, focused on early-stage investments in disruptive scientific and technological innovation. As of July 1, 2024, F-Prime Capital advises Fine Structure Ventures. The firm is headquartered in Cambridge, Massachusetts.
32% of their portfolio is in Climate & Energy. Deal activity decreased year-over-year (4 deals in the last 12 months vs 7 prior). Average disclosed round size is $45.6M (across 35 rounds with reported amounts).
Portfolio
28
Fund Size
—
Top Stage
Series A
Last 12 Mo
4
Team
Portfolio Breakdown
Stage Distribution
Sector Distribution
Investment Activity
DealsAvg Round Size
Portfolio
38 investments
| Company | Round | Amount | Date |
|---|---|---|---|
 iPronics | Series B | $125M | Sep 2026 |
 Dg Matrix | Series A | $60M | Feb 2026 |
 Sepion Technologies | Series B | $10M | Jan 2026 |
 Ph7 | Series B | $25.6M | Dec 2025 |
 PH7 Technologies | Series B | $25.6M | Dec 2025 |
 Debut Biotechnology | Unknown | $20M | Aug 2025 |
 Aalo Atomics | Series B | $100M | Aug 2025 |
 Aalo | Series B | $100M | Aug 2025 |
 Finwave | Bridge | $8.2M | May 2025 |
 Mainspring Energy, Inc. | Series F | $258M | Apr 2025 |
 Nitricity | Seed | $10M | Mar 2025 |
| iPronics | Series A | — | Jan 2025 |
| FFinwave Semiconductor | Bridge | $8.2M | Jan 2025 |
 Constructive Bio | Series A | $58M | Sep 2024 |
 Feon Energy | Seed | $6.1M | Jun 2024 |
 Mantle | Series C | $20M | Jan 2024 |
 Osmoses | Seed | $11M | Oct 2023 |
 Caelux | Series A | $12M | Aug 2023 |
| Aalo Atomics | Seed | — | Jan 2023 |
 Hoxton Farms | Series A | — | Oct 2022 |
| Nitricity | Series A | $20M | Oct 2022 |
 Femtosense | Seed | $8M | Sep 2022 |
| Mainspring Energy, Inc. | Series E | $150M | Sep 2022 |
| Finwave | Series A | $12.2M | Jul 2022 |
| FFinwave Semiconductor | Series A | $4.3M | Jul 2022 |
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Top Co-Investors
Gaingels12 shared
Alumni Ventures8 shared
MCJ7 shared
Engine Ventures7 shared
Khosla Ventures5 shared
Safar Partners4 shared
Crosscut Ventures4 shared
Hitachi Ventures4 shared
Valor Equity Partners4 shared
Build Collective4 shared
SiteGround Capital4 shared
SpaceFund3 shared
Exor Ventures3 shared
The Private Shares Fund3 shared
The Venture Collective3 shared
Type One Ventures3 shared
GlobalFoundries3 shared
Fifty Years3 shared
Harpoon Ventures3 shared
Last updated: 20 October 2026