Mainspring Energy
PrivateLast Round
Series F
Apr 14, 2025
Total Funding Raised
$820M
Momentum
Top 10%
of companies Caplight tracks
Company Overview
Mainspring Energy is a clean energy company that manufactures and delivers fuel-flexible linear generators designed to provide affordable, reliable, and net-zero carbon electricity.
Sector
Energy & Sustainability
Verticals
Renewable Energy, Energy Storage
Business Model
B2B
Customer Profile
Hardware Sales, Services & Consulting, Hardware + Subscription
AI Layer
Non-AI
Keywords
Historical Pricing
Historical view of private secondary pricing and transaction trends.
Mainspring Energy Comparables
Compare Mainspring Energy with similar companies based on industry and business-model similarity.
| Company | Similarity | Market Cap |
|---|---|---|
| Hyliion | 82% | |
| Bloom Energy | 80% | |
| Capstone Green Energy Holdings | 79% |
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Mainspring Energy Funding Rounds
Historical fundraising activity
| Round | Date | Amount Raised | Valuation | Investors | Sources |
|---|---|---|---|---|---|
| Series F | Apr 14, 2025 | ||||
| Grant | Oct 22, 2024 | ||||
| Series E | Sep 21, 2022 | ||||
| Series D | May 4, 2021 | ||||
| Series C | Jan 24, 2018 |
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Key People
Founding team and executive leadership
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Mainspring Energy Investors
Notable investors and investment history
| Investor | Rounds |
|---|---|
| CPP Investments | Series E |
| Pictet Group | Series F |
| 40 North Ventures | Series D |
| ClearSky | Series D |
| Fine Structure Ventures | Series E |
| Temasek | Series F |
| Khosla Ventures | Series F, Series D, Series E, Series C, Series A |
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Market signals
Structured signals derived from secondary market and firmographic data.
- Oct 15, 2026
Partnerships announced with AEP, NextEra Energy Resources, and Schneider Electric.
- Oct 15, 2026
Mainspring Linear Generators began commercial shipments in 2020.
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Recent news
Latest coverage and updates
- receives_financingOct 15, 2026
Mainspring Energy, Inc. recently receives $242M in Series G financing led by Valiant Peregrine, with participation from all existing investors and a new strategic backer.
- signs_new_clientOct 13, 2026
On Oct 13th '26, Mainspring Energy, Inc. strikes a deal to supply AEP with up to 1.6 gigawatts of generation capacity, and the agreement could be worth as much as $4 billion over eight years.
- expands_facilitiesAug 31, 2026
Mainspring Energy, Inc. plans to establish a manufacturing center in Pennsylvania, which is expected to employ about 120 workers during its initial phase, as discussed in Sep '26.
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Mainspring Energy Filings
Explore SEC and related filing metadata, where available.
| Type | Date | Amount Offered | Amount Sold | Filing | Pages | Download |
|---|
Filing documents are not displayed on this public page. Request access to learn about available coverage.
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Frequently Asked Questions
Common questions about Mainspring Energy's valuation, stock price, and market status.
Is Mainspring Energy a public or private company?
Mainspring Energy is a private company.
What is the current stock price of Mainspring Energy?
Mainspring Energy is a private company, so its shares have no public market price. Caplight tracks Mainspring Energy's secondary market activity and provides MarketPrice™ estimates of its share price to Caplight users.
How much is Mainspring Energy worth (valuation)?
Valuation information for Mainspring Energy is not publicly available.
Can I buy Mainspring Energy stock?
Mainspring Energy shares may be available on secondary markets subject to transfer restrictions. Caplight facilitates secondary market transactions for accredited investors.
When was Mainspring Energy's last funding round?
Mainspring Energy's most recent funding round was Series F on April 14, 2025.
Who are the main investors in Mainspring Energy?
Key investors in Mainspring Energy include Khosla Ventures, General Catalyst, Lightrock.
Will Mainspring Energy IPO soon?
No public IPO plans have been announced for Mainspring Energy.
How can I track Mainspring Energy secondary market activity?
Caplight tracks bids, offers, and trades in Mainspring Energy's shares on secondary markets.