Mainspring is developing a new approach to generating clean, resilient, affordable electricity. Their research into high-efficiency methods of converting fuel to electricity led to the development and prototype of their first linear generator. This company was founded by John Connolly and Marshall Micheals in 1996 and is headquartered in Cambridge, MA.

Register for Details

For more details on financing and valuation for Mainspring, register or login.

Please provide a valid email address.

By registering, you agree to Forge’s Terms of Use. Already registered? Log in

Learn More About Mainspring

To invest in Mainspring pre-IPO

Can you invest in Mainspring pre-IPO?

Mainspring is a privately held company and is not publicly traded, therefore investing in Mainspring pre-IPO is only available to accredited investors. If you meet the accreditation criteria, you can learn more about Forge’s Secondary Marketplace and how to invest in private companies before their potential IPO. If you are not accredited, find out how to begin the process and qualify for new investment opportunities.

Can you sell shares of Mainspring before it goes public?

You can seek to sell your shares in Mainspring while it remains private. If you are considering selling, you can register today for free to get started. Once registered, a Private Market Specialist will guide you through any questions you might have. You may also continue to browse through our resources to help you understand the implications and procedures involved in selling your private market shares.

What is the pre-IPO value of my Mainspring shares?

To determine the value of your Mainspring shares, create a free account to gain access to Forge’s platform. In addition to the Forge Price, Forge Markets contains pricing information for hundreds of pre-IPO companies such as Last Closed Trade Price. A Private Market Specialist will also be available to assist you with any inquiries related to your Mainspring shares. You can also learn more about how to sell your private shares before getting started.

Is Mainspring a publicly traded company?

If you are interested in buying or selling private company shares, you can register with Forge today for free to explore your options. Registering gives you access to one of our Private Market Specialists who can guide you through the process of buying or selling. Learn more about how Forge might help you buy pre-IPO shares or sell pre-IPO shares.

To learn more about Mainspring potential IPO

Will Mainspring go IPO?

Mainspring has not yet filed for an IPO. However, it’s important to note that IPOs are not the sole avenue for a private company to transition to public trading. Private companies can also go public through alternative methods such as but limited to Special Purpose Acquisition Companies (SPACs), direct listings, or mergers and acquisitions. Find out which companies are eyeing an IPO on our Tech IPO Calendar 2024.

What is Mainspring’s IPO price?

The Mainspring IPO price does not exist at this time, as Mainspring is still a private company and has not yet conducted an IPO. To explore secondary market data and access private market pricing details and data that may be related to Mainspring register for Forge Markets, today.

When was Mainspring founded?

Mainspring was founded in 2010.

What is Mainspring funding to date?

Mainspring has raised $746.62MM to date.

Who are Mainspring’s major investors?

Aep
Kck
Chevron Technology Ventures
Princeville Capital
Clearsky
Louis M. Bacon
Kck Group
Equinor
Devonshire Investors
Lineage Ventures
Khosla Ventures
Centrica Innovations
Cpp Investments
Undisclosed Investors
Hanwha Power Systems
Shell Ventures
Fidelity
American Electric Power
Lightrock
40 North Ventures
Statoil Energy Ventures
Fine Structure Ventures
Bill Gates

Mainspring Funding Rounds and Valuation

Funding History Chart
Funding Round Details
Funding Date Share Class Amount Raised Price per Share Post-Money Valuation Key Investors
11/26/2024 Series F-1 $41.14MM $xx.xx $1.51B Undisclosed Investors
Price per Share
$xx.xx
Shares Outstanding
13,821,080
Liquidation Pref Order
1
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
Undisclosed Investors
11/26/2024 Series F $159.55MM $xx.xx $1.51B Undisclosed Investors
Price per Share
$xx.xx
Shares Outstanding
42,882,709
Liquidation Pref Order
1
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
Undisclosed Investors
09/21/2022 Series E-1 $18.91MM $xx.xx $1.04B Bill Gates, Cpp Investments, Fidelity, Fine Structure Ventures, Hanwha Power Systems, Khosla Ventures, Lightrock, Lineage Ventures, Princeville Capital, Shell Ventures
Price per Share
$xx.xx
Shares Outstanding
2,467,100
Liquidation Pref Order
2
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
Bill Gates, Cpp Investments, Fidelity, Fine Structure Ventures, Hanwha Power Systems, Khosla Ventures, Lightrock, Lineage Ventures, Princeville Capital, Shell Ventures
09/21/2022 Series E $284.47MM $xx.xx $1.04B Bill Gates, Cpp Investments, Fidelity, Fine Structure Ventures, Hanwha Power Systems, Khosla Ventures, Lightrock, Lineage Ventures, Princeville Capital, Shell Ventures
Price per Share
$xx.xx
Shares Outstanding
35,251,855
Liquidation Pref Order
2
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
Bill Gates, Cpp Investments, Fidelity, Fine Structure Ventures, Hanwha Power Systems, Khosla Ventures, Lightrock, Lineage Ventures, Princeville Capital, Shell Ventures
05/04/2021 Series D $108.35MM $xx.xx $440.31MM 40 North Ventures, Aep, Bill Gates, Chevron Technology Ventures, Clearsky, Devonshire Investors, Equinor, Kck, Khosla Ventures, Princeville Capital
Price per Share
$xx.xx
Shares Outstanding
20,055,578
Liquidation Pref Order
3
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
40 North Ventures, Aep, Bill Gates, Chevron Technology Ventures, Clearsky, Devonshire Investors, Equinor, Kck, Khosla Ventures, Princeville Capital
01/24/2018 Series C $84.3MM $xx.xx $245.46MM American Electric Power, Bill Gates, Centrica Innovations, Kck Group, Khosla Ventures, Louis M. Bacon, Statoil Energy Ventures
Price per Share
$xx.xx
Shares Outstanding
19,546,914
Liquidation Pref Order
4
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
American Electric Power, Bill Gates, Centrica Innovations, Kck Group, Khosla Ventures, Louis M. Bacon, Statoil Energy Ventures
08/29/2017 Series B $40.04MM $xx.xx $110.16MM Undisclosed Investors
Price per Share
$xx.xx
Shares Outstanding
10,569,940
Liquidation Pref Order
5
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
Undisclosed Investors
07/01/2011 Series A $2.86MM $xx.xx $25.97MM Undisclosed Investors
Price per Share
$xx.xx
Shares Outstanding
3,169,952
Liquidation Pref Order
5
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
Undisclosed Investors
07/01/2011 Series A-1 $7MM $xx.xx $25.97MM Undisclosed Investors
Price per Share
$xx.xx
Shares Outstanding
3,708,413
Liquidation Pref Order
5
Liquidation Pref As Multiplier
1.0x
Conversion Ratio
1.0x
Dividend Rate
8.0%
Cumulative
Non-cumulative
Participating
Non-participating
Participation Cap
--
Key Investors
Undisclosed Investors
Updated on: Dec 23, 2024

PLEASE READ THESE IMPORTANT LEGAL NOTICES & DISCLOSURES

‘Stock Price’ or other private company metrics (‘PC Data’) may rely on a very limited number of trade and/or IOI inputs in their calculation. PC Data is prepared and disseminated solely for informational purposes. While Forge has obtained information from sources it believes to be reliable, Forge does not perform an audit or undertake any duty of due diligence or independent verification of any information it receives. Forge does not guarantee the accuracy, completeness, timeliness, or availability of PC Data, and are not responsible for any errors or omissions, regardless of the cause, or any results obtained from the use of PC Data. PC Data is derived from the performance and pricing of secondary activity on the Forge platform and other private market trading platforms. PC Data is not intended to, and does not necessarily, represent the market price of any securities (I.e., the price at which you could buy or sell such securities). Reference to company names does not imply any affiliation between Forge and that company, any endorsement or sponsorship by Forge of any company or vice versa, or any partnership, joint venture or other commercial relationship between Forge and any company. Rights with respect to any company marks referred to herein are owned by the company.

Public news articles listed on this page have been curated by Forge based on several factors including, but not limited to, product updates, changes in organization structure, funding rounds, third-party valuations, and key personnel changes. Changes to this list of articles can be made at any time without notice and should not be relied upon for investment purposes. Forge does not verify the accuracy of the information contained in public news articles.

Investing in private company securities is not suitable for all investors, is highly speculative, is high risk, and investors should be prepared to withstand a total loss of their investment. Private company securities are highly illiquid and there is no guarantee that a market will develop for such securities. Each investment carries its own risks, and investors should conduct their own due diligence regarding the investment, including obtaining independent professional advice. Past performance is not indicative of future results. This is not a recommendation, offer, solicitation of an offer, or advice to buy or sell securities by Forge, nor an offer of brokerage services in any jurisdiction where Forge is not permitted to offer brokerage services. Brokerage products and services are offered by Forge Securities LLC, a registered broker-dealer and member FINRA/SIPC. Please see other important disclaimers, disclosures and restrictions you acknowledge by using this website and to which you are subject.