As filed with the Securities and Exchange Commission on November 7, 2017March 12, 2021

Registration No. 333-

 

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington,WASHINGTON, D.C. 20549

 

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

 

Aspen Aerogels, Inc.

(Exact name of registrant as specified in its charter)

 

 

Delaware

Delaware04-3559972

(State or other

jurisdiction of

incorporation or organization)

(I.R.S. Employer

Identification Number)No.)

30 Forbes Road, Building B

Northborough, Massachusetts 01532

(508) 691-1111

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

 

Donald R. Young

President and Chief Executive Officer

Aspen Aerogels, Inc.

30 Forbes Road, Building B

Northborough, Massachusetts 01532

(508) 691-1111

(Name, address, including zip code, and telephone number, including area code, of agent for service)

 

Copies to:

Sahir Surmeli, Esq.

John T. Rudy, Esq.

Mintz, Levin, Cohn, Ferris, Glovsky and

Popeo, P.C.

One Financial Center

Boston, Massachusetts 02111

(617) 542-6000

 

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.registration statement becomes effective.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box:  

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box:  

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  


If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.  

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box.  

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company”company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

 

Large accelerated filer

Accelerated filer

Non-accelerated filer

(Do not check if a smaller reporting company)

Non-accelerated filerSmaller reporting company

Emerging growth company

Growth Company

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  

 


CALCULATION OF REGISTRATION FEE

 

Title of Each Class of

Securities to be Registered

Amount

to be

Registered(1)

Proposed

Maximum

Offering Price

Per Share(2)

Proposed

Maximum

Aggregate

Offering Price(2)

Amount of

Registration Fee

 

Amount
to be

Registered

 

Proposed
Maximum

Offering Price

per Unit

 

Proposed
Maximum

Aggregate

Offering Price

 

Amount of

Registration Fee(1)

Common Stock, par value $0.00001 per share

6,620,452 shares

$4.455

$29,494,114

$3,672.02

Common Stock, $0.00001 par value

 (2) (3) (3) —  

Preferred Stock, $0.00001 par value

 (2) (3) (3) —  

Debt Securities

 (2) (3) (3) —  

Warrants

 (2) (3) (3) —  

Rights

 (2) (3) (3) ��  

Units

 (2) (3) (3) —  

Total

 (2) (3) $250,000,000(3) $27,275

(1)

Calculated pursuant to Rule 457(o) under the Securities Act of 1933, as amended, based on the proposed maximum aggregate offering price.

(2)

There are being registered hereunder such indeterminate number of shares of common stock and preferred stock, such indeterminate principal amount of debt securities, such indeterminate number of warrants, rights to purchase common stock, preferred stock or debt securities, and such indeterminate number of units, as shall have an aggregate initial offering price not to exceed $250,000,000. If any debt securities are issued at an original issue discount, then the offering price of such debt securities shall be in such greater principal amount as shall result in an aggregate initial offering price not to exceed $250,000,000, less the aggregate dollar amount of all securities previously issued hereunder. Any securities registered hereunder may be sold separately or as units with other securities registered hereunder. The proposed maximum initial offering price per unit will be determined, from time to time, by the registrant in connection with the issuance by the registrant of the securities registered hereunder. The securities registered also include such indeterminate number of shares of common stock and preferred stock and amount of debt securities as may be issued upon conversion of or exchange for preferred stock or debt securities that provide for conversion or exchange, upon exercise of warrants or rights or pursuant to the anti-dilution provisions of any such securities. In addition, pursuant to Rule 416 under the Securities Act of 1933, as amended, the shares being registered hereunder include such indeterminate number of shares of common stock and preferred stock as may be issuable with respect to the shares being registered hereunder as a result of stock splits, stock dividends or similar transactions.

(3)

The proposed maximum aggregate offering price per class of security will be determined from time to time by the registrant in connection with the issuance by the registrant of the securities registered hereunder and is not specified as to each class of security pursuant to General Instruction II.D. of Form S-3 under the Securities Act of 1933, as amended.

THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(a), MAY DETERMINE.

 

(1)


PursuantTHE INFORMATION CONTAINED IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND IS NOT SOLICITING AN OFFER TO BUY THESE SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

SUBJECT TO COMPLETION, DATED MARCH 12, 2021

PROSPECTUS

Aspen Aerogels, Inc.

$250,000,000

COMMON STOCK

PREFERRED STOCK

DEBT SECURITIES

WARRANTS

RIGHTS

UNITS

This prospectus will allow us to Rule 416 of the Securities Act of 1933, as amended, this Registration Statement shall also cover any additional shares of the Registrant’s common stock that become issuable by reason of any stock dividend, stock split, recapitalizationissue, from time to time at prices and on terms to be determined at or other similar transaction effected without receipt of consideration that increases the number of the Registrant’s outstanding shares of common stock.

(2)Estimated in accordance with Rule 457(c) solely for purposes of calculating the registration fee on the basis of the average of the high and low prices of Registrant’s common stock as reported on The New York Stock Exchange as of a date ( November 1, 2017) within five business days prior to the date of filing this Registration Statement.

The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a)time of the Securities Actoffering, up to $250,000,000 of 1933, as amended, or untilany combination of the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.


The information in this preliminary prospectus is not complete and may be changed. The selling stockholders namedsecurities described in this prospectus, either individually or in units. We may not sell thesealso offer common stock or preferred stock upon conversion of or exchange for the debt securities; common stock upon conversion of or exchange for the preferred stock; or common stock, preferred stock or debt securities untilupon the registration statement filed withexercise of warrants or rights.

This prospectus describes the Securities and Exchange Commission is effective. This preliminary prospectus is not an offer to sellgeneral terms of these securities and the selling stockholders namedgeneral manner in which these securities will be offered. We will provide you with the specific terms of any offering in one or more supplements to this prospectus. The prospectus supplements will also describe the specific manner in which these securities will be offered and may also supplement, update or amend information contained in this document. You should read this prospectus and any prospectus supplement, as well as any documents incorporated by reference into this prospectus or any prospectus supplement, carefully before you invest.

Our securities may be sold directly by us to you, through agents designated from time to time or to or through underwriters or dealers. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus are not soliciting an offer to buy these securities in any state or other jurisdiction where the offer or sale is not permitted.

Subject to completion, dated November 7, 2017

PROSPECTUS

6,620,452 Shares of Common Stock

This prospectus relates to the offering and resale by the selling stockholders identified herein of up to 6,620,452 shares of our common stock, par value $0.00001 per share. These shares were issued to the selling stockholders by Aspen Aerogels, Inc. (“Aspen,” “we,” “us” or the “Company”) principally upon conversion of their shares of convertible preferred stock and convertible promissory notes into common stock in connection with our initial public offering of common stock in June 2014 (the “IPO”) or were purchased by certain of those selling stockholders in the IPO.  In addition, certain of these shares were issued to members of our board of directors at the time of the IPO as compensation for their service as directors. Weapplicable prospectus supplement. If any underwriters or agents are registering the resale of the shares issued upon conversion of convertible preferred stock and convertible promissory notes as required by the Sixth Amended and Restated Registration Rights Agreement that we entered into with the investors named therein, dated as of June 11, 2012, as amended (the “Registration Rights Agreement”). We will not receive any proceeds frominvolved in the sale of these shares byour securities with respect to which this prospectus is being delivered, the selling stockholders. The selling stockholders may sell the shares asnames of such underwriters or agents and any applicable fees, commissions or discounts and over-allotment options will be set forth herein under “Plan of Distribution.” Forin a list of the selling stockholders, see the section entitled “Selling Stockholders” on page 11. To the extent required by the Registration Rights Agreement, we have borne and will continue to bear the costs relatingprospectus supplement. The price to the registrationpublic of these shares.such securities and the net proceeds that we expect to receive from such sale will also be set forth in a prospectus supplement.

Our common stock is listed on Thethe New York Stock Exchange, (the “NYSE”)or NYSE, under the symbol “ASPN.” On November 1, 2017,March 11, 2021, the last reported sale price of our common stock on the NYSE was $4.46$22.80 per share. The selling stockholders may sell allapplicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on any securities market or a portionother securities exchange of their shares through public or private transactions at prevailingthe securities covered by the prospectus supplement. Prospective purchasers of our securities are urged to obtain current information as to the market prices or at privately negotiated prices.

We may amend or supplement this prospectus from time to time by filing amendments or supplements as required. You should read the entire prospectus and any amendments or supplements carefully before you make your investment decision.

We are an “emerging growth company” as defined under the federalof our securities, laws, and, as such, are eligible for reduced public company reporting requirements. See “Prospectus Summary—Implications of Being an Emerging Growth Company.”where applicable.

 

Investment

Investing in our common stocksecurities involves risks.a high degree of risk. See “Risk Factors beginning on page 76 of this prospectus. We may include additional risk factors in an applicable prospectus supplement under the heading “Risk Factors.” You should review that section of the prospectus supplement for a discussion of matters that investors in our securities should consider.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacydetermined if this prospectus is truthful or accuracy of this prospectus.complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is                 ____________, 2017, 2021.



TABLE OF CONTENTS

 

ABOUT THIS PROSPECTUS

1

1

PROSPECTUS SUMMARY

1

2

THE OFFERING

6

RISK FACTORS

7

6

CAUTIONARY STATEMENTSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

8

7

USE OF PROCEEDS

10

10

SELLING STOCKHOLDERS

11

PLAN OF DISTRIBUTION

13

11

DESCRIPTION OF CAPITALCOMMON STOCK

15

13

DESCRIPTION OF PREFERRED STOCK

15

DESCRIPTION OF DEBT SECURITIES

17

DESCRIPTION OF WARRANTS

23

DESCRIPTION OF RIGHTS

25

DESCRIPTION OF UNITS

27

CERTAIN PROVISIONS OF DELAWARE LAW AND OF THE COMPANY’S AMENDED AND RESTATED CERTIFICATE OF INCORPORATION AND BYLAWS

29

LEGAL MATTERS

19

33

EXPERTS

19

33

WHERE YOU CAN FIND MORE INFORMATION

19

33

INFORMATION INCORPORATEDINCORPORATION OF DOCUMENTS BY REFERENCE

34

PART II INFORMATION NOT REQUIRED IN PROSPECTUS

20

36

 

i



ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, utilizing a “shelf” registration process. Under this shelf registration process, we may offer shares of our common stock and preferred stock, various series of debt securities and/or warrants or rights to purchase any of such securities, either individually or in units, in one or more offerings, with a total value of up to $250,000,000. This prospectus provides you with a general description of the securities we may offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering.

This prospectus does not contain all of the information included in the registration statement. For a more complete understanding of the offering of the securities, you should refer to the registration statement, including its exhibits. The prospectus supplement may also add, update or change information contained or incorporated by reference in this prospectus. However, no prospectus supplement will offer a security that is not registered and described in this prospectus at the time of its effectiveness. This prospectus, together with the applicable prospectus supplements and the documents incorporated by reference into this prospectus, includes all material information relating to the offering of securities under this prospectus. You should carefully read this prospectus, the applicable prospectus supplement, the information and documents incorporated herein by reference and the additional information under the heading “Where You Can Find More Information” before making an investment decision.

You should rely only on the information contained in this prospectus,we have provided or incorporated by reference in this prospectus or contained in any prospectus supplement or free writing prospectus filed with the Securities and Exchange Commission. Neither we nor the selling stockholderssupplement. We have not authorized anyone to provide you with additional information or information different from that contained in this prospectus or incorporated by reference in this prospectus. The selling stockholders are offeringNo dealer, salesperson or other person is authorized to give any information or to represent anything not contained or incorporated by reference in this prospectus. You must not rely on any unauthorized information or representation. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and seeking offers to buy, shares of our common stock only in jurisdictions where offers and sales are permitted. Theit is lawful to do so. You should assume that the information contained in this prospectus or any prospectus supplement is accurate only as of the date of this prospectus, regardlesson the front of the time of delivery of this prospectus or ofdocument and that any sale of shares of our common stock, and the information we have incorporated herein by reference in this prospectus is accurate only as of the date of the document incorporated by reference. Our business, financial condition, resultsreference, regardless of operations and prospects may have changed since such dates. You should read boththe time of delivery of this prospectus or any sale of a security.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference in the accompanying prospectus supplement together with additional information underwere made solely for the headings “Where You Can Find More Information”benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and “Information Incorporatedshould not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

This prospectus may not be used to consummate sales of our securities, unless it is accompanied by Reference.”a prospectus supplement. To the extent there are inconsistencies between any prospectus supplement, this prospectus and any documents incorporated by reference, the document with the most recent date will control.

For investors outside the United States: Neither we nor the selling stockholders have done anything that would permit this offering or possession or distribution of this prospectus in any jurisdiction where action for that purpose is required, other than in the United States. Persons outside the United States who come into possession of this prospectus must inform themselves about, and observe any restrictions relating to, the offering of the shares of common stock and the distribution of this prospectus outside the United States.


PROSPECTUS SUMMARY

The following summary highlights selected information contained elsewhere in this prospectus or incorporated by reference in this prospectus. This summary is not complete and does not contain all the information that should be considered before investing in our common stock. Before making an investment decision, investors should carefully read the entire prospectus, and the information incorporated by reference in this prospectus paying particular attention to the risks referred to under the headings “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” and our financial statements and the notes to those financial statements that are incorporated by reference in this prospectus.

As used in this prospectus, unlessUnless the context requires otherwise the terms “Company,required, “Aspen Aerogels,” “the Company,” “we,” “us,” “our” and “us”similar terms refer to Aspen Aerogels, Inc. and its subsidiaries.

PROSPECTUS SUMMARY

The following is a summary of what we believe to be the most important aspects of our subsidiaries.business and the offering of our securities under this prospectus. We urge you to read this entire prospectus, including the more detailed consolidated financial statements, notes to the consolidated financial statements and other information incorporated by reference from our other filings with the SEC or included in any applicable prospectus supplement. Investing in our securities involves risks. Therefore, carefully consider the risk factors set forth on page 4 of this prospectus and in any prospectus supplements and in our most recent annual and quarterly filings with the SEC, as well as other information in this prospectus and any prospectus supplements and the documents incorporated by reference herein or therein, before purchasing our securities. Each of the risk factors could adversely affect our business, operating results and financial condition, as well as adversely affect the value of an investment in our securities.

Overview

Aspen Aerogels, Inc. is an aerogel technology company that designs, develops and manufactures innovative, high-performance aerogel insulation used primarily in the energy infrastructure and building materials markets. The Company has also developed a high-potential line of aerogel thermal barriers that enable solutions to thermal runaway challenges in lithium-ion batteries used in the electric vehicle market. In addition, the Company conducts research and development related to aerogel technology supported by funding from several agencies of the U.S. government and other institutions. The Company has decided to cease efforts to secure additional funded research contracts and to wind down existing contract research activities. When used in this report, the terms “we,” “us,” “our” and “the Company” refer to Aspen Aerogels, Inc. and its subsidiaries.

We design, develop and manufacture innovative, high-performance aerogel insulation used primarily in the energy infrastructure and building materials markets. We believe our aerogel blankets deliver the best thermal performance of any widely used insulation product available on the market today and provide a combination of performance attributes unmatched by traditional insulation materials. Our end-use customers select our products where thermal performance is critical and to save money, reduce energy use,improve resource efficiency, enhance sustainability, preserve operating assets and protect workers.

Our technologically advanced insulation products are targeted at the estimated $3.1 billion annual global market for energy infrastructure insulation materials. Our aerogel insulation has undergone rigorous technical validation and is used by many of the world’s largest oil producers and the owners and operators of refineries, petrochemical plants, liquefied natural gas facilities and power generating and distribution assets, such as ExxonMobil, Reliance Industries, PTT LNG, and otherRoyal Dutch Shell. Our products replace traditional insulation in existing facilities during regular maintenance, upgrades and capacity expansions. In addition, our aerogel products are increasingly being specified for use in new-build energy infrastructure. Ourinfrastructure facilities.

We introduced our two key aerogel insulation product lines for the energy infrastructure market, Pyrogel and Cryogel, product linesin 2008. Pyrogel and Cryogel have undergone rigorous technical validation by industry leading end-users and achieved significant market adoption. Our product revenue has grown from $17.2 million in 2008 to $99.8 million in 2020, representing a twelve-year compound annual growth rate of 16%. During this period, we have sold nearly $1.1 billion of our products globally, representing an installed base of more than 382 million square feet of insulation. We believe that our twelve-year track record of success positions us for future growth and continued gain in market share in the energy infrastructure market.

We have grown our business by forming technical and commercial relationships with industry leaders, which has allowed us to optimize our products to meet the particular demands of targeted market sectors. We have benefited from our technical and commercial relationships with ExxonMobil in the oil refinery and petrochemical sector, with TechnipFMC in the offshore oil sector and with BASF in the building materials market. We will continue our strategy of working with innovative companies to target and penetrate additional opportunities in the energy infrastructure and building materials markets.

We are also actively developing a number of promising aerogel products and technologies for the electric vehicle market. We have developed and are commercializing our proprietary line of PyroThin thermal barriers for use in lithium-ion batteries in electric vehicles. Our PyroThin product is an ultra-thin, lightweight and flexible thermal barrier engineered to meet the safety and performance demands of electric vehicle manufacturers. These thermal barriers are designed to impede the propagation of thermal runaway both at the battery cell and battery pack levels across multiple lithium-ion battery system architectures. Our technology offers a unique combination of performance attributes that enable electric vehicle manufacturers to achieve critical safety goals without sacrificing driving range.

In addition, we are seeking to leverage our patented carbon aerogel technology to develop industry-leading battery materials for lithium-ion battery systems in electric vehicles. These silicon-rich, carbon aerogel materials have the potential for use as a drop-in replacement for graphite in the anode of lithium-ion batteries to enable an increase in the drive range of electric vehicles.

The commercial potential for our PyroThin products and carbon aerogel materials in the electric vehicle market is significant and is likely to require us to hire additional personnel, incur additional operating expenses and incur capital expenditures to expand our manufacturing capacity, build an automated fabrication operation, and meet automotive quality system requirements, among other items.

We also derive product revenue from the building materials and other end markets. Customers in these markets use our products for applications as diverse as wall systems, military and commercial aircraft, trains, buses, appliances, apparel, footwear and outdoor gear. As we continue to enhance our aerogel technology platform, we believe we will have additional opportunities to address high value applications in the global insulation market, the electric vehicle market and in a number of new, high-value markets.

We generate product revenue throughOur patented aerogel products and manufacturing technologies are significant assets. Silica aerogels are complex structures in which 97% of the salevolume consists of air trapped between intertwined clusters of amorphous silica solids. These extremely low-density solids provide superior thermal and acoustic insulating properties. Although silica aerogels are usually fragile materials, we have developed innovative and proprietary manufacturing processes that enable us to produce industrially robust aerogel insulation cost-effectively and at commercial scale. Our electrically conductive carbon aerogel materials are reaching development maturity, expanding our market opportunities in energy storage, filtration, water purification, and gas sorption. These patented carbon aerogels are uniquely strong, providing the physical strength, charge and ion conductivity, and porosity required to host high concentrations of silicon in lithium-ion battery anodes. These silicon carbon aerogels have the potential to lower the costs and increase the energy density of electric vehicle battery systems.

Our insulation products help customers to improve the resource efficiency and sustainability of their operations. These products enable compact system design, reduce installation time and costs, promote freight and logistics cost savings, reduce system weight, minimize required storage space and enhance job site safety. Our insulation products reduce the incidence of corrosion under insulation, which is a significant maintenance cost and safety issue in energy infrastructure facilities. Many of our lineinsulation products also offer strong fire protection, which is a critical performance requirement in our markets. We believe our array of aerogel blankets. We market and sell our products primarily through a sales force based in North America, Europe and Asia. The effortsproduct attributes provides strong competitive advantages over traditional insulation. Although competing insulation materials may have one or more comparable attributes, we believe that no single insulation material currently available offers all of our sales force are supported by a small number of sales consultants with extensive knowledge of a particular market or region. Our sales force is responsible for establishing and maintaining customer and partner relationships, delivering highly technical information and ensuring high-quality customer service.

Our salespeople work directly with end-use customers and engineering firms to promote the qualification, specification and acceptance of our products. We also rely on an existing and well-established channel of qualified insulation distributors and contractors in more than 30 countries around the world to ensure rapid delivery of our products and strong end-user support. Our salespeople also work to educate insulation contractors about the technical and operating cost advantagesproperties of our aerogel blankets.insulation products.

Our aerogel thermal barrier products enable our customers to enhance the safety and performance of their lithium-ion battery systems. These barriers are designed to impede the propagation of thermal runaway in lithium-ion battery systems both at the battery cell and battery pack level across multiple lithium-ion battery system architectures. Our ultra-thin, lightweight and flexible thermal barriers allow battery manufacturers to achieve critical safety goals without sacrificing energy density. We also perform research services under contracts with various agenciesbelieve we offer the best available technology in the management of thermal runaway in the U.S. government, includingelectric vehicle market.

Impact of COVID-19

With regard to the Department of DefenseCOVID-19 pandemic, we have implemented and the Department of Energy,are following safe practices recommended by public health authorities and other institutions. Research performed under contractgovernment entities. We will continue to focus on the safety and health of our employees, customers and vendors. We have implemented various precautionary measures, including remote work arrangements, restricted business travel and procedures for social distancing, face coverings and safe hygiene. We continue to monitor public health guidance as it evolves and plan to adapt our practices as appropriate. Refer to the section below entitled “Item 1A. Risk Factors” for more information concerning risks to our business associated with government agencies and other institutions enables us to develop and leverage technologies into broader commercial applications.COVID-19.

We manufacture our products using our proprietary technology at our facility in East Providence, Rhode Island. We completed the construction and start-up of a third production line inhave operated the East Providence facility during 2015, whichsince 2008 and have increased our annual nameplate capacity in phases through December 31, 2020 to approximately 5055 million square feet of aerogel blankets. DuringWe are currently engaged in an initiative, which we refer to as EP20, designed to increase the first quartercapacity of 2016,the East Providence facility to 60 million square feet of aerogel blankets by the end of 2021. In addition, we announcedanticipate that we will need to construct a state-of-the-art thermal barrier fabrication operation, hire dedicated thermal barrier fabrication employees, and increase our aerogel blanket manufacturing capacity to keep pace with the planned construction of a second manufacturing facility in Statesboro, Georgia supported by a package of incentivessignificant potential demand for our PyroThin thermal barriers from the State of Georgia and local governmental authorities. We have elected to delay construction of this facility to better align the capacity expansion with our assessment of future demand.

1


During 2016,electric vehicle market. Accordingly, we entered into a strategic partnership with BASF SE to develop and commercialize products for the building materials and other markets. The strategic partnership included a supply agreement governing the sale of our Spaceloft A2 product to BASF and a joint development agreement targeting innovative products and technologies. Subject to certain preconditions, BASF also agreed to make a series of prepayments to usare in the aggregateearly stages of $22 million during the construction of our planned manufacturing facility in Statesboro, Georgia. The prepayments will be either credited against amounts invoiced to BASF for Spaceloft A2 or repaid by us to BASF after December 31, 2023. Asplanning a result of our decision to delay construction of the Statesboro facility, we have yet to fulfill the preconditions, and commencement of the prepayments from BASF will be delayed until the preconditions are satisfied.

In July 2017, we announced the launch of a new product, Pyrogel® HPS, a high-temperature aerogel blanket engineered to provide thermal conductivity and economic performance at service temperatures of up to 650°C (1200°F).

During 2016, we filed a complaint for patent for patent infringement principally against two China-based companies at the United States International Trade Commission (“ITC”) and the District Court in Mannheim, Germany. On September 29, 2017, the Administrative Law Judge (“ALJ”) presiding over the ITC investigation issued an Initial Determination finding that the two defendants have infringed our patents relating to aerogel insulation.  The ALJ also recommended a limited exclusion order with certification provision as a remedy to prevent the importation of infringing aerogel products into the United States.  Respondents have petitioned the ITC for a review of the ALJ’s Initial Determination and a final determination on the violation and remedy is expected from the full ITC commission by January 29, 2018, which final determination will determine whether or not a limited exclusion order will be issued.  In the event that a limited exclusion order is issued, the order is subject to a 60-day presidential review period.  Upon request by a party, the final determination may be appealed to the United States Court of Appeals for the Federal Circuit. The German litigation remains ongoing.

Our revenue for the nine months ended September 30, 2017 was $75.3 million, which represented a decrease of $14.8 million from the nine months ended September 30, 2016. Net loss for the nine months ended September 30, 2017 was $17.6 million and net loss per diluted share was $0.76. Net loss for the nine months ended September 30, 2016 was $6.3 million and net loss per diluted share was $0.27.

Risks Relating to Our Business

We are an aerogel technology company, and our business and ability to execute our business strategy are subject to a number of significant risks of which you should be aware before you decide to buy shares of our common stock. Among these important risks are the following:

We have incurred annual net losses since our inception, and we may continue to incur net losses in the future and may never reach profitability.

We have yet to achieve positive total cash flow, and our ability to generate positive cash flow is uncertain.

We are dependent on a single manufacturing facility. Any significant disruption to this facility or the failure of any of our three production lines in this facility to operate according to our expectation could have a material adverse effect on our business and results of operations.

We will require significant additional capital to pursue our growth strategy, but we may not be able to obtain additional financing on acceptable terms or at all.

A sustained downturn in the energy industry, due to lower oil and gas prices or reduced energy demand, could decrease demand for some of our products and services, which could have a material adverse effect on our business, financial condition and results of operations.

Shortages of the raw materials used in the production of our products, increases in the cost of such materials or disruptions in our supply chain could adversely impact our financial condition and results of operations.

2


The market for insulation products incorporating aerogel blankets is relatively undeveloped and our products may never be widely adopted, which would have a material adverse effect on our business.

Our products are expensive relative to other insulation products, which could make it more difficult for us to grow our revenue and achieve broader adoptionexpansion of our aerogel products.

The insulation market we serve is highly competitive; if we are unable to compete successfully, we may not be able to increase or maintain our market share and revenues.

From time to time we have had difficulty consistently producing product that meets applicable product specifications and technical and delivery requirements, and such difficulties could expose us to financial, contractual or other liabilities.

If the expected growth in the demand for our products does not follow each of our planned capacity expansions, then our business will be materially adversely affected.

If we fail to achieve the increase in production capacity that our continued growth requires in a timely manner, or at all, our growth may be hindered and our business or results of operations may be materially adversely affected.

A substantial portion of our revenue comes from sales in foreign countries and we may expand our operations outside of the United States, which subjects us to increased economic, trade, foreign exchange, operational and political risks that could adversely impact our business, financial conditions and results of operations and also increase our costs and make it difficult for us to operate profitably.

We rely on sales to a limited number of direct customers, including distributors, contractors, OEMs, partners and end-use customers for the substantial majority of our revenue, and the loss of one or more significant direct customers or several of our smaller direct customers could materially harm our business. In addition, we understand from our direct customers that a substantial majority of their sales of our products are to a small number of end-use customers and the loss of one or more significant end-use customers or several of our smaller end-use customers could materially harm our business.

Negative perceptions regarding the safety, quality or other attributes of our products or a failure or a perceived failure of our products could have a material adverse effect on our results of operations and could make us unable to continue our business.

Failure by us to develop, maintain and strengthen strategic relationships with industry leaders to commercialize our products, particularly in the building materials market, may adversely affect our results of operations and our ability to grow our business.

Our revenue may fluctuate, which may result in a high degree of variability in our results of operations and make it difficult for us to plan based on our future outlook and to forecast our future performance.

Our results of operations could be adversely affected if our operating expenses incurred do not correspond with the timing of our revenues.

We are exposed to the credit risk of some of our direct customers, including distributors, contractors and OEMs, which subjects us to the risk of non-payment for our products.

Our working capital requirements involve estimates based on demand and production expectations and may decrease or increase beyond those currently anticipated, which could harm our results of operations and financial condition.

If we lose key personnel upon whom we are dependent, or if we are unable to successfully recruit and retain skilled employees, we may not be able to manage our operations and meet our strategic objectives.

Our inability to protect our intellectual property rights could negatively affect our business and results of operations.

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We have initiated intellectual property litigation that is costly, and could limit or invalidate our intellectual property rights, divert time and efforts away from business operations, require us to pay damages and/or costs and expenses and/or otherwise have an adverse material impact on our business, and we could become subject to additional such intellectual property litigation in the future.

We expect that the price of our common stock will fluctuate substantially, which could subject us to securities class action litigation and result in substantial losses to our stockholders.

For additional information about the risks we face, please see the section of this prospectus entitled “Risk Factors.”

Implications of Being an Emerging Growth Company

As a company with less than $1.0 billion in revenue during our last fiscal year, we qualify as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act, or JOBS Act, enacted in April 2012. An emerging growth company may take advantage of reduced reporting requirements that are otherwise applicable to public companies. These provisions include, but are not limited to:

not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act of 2002, or Sarbanes-Oxley Act;

reduced disclosure obligations regarding executive compensation in our periodic reports, proxy statements and registration statements; and

exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and stockholder approval of any golden parachute payments not previously approved.

We may take advantage of these provisions for up to five years after the first sale of our common equity securities pursuant to an effective registration statement under the Securities Act of 1933, as amended, or the Securities Act. Our first registration statement filed under the Securities Act became effective on June 12, 2014. However, if certain events occur prior to the end of such five year period, including if we become2023. The expected elements of the completed expansion plan will include the size of the required capacity expansion, the selection of an optimal manufacturing site for the expansion, the appropriate financing structure to fund the project fully and a “large accelerated filer,”detailed timeline for the construction and operation of the facility.

Additional Information

For additional information related to our annual gross revenues exceed $1.07 billion or we issue more than $1 billion of non-convertible debt in any three year period, we would cease to be an emerging growth company priorbusiness and operations, please refer to the endreports incorporated herein by reference, including our Annual Report on Form 10-K for the year ended December 31, 2020 and subsequent reports filed with the SEC, as described under the caption “Incorporation of such five year period.

We may choose to take advantage of some but not all of these reduced burdens. We have taken advantage of certain of the reduced disclosure obligations, which include providing reduced executive compensation disclosure in our periodic reports, proxy statements and registration statements, and may elect to take advantage of other reduced burdens in future filings. As a result, the information that we provide to our stockholders may be different than you might receive from other public reporting companies in which you hold equity interests.

Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards until such time as those standards apply to private companies. However, we have irrevocably elected not to avail ourselvesDocuments by Reference” on page 18 of this extended transition period for complying with new or revised accounting standards and, therefore, we will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.prospectus.

Our Corporate Information

We are a corporation organized under the laws of Delaware. In June 2008, we completed a reorganization pursuant to which our predecessor company merged with and into a newly formed Delaware corporation, renamed Aspen Aerogels, Inc. We own three wholly owned subsidiaries: Aspen Aerogels Rhode Island, LLC, Aspen Aerogels Germany, GmbH and Aspen Aerogels Georgia, LLC. We maintain our corporate offices in Northborough, Massachusetts.

Our corporate headquarters areprincipal office is located at 30 Forbes Road, Building B, Northborough, Massachusetts 01532, and our telephone number is (508) 691-1111. Our website address is https://www.aerogel.com. The information contained on, or that can be accessed through, our website is not a part of this prospectus. We maintain ahave included our website ataddress in this prospectus solely as an inactive textual reference.

Our Annual Reports on Form http://www.aerogel.com10-K,, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and all amendments to which we regularly post copiesthose reports filed or furnished pursuant to Section 13(a) or 15(d) of our press releases as well as additional information about us. Our filings with the Securities and Exchange Commission, or SEC, will beAct are available free of charge through the investor relations page of our internet website as soon as

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reasonably practicable after beingwe electronically filedfile such material with, or furnishedfurnish it to, the SEC.Information contained in our website does not constitute a part of this prospectus or our other filings with the SEC.

All brand names or trademarks appearing in this prospectus are the property of their respective holders. Use or display by us of other parties’ trademarks, trade dress, or products in this prospectus is not intended to, and does not, imply a relationship with, or endorsements or sponsorship of, us by the trademark or trade dress owners.

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trademark.

THE OFFERINGOfferings Under This Prospectus

Common stock offered by selling stockholders

6,620,452 shares

Common stock outstanding

23,637,115 shares

Use of proceeds

We will not receive any proceeds from the sale of the shares of common stock offered by the selling stockholders.

Offering price

The selling stockholders may sell all or a portion of their shares through public or private transactions at prevailing market prices or at privately negotiated prices.

Risk factors

You should read the “Risk Factors” section of this prospectus for a discussion of factors to consider carefully before deciding to invest in shares of our common stock.

New York Stock Exchange symbol

ASPN

The number of shares of common stock outstanding is based on an aggregate of 23,637,115 shares outstanding as of November 1, 2017, and excludes:

2,444,055 shares of common stock issuable upon exercise of outstanding options as of November 1, 2017, at a weighted average exercise price of $7.63 per share, of which 1,152,433 shares were vested as of such date;

834,859 shares of common stock issuable upon vesting of restricted stock units outstanding as of November 1, 2017;

120 shares of common stock issuable upon the exercise of warrants to purchase our common stock outstanding as of November 1, 2017, at a weighted-average exercise price of $8.25 per share; and

2,391,406Under this prospectus, we may offer shares of our common stock and preferred stock, various series of debt securities and/or warrants or rights to purchase any of such securities, either individually or in units, with a total value of up to $250,000,000, from time to time at prices and on terms to be determined by market conditions at the time of the offering. This prospectus provides you with a general description of the securities we may

offer. Each time we offer a type or series of securities under this prospectus, we will provide a prospectus supplement that will describe the specific amounts, prices and other important terms of the securities, including, to the extent applicable:

designation or classification;

aggregate principal amount or aggregate offering price;

maturity, if applicable;

rates and times of payment of interest or dividends, if any;

redemption, conversion or sinking fund terms, if any;

voting or other rights, if any; and

conversion or exercise prices, if any.

The prospectus supplement also may add, update or change information contained in this prospectus or in documents we have incorporated by reference into this prospectus. However, no prospectus supplement will fundamentally change the terms that are available for future issuance underset forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

We may sell the securities directly to investors or to or through agents, underwriters or dealers. We, and our 2014 equity incentive plan.agents or underwriters, reserve the right to accept or reject all or part of any proposed purchase of securities. If we offer securities through agents or underwriters, we will include in the applicable prospectus supplement:

the names of those agents or underwriters;

 

applicable fees, discounts and commissions to be paid to them;

 


details regarding over-allotment options, if any; and

the net proceeds to us.

This prospectus may not be used to consummate a sale of any securities unless it is accompanied by a prospectus supplement.

RISK FACTORS

Investing in our common stocksecurities involves significant risk. The prospectus supplement applicable to each offering of our securities will contain a high degreediscussion of risk. Youthe risks applicable to an investment in Aspen Aerogels, Inc. Prior to making a decision about investing in our securities, you should carefully consider the risks and uncertainties andspecific factors discussed under the heading “Risk Factors” in the applicable prospectus supplement, together with all of the other information documentscontained or reports includedincorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus and, if applicable, any prospectus supplement or other offering materials, includingprospectus. You should also consider the risks, uncertainties and uncertaintiesassumptions discussed under the heading “Risk Factors” included in our most recent Annual Reportannual report on Form 10-K, as revised or supplemented by our subsequent quarterly reports on Form 10-Q or our current reports on Form 8-K that we have filed with the SEC, all of which are incorporated herein by reference, in this prospectus, and any updates to those risk factors includedwhich may be amended, supplemented or superseded from time to time in our periodic and currentby other reports filedwe file with the SEC in the future. The risks and incorporated by reference in this prospectus. Our business, financial conditionuncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or resultsthat we currently deem immaterial may also affect our operations. The occurrence of operations could be harmed by any of these risks. As a result,risks might cause you couldto lose someall or allpart of your investment in our common stock. Additional risks not currently known to us or other factors not perceived by us to present significant risks to our business at this time also may impair our business operations.the offered securities.


CAUTIONARY STATEMENTSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSTATEMENTS

The SEC, encourages companies to disclose forward-looking information so that investors can better understand a company’s future prospects and make informed investment decisions. This prospectus and the documents incorporated by reference in this prospectus include forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, that relate to future events or our future financial performance andAct. These statements involve known and unknown risks, uncertainties and other important factors thatwhich may cause our actual results, levels of activity, performance or achievements to differbe materially different from any future results, levels of activity, performanceperformances or achievements expressed or implied by thesethe forward-looking statements. Words such as,Forward-looking statements include, but are not limited to, “believe,” “expect,” “anticipate,” “estimate,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “targets,” “likely,” “will,” “would,” “could,” “should,” “continue,”statements about: the expected future growth of the market for our aerogel insulation and similar expressionsour continued gain in market share, in particular in the energy infrastructure insulation market and other markets we target; our expectation that our investment in incremental manufacturing and operating expense will sustain long-term growth in our existing markets and develop new business opportunities; our plans to continue to develop and optimize aerogel products for high-value applications within the building materials market and our plan to realize revenue from this market; our plans to develop and optimize aerogel products for potential commercialization within the electric vehicle market, including our program to optimize carbon aerogels to improve the performance and cost of lithium-ion batteries and our initiative to optimize our silica aerogel products to inhibit the spread of thermal runaway related battery fires in electric vehicles; our plans and expectations to partner with industry leaders in the battery and electric vehicle market or phrases,such partnerships resulting in products and technologies or otherwise in meaningful financial results; our pursuit of high-value opportunities for our aerogel products within different segments of the negativeglobal insulation market, including the building materials market, and our plans to leverage our aerogel technology platform to develop innovative, aerogel enhanced products for applications in new markets, including the electric vehicle market; our plans to focus additional resources to continue to grow our share of those expressionsthe energy infrastructure insulation market; our pursuit of and the expected greater adoption of our products in the LNG and power generation markets and our expectation that product revenue will be generated in large part by demand for insulation associated with scheduled plant shutdowns, or phrases, are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Although we believeturnarounds, and other maintenance-related projects; our expectation that our products will be specified during the design phase in a growing number of new plant construction and capital expansion projects and our expectation that we will have a reasonable basisan increasing percentage of our products sold for each forward-looking statement containeduse in this prospectuscapital projects; our expectation that the growth in global energy demand will result in increased new-build and incorporated by reference in this prospectus, we caution you that these statements are based onlarge capacity expansion projects, driving demand for our projectionsaerogel products; our plans to continue our strategy of working with innovative companies to target and penetrate additional market opportunities; our plans to develop strategic partnerships to facilitate market penetration beyond the future that are subject to knownenergy infrastructure and unknown risks and uncertainties and other factors that may cause our actual results, level of activity, performance or achievements expressed or implied by these forward-looking statements, to differ. The sections in our periodic reports, including our Annual Report on Form 10-K for the fiscal year ended December 31, 2016, entitled “Business,” “Risk Factors,” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations”building materials market, as well as other sectionsthe expected goals and priorities of such strategic partnerships; our belief that an adequate long-term supply of silica-precursor is available and our plans to reduce reliance on precursors susceptible to significant price fluctuations; our expectation in this prospectusour ability to implement lower cost product formulations and the documents or reports incorporated by reference in this prospectus, discuss somerealize material purchasing efficiencies; our belief that our portfolio of the factors that could contributepatents, trade secrets and know-how present a significant barrier to these differences. These forward-looking statements include, among other things, statements about:

our beliefspotential new entrants in the appropriatenessproduction of aerogel blanket insulation; our assumptions, the accuracy ofexpectation that we will be successful in enforcing and defending our estimates regarding expenses, loss contingencies, future revenues, future profits, uses of cash, available credit, capital requirements,patents against competitors and the need for additional financing;

that such patents are valid and enforceable, as well as our expectations about revenue, expenses, Adjusted EBITDA, GAAP EPS, cash balancesthe costs and related variationsconsequences of our current or trends; beliefs aboutpotential future patent litigation and the general strengthpotential for additional patent litigation; our belief that our products possess strong competitive advantages over traditional insulation materials, including the superior thermal performance and the thin, easy-to-use and durable blanket form of our products; our plans to expand capacity at our East Providence, Rhode Island manufacturing facility; our expectation that expanded capacity in our East Providence, Rhode Island facility will become available or healthoperational in a timely manner to support the long-term growth in demand we expect; our expectation that the completion of Aspen Aerogels’ business; the performanceproject to expand capacity in our East Providence, Rhode Island facility will provide an additional annual nameplate capacity of our5 million square feet of aerogel blankets; our plans to construct a secondbelief that we can finance the expansion of our existing manufacturing facility with anticipated available credit, cash flows from operations, debt financings, technology licensing agreements, customer prepayments or equity financings; our belief that our end-use customers will continue to invest in Statesboro, Georgia;major energy infrastructure projects; our estimates of annual production capacity;expectation that we will continue to sell our products in the building materials and other end markets; our expectation that we will develop, manufacture and sell new products and technologies

beliefs aboutthrough the strategic partnership with BASF SE and that our strategic partnership with BASF andSE will facilitate our penetration of the potential benefits of such a relationship, includingbuilding materials market; our joint development agreement with BASF SE, and the potential for it to createsupport the development and commercialization of new productaerogel products and technologies; our belief that the potential for significant technological innovation in traditional insulation materials is limited and that new high-performance materials will be required to meet evolving market opportunities;

our supply agreement with BASF, our exclusive supply to BASF of its Spaceloft® A2 product, the potential for future cash advances from BASF under the supply agreement (payment of which are subject to certain conditions) to provide a source of financing for some portion of the cost of the planned construction of our proposed manufacturing plant expected to be located in Statesboro, Georgia, and the potential for BASF to become a significant customer for our products; our joint development agreement with BASF, and the potential for it to support the development of new aerogel products and technologies;

requirements for energy efficient insulations systems; our beliefs aboutbelief that our aerogel products and manufacturing processes are proprietary and that we can protect our patents, trade secrets and know-how associated therewith; our belief that we can continue to improve the usefulness of the square foot operating metric; our beliefs about the financial metrics that are indicativecost efficiency of our core performance;

manufacturing process, that our beliefs aboutcurrent expansion plans offer attractive returns on incremental invested capital, and that we will focus our development efforts on new products and next generation technology with application in new, high value market segments; our belief that we will have opportunities to address additional high value applications in the usefulnessestimated $3.1 billion global insulation market, and that we are well positioned to leverage a decade’s worth of research and development to design and commercialize disruptive aerogel products for a wide array of new markets; our belief that our products have the lowest cost on a fully-installed basis or offer significant life-cycle cost savings in energy infrastructure and certain other applications as compared to traditional insulation materials; our plans to continue to expand our global sales force and distribution network to support anticipated growth in customers and demand for our products and our plans to seek to promote greater enterprise-wide utilization of our presentationproducts by existing end-use customers; our belief that revenue growth will moderate due to a decrease in project-based demand in the subsea market and little to no growth in project-based demand in the LNG market; our expectations and projections about future revenues, revenue growth, costs, expenses, production volumes, manufacturing productivity, gross profit, profitability, net loss, loss per share and Adjusted EBITDA, sources and uses of Adjusted EBITDA;cash, liquidity, cash flow, capital requirements and the sufficiency of our existing cash balance and available credit; our expectations that most of our revenue will continue to come from a relatively small number of customers for the foreseeable future; our expectations of long-term revenue growth, with increasing levels of gross profit and improved cash flows from operations and our expectations that we will incur significant capital expenditures related to the expansion of our manufacturing capacity to support this expected long-term growth in demand; our expectation to continue to increase investment in research and development in our efforts to enhance and expand our aerogel technology platform; our expectations about the effectimpact of manufacturing capacitynew accounting pronouncements on our consolidated financial metrics such as Adjusted EBITDA;

statements and related disclosures; our beliefs aboutbelief that our experienced and dedicated leadership team will provide us with a competitive advantage in the outcome, effects or estimated costs of current or future litigation or their respective timing, including in connection with the Company’s patent enforcement actions;

industry; our beliefs about the validitybelief of our patents, our expectations abouttechnological and market leadership in aerogels; the outcome and timing of the patent enforcement actions; our expectations about hiring additional personnel;

our plans to devote substantial resources to theexpected future development of new aerogel technology;

technologies; and our expectations about product mix;limitations of net operating losses.


our expectations about future material costs and manufacturing expenses as a percentage of revenue;

ourWords such as “may,” “will,” “anticipate,” “estimate,” “expects,” “projects,” “intends,” “plans,” “believes” and words and terms of similar substance used in connection with any discussion of future operating or financial performance, identify forward-looking statements. All forward-looking statements are management’s present expectations of future gross profitevents and the effectare subject to a number of manufacturing expenses, manufacturing capacityrisks and productivity on gross profit;

our expectations about our resources and other investments in new technology and related research and development activities and associated expenses;

our expectations about short and long term (a) research and development (b) general and administrative and (c) sales and marketing expenses;

our expectations of near term revenue declines; our expectations of revenue growth, increased gross profit, and improving cash flows over the long term;

our intentions about managing capital expenditures and working capital balances;

our expectations about incurring significant capital expenditures in the future; our expectations about the expansion of our workforce and resources and its effect on sales and marketing, general and administrative, and related expenses;

our expectations about future product revenue and demand for our products;

our expectations about the effect of stock based compensation on various costs and expenses;

our expectations about potential sources of future financing;

our beliefs about the impact of accounting policies on our financial statements;

our beliefs about the effect of interest rates, inflation and foreign currency fluctuations on ouruncertainties that could cause actual results of operations and financial condition; and

our beliefs about the expansion of our international operations.

We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events couldto differ materially and adversely from the plans, intentions and expectations disclosedthose described in the forward-looking statements we make.statements. We have included important cautionary statements in this prospectus or in the documents incorporated by reference in this prospectus, particularly in the “Risk Factors” section, and the risk factors incorporated by reference herein, that we believe could cause actual results or events to differ materially from the forward-looking statements that we make. OurFor a summary of such factors, please refer to the section entitled “Risk Factors” in this prospectus, as updated and supplemented by the discussion of risks and uncertainties under “Risk Factors” contained in any supplements to this prospectus and in our most recent annual report on Form 10-K, as revised or supplemented by our subsequent quarterly reports on Form 10-Q or our current reports on Form 8-K, as well as any amendments thereto, as filed with the SEC and which are incorporated herein by reference. The information contained in this document is believed to be current as of the date of this document. We do not intend to update any of the forward-looking statements do not reflectafter the potential impactdate of any future acquisitions, mergers, dispositions, joint venturesthis document to conform these statements to actual results or investments we may make.to changes in our expectations, except as required by law.

You should readIn light of these assumptions, risks and uncertainties, the results and events discussed in the forward-looking statements contained in this prospectus and the documents and reports incorporated by reference in this prospectus might not

occur. Stockholders and the documents that we reference in this prospectus and have filed as exhibitsother readers are cautioned not to place undue reliance on the registration statement of which this prospectus forms a part, completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements, contained in this prospectus are madewhich speak only as of the date of this prospectus, andor the forward-looking statements contained in anydate of the document or report incorporated by reference in this prospectusprospectus. We are made as of the dates of such documents or reports. We do not assume,under any obligation, and specificallywe expressly disclaim any obligation, to update or alter any forward-looking statements, whether as a result of new information, future events or otherwise. All subsequent forward-looking statements attributable to Aspen Aerogels, Inc. or to any person acting on its behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section.


USE OF PROCEEDS

We are filing the registration statement of which this prospectus forms a part to permit holders of the shares of our common stock described in the section entitled “Selling Stockholders” to resell such shares. Wecannot assure you that we will not receive any proceeds from the resale of any shares offered by this prospectus by the selling stockholders.


SELLING STOCKHOLDERS

This prospectus covers the resale by the selling stockholders identified below of 6,620,452 shares of our common stock. These shares were issued to the selling stockholders by Aspen Aerogels, Inc. (“Aspen,” “we,” “us” or the “Company”) principally upon conversion of their shares of convertible preferred stock and convertible promissory notes into common stock in connection with our initial public offering of common stock in June 2014 (the “IPO”) or were purchased by certain of those selling stockholderssecurities which may be offered pursuant to this prospectus. Unless otherwise indicated in the IPO.  In addition, certain of these shares were issuedapplicable prospectus supplement, we intend to members of our board of directors at the time of the IPO as compensation for their service as directors and prior to our filing of a registration statement on Form S-8 registering shares reserved for grant under our 2014 Employee, Director and Consultant Equity Incentive Plan.  We are registering the resale of the shares issued upon conversion of convertible preferred stock and convertible promissory notes as required by the Sixth Amended and Restated Registration Rights Agreement that we entered into with the investors named therein, dated as of June 11, 2012, as amended (the “Registration Rights Agreement”).  None of our selling stockholders receiveduse any of our securities as compensation for underwriting services. We will not receive anynet proceeds from the resalesale of securities under this prospectus for general corporate purposes, including, but not limited to, working capital, capital expenditures, repayment of any existing indebtedness, investments and acquisitions. We have not determined the amounts we plan to spend on any of the common stock byareas listed above or the selling stockholders.

Except as disclosedtiming of these expenditures. As a result, our management will have broad discretion to allocate the net proceeds, if any, we receive in the footnotes below, noneconnection with securities offered pursuant to this prospectus for any purpose. Pending application of the selling stockholders has been an officernet proceeds as described above, we may initially invest the net proceeds in short-term, investment-grade, interest-bearing securities or directorapply them to the reduction of ours or any of our predecessors or affiliates within the past three years. Except as disclosed in the footnotes below, no selling stockholder had a material relationship with the Company or any of its affiliates within the last three years. Except as disclosed in the footnotes below, none of the selling stockholders is affiliated with a broker dealer.short-term indebtedness.

The following table and the accompanying footnotes are based in part on information supplied to us by the selling stockholders. The table and footnotes assume that the selling stockholders will sell all of the shares listed. However, because the selling stockholders

PLAN OF DISTRIBUTION

We may sell all or some of their sharesoffer securities under this prospectus from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods. We may sell the securities (1) through underwriters or dealers, (2) through agents or (3) directly to one or more purchasers, or through a combination of such methods. We may distribute the securities from time to time in another permitted manner, we cannot assure you asone or more transactions at:

a fixed price or prices, which may be changed from time to time;

market prices prevailing at the time of sale;

prices related to the actual numberprevailing market prices; or

negotiated prices.

We may directly solicit offers to purchase the securities being offered by this prospectus. We may also designate agents to solicit offers to purchase the securities from time to time, and may enter into arrangements for “at-the-market,” equity line or similar transactions. We will name in a prospectus supplement any underwriter or agent involved in the offer or sale of shares thatthe securities.

If we utilize a dealer in the sale of the securities being offered by this prospectus, we will sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale.

If we utilize an underwriter in the sale of the securities being offered by this prospectus, we will execute an underwriting agreement with the underwriter at the time of sale, and we will provide the name of any underwriter in the prospectus supplement which the underwriter will use to make resales of the securities to the public. In connection with the sale of the securities, we, or the purchasers of the securities for whom the underwriter may act as agent, may compensate the underwriter in the form of underwriting discounts or commissions. The underwriter may sell the securities to or through dealers, and the underwriter may compensate those dealers in the form of discounts, concessions or commissions.

With respect to underwritten public offerings, negotiated transactions and block trades, we will provide in the applicable prospectus supplement information regarding any compensation we pay to underwriters, dealers or agents in connection with the offering of the securities, and any discounts, concessions or commissions allowed by underwriters to participating dealers. Underwriters, dealers and agents participating in the distribution of the securities may be deemed to be underwriters within the meaning of the Securities Act, and any discounts and commissions received by them and any profit realized by them on resale of the securities may be deemed to be underwriting discounts and commissions. We may enter into agreements to indemnify underwriters, dealers and agents against civil liabilities, including liabilities under the Securities Act, or to contribute to payments they may be required to make in respect thereof.

If so indicated in the applicable prospectus supplement, we will authorize underwriters, dealers or other persons acting as our agents to solicit offers by certain institutions to purchase securities from us pursuant to delayed delivery contracts providing for payment and delivery on the date stated in each applicable prospectus supplement. Each contract will be for an amount not less than, and the aggregate amount of securities sold pursuant to such contracts shall not be less nor more than, the respective amounts stated in each applicable prospectus supplement. Institutions with whom the contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and other institutions, but shall in all cases be subject to our approval. Delayed delivery contracts will not be subject to any conditions except that:

the purchase by an institution of the selling stockholderssecurities covered under that contract shall not at the time of delivery be prohibited under the laws of the jurisdiction to which that institution is subject; and

if the securities are also being sold to underwriters acting as principals for their own account, the underwriters shall have purchased such securities not sold for delayed delivery. The underwriters and other persons acting as our agents will not have any responsibility in respect of the validity or thatperformance of delayed delivery contracts.

One or more firms, referred to as “remarketing firms,” may also offer or sell the securities, if a prospectus supplement so indicates, in connection with a remarketing arrangement upon their purchase. Remarketing firms will be held byact as principals for their own accounts or as our agents. These remarketing firms will offer or sell the selling stockholders after completion of any sales. We do not know how long the selling stockholders will hold the shares before selling them.

Beneficial ownership is determinedsecurities in accordance with the rules and regulationsterms of the SECsecurities. Each prospectus supplement will identify and includes votingdescribe any remarketing firm and the terms of its agreement, if any, with us and will describe the remarketing firm’s compensation. Remarketing firms may be deemed to be underwriters in connection with the securities they remarket. Remarketing firms may be entitled under agreements that may be entered into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, and may be customers of, engage in transactions with or investment power with respect to our common stock. Shares of our common stock subject to options, restricted stock units or warrants that are currently exercisable or exercisable within 60 days of November 1, 2017 are considered outstanding and beneficially owned by the person holding the options, restricted stock units or warrantsperform services for the purpose of calculating the percentage ownership of that person but not for the purpose of calculating the percentage ownership of any other person. Except as otherwise notedus in the footnotes below, we believe the persons and entities in this table have sole voting and investing power with respect to allordinary course of the shares of our common stock beneficially owned by them, subject to community property laws, where applicable. The inclusion of any shares in this table does not constitute an admission of beneficial ownership by the persons named below. The beneficial owners listed below are sorted alphabetically by name.

 

Shares of Common Stock Beneficially Owned Before this Offering

 

 

Number of shares of Common Stock Being Offered

 

 

Shares of Common Stock To Be Beneficially owned Upon Completion of this Offering

 

 

Selling Stockholder

 

Number

 

 

Percentage(1)

 

 

 

 

 

Number

 

 

Percentage(1)

 

 

Contra Costa Capital, LLC(2)

 

 

510,787

 

 

 

2.2

%

 

 

510,787

 

 

 

 

 

 

 

 

GKFF Ventures I, LLC(3)

 

 

3,167,322

 

 

 

13.4

%

 

 

3,167,322

 

 

 

 

 

 

 

 

Reservoir Capital Master Fund, L.P.(4)

 

 

251,915

 

 

 

1.1

%

 

 

251,915

 

 

 

 

 

 

 

 

Reservoir Capital Partners, L.P. (5)

 

 

2,644,066

 

 

 

11.2

%

 

 

2,644,066

 

 

 

 

 

 

 

 

Robert R. Gervis(6)

 

 

211,068

 

 

*

 

 

 

7,727

 

 

 

203,341

 

 

*

 

 

Mark L. Noetzel(7)

 

 

79,838

 

 

*

 

 

 

7,727

 

 

 

72,111

 

 

*

 

 

William P. Noglows(8)

 

 

83,515

 

 

*

 

 

 

7,727

 

 

 

75,788

 

 

*

 

 

Richard R. Reilly(9)

 

 

75,894

 

 

*

 

 

 

7,727

 

 

 

68,167

 

 

*

 

 

Steven R. Mitchell(10)

 

 

63,494

 

 

*

 

 

 

7,727

 

 

 

55,767

 

 

*

 

 

P. Ramsay Battin(11)

 

 

16,935

 

 

*

 

 

 

7,727

 

 

 

9,208

 

 

*

 

 

* Less than one percent (1%).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

*

 

 

(1)

Based on a denominator equal to the sum of (i) 23,637,115 shares of our common stock outstanding on November 1, 2017 and (ii) the number of shares of our common stock issuable upon exercise or conversion of convertible securities that are currently exercisable or convertible or are exercisable or convertible within 60 days of November 1, 2017 beneficially owned by the applicable selling stockholder.


(2)

Contra Costa Capital, LLC is an indirect wholly-owned subsidiary of NextEra Energy, Inc. (NYSE: NEE).

(3)

GKFF Ventures I, LLC is managed by Ken Levit and Robert Thomas. George Kaiser Family Foundation (“GKFF”) is the sole equity owner of GKFF Ventures I, LLC. Messrs. Levit and Thomas and GKFF may be deemed to share voting and investment control over the shares, which are beneficially owned by GKFF Ventures I, LLC.

(4)

RCMF, Ltd is the sole Limited Partner of Reservoir Capital Master Fund, L.P. and Reservoir Overseas Partners, L.P. (“RCOP”) is the sole shareholder of RCMF, Ltd. The General Partner of Reservoir Capital Master Fund, L.P. and RCOP is Reservoir Capital Group, L.L.C. whose Managing Member is RCGM, LLC. Daniel Stern and Craig Huff are the Senior Managing Members of RCGM, LLC. Mr. Huff served on our board of directors from February 2005 to August 2009 and from September 2010 to July 2017.

(5)

The General Partner of Reservoir Capital Partners, L.P. is RCP GP, LLC. Reservoir Capital Partners (Cayman), L.P. is the sole Limited Partner of Reservoir Capital Partners, L.P. and the Sole Member of RCP GP, LLC. The General Partner of Reservoir Capital Partners (Cayman) L.P. is Reservoir Capital Group, L.L.C. whose Managing Member is RCGM, LLC. Daniel Stern and Craig Huff are the Senior Managing Members of RCGM, LLC. Mr. Huff served on our board of directors from February 2005 to August 2009 and from September 2010 to July 2017.

(6)

Consists of 111,218 shares of our common stock held by Mr. Gervis, 72,491 shares of our common stock held by the Robert Gervis 2014 Grantor Retained Annuity Trust, of which Mr. Gervis is a beneficiary and his spouse is trustee, and 27,359 shares of our common stock issuable upon the exercise of options exercisable within 60 days following November 1, 2017. Mr. Gervis currently serves on our Board of Directors.

(7)

Consists of 52,043 shares of our common stock held by Mr. Noetzel and 27,795 shares of our common stock issuable upon the exercise of options exercisable within 60 days following November 1, 2017. Mr. Noetzel currently serves on our Board of Directors.

(8)

Consists of 58,467 shares of our common stock held by Mr. Noglows and 25,048 shares of our common stock issuable upon the exercise of options exercisable within 60 days following November 1, 2017. Mr. Noglows currently serves on our Board of Directors.

(9)

Consists of 48,467 shares of our common stock held by Mr. Reilly and 27,427 shares of our common stock issuable upon the exercise of options exercisable within 60 days following November 1, 2017. Mr. Reilly currently serves on our Board of Directors.

(10)

Consists of 38,467 shares of our common stock held by Mr. Mitchell and 25,027 shares of our common stock issuable upon the exercise of options exercisable within 60 days following November 1, 2017. Mr. Mitchell currently serves on our Board of Directors.

(11)

Consists of 16,935 shares of our common stock held by Mr. Battin. Mr. Battin previously served on our Board of Directors until June 15, 2016.

business.


PLAN OF DISTRIBUTION

The selling stockholders, which as used herein includes donees, pledgees, transferees or other successors-in-interest selling shares of common stock or interests in shares of common stock received after the date ofCertain underwriters may use this prospectus from a selling stockholderand any accompanying prospectus supplement for offers and sales related to market-making transactions in the securities. These underwriters may act as a gift, pledge, partnership distributionprincipal or other transfer, may, from timeagent in these transactions, and the sales will be made at prices related to time, sell, transfer or otherwise dispose of any or all of their shares of common stock or interests in shares of common stock on any stock exchange, market or trading facility on which the shares are traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices.

The selling stockholders may use any one or more of the following methods when disposing of shares or interests therein:

block transactions;

on any national securities exchange or quotation service on which the securities may be listed or quoted at the time of sale;

in the over-the-counter market;

in transactions otherwise than on these exchanges or systems or in the over-the-counter market;

ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;

block trades in which the broker-dealer will attempt to sell the shares as agent but may position and resell a portion of the block as principal to facilitate the transaction;

purchases by a broker-dealer as principal and resale by the broker-dealer for its account;

privately negotiated transactions;

broker-dealers may agree with the selling stockholders to sell a specified number of such shares at a stipulated price per share;

underwritten offerings;

a combination of any such methods of sale; and

any other method permitted pursuant to applicable law.

The selling stockholders may, from time to time, pledge or grant a security interest in some or all of the shares of common stock owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell the shares of common stock, from time to time, under this prospectus, or under an amendment to this prospectus under Rule 424(b)(3) or other applicable provision of the Securities Act amending the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under this prospectus.  The selling stockholders also may transfer the shares of common stock in other circumstances, in which case the transferees, pledgees or other successors in interest will be the selling beneficial owners for purposes of this prospectus.

In connection with the sale of our common stock or interests therein, the selling stockholders may enter into hedging transactions with broker-dealers or other financial institutions, which may in turn engage in short sales of the common stock in the course of hedging the positions they assume.  The selling stockholders may also sell shares of our common stock short and deliver these securities to close out their short positions, or loan or pledge the common stock to broker-dealers that in turn may sell these securities.  The selling stockholders may also enter into option or other transactions with broker-dealers or other financial institutions or the creation of one or more derivative securities which require the delivery to such broker-dealer or other financial institution of shares offered by this prospectus, which shares such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).


The aggregate proceeds to the selling stockholders from the sale of the common stock offered by them will be the purchase price of the common stock less discounts or commissions, if any.  Each of the selling stockholders reserves the right to accept and, together with their agents from time to time, to reject, in whole or in part, any proposed purchase of common stock to be made directly or through agents.  We will not receive any of the proceeds from this offering.

The selling stockholders and anysale. Any underwriters broker-dealers or agents that participateinvolved in the sale of the common stock or interests thereinsecurities may bequalify as “underwriters” within the meaning of Section 2(a)(11) of the Securities Act. Any discounts, commissions, concessions or profit they earn on any resale of the shares may be underwriting discounts and commissions under the Securities Act. Selling stockholders who are “underwriters” within the meaning of Section 2(a)(11) of the Securities Act will be subject to the prospectus delivery requirements of the Securities Act.

To the extent required, the shares of our common stock to be sold, the names of the selling stockholders, the respective purchase prices and public offering prices, the names of any agents, dealer or underwriter, any applicable commissions or discounts with respect to a particular offer will be set forth in an accompanying prospectus supplement or, if appropriate, a post-effective amendment to the registration statement that includes this prospectus.

In order to comply with the securities laws of some states, if applicable, the common stock may be sold in these jurisdictions only through registered or licensed brokers or dealers.  In addition, in some states the common stockunderwriters’ commissions, discounts or concessions may not be sold unless it has been registered or qualified for sale or an exemption from registration or qualification requirements is available and is complied with.

We have advised the selling stockholders that the anti-manipulation rules of Regulation M under the Exchange Act may apply to sales of shares in the market and to the activities of the selling stockholders and their affiliates.  In addition, we will make copies of this prospectus (as it may be supplemented or amended from time to time) available to the selling stockholders for the purpose of satisfying the prospectus delivery requirements of the Securities Act.  The selling stockholders may indemnify any broker-dealer that participates in transactions involving the sale of the shares against certain liabilities, including liabilities arising under the Securities Act.

To the extent required by the Registration Rights Agreement, we have agreed to indemnify certain of the selling stockholders against liabilities, including liabilitiesqualify as underwriters’ compensation under the Securities Act and state securities laws, relating to the registration of certainrules of the shares offered by this prospectus.Financial Industry Regulatory Authority, Inc., or FINRA.

We expectShares of our common stock sold pursuant to keep the registration statement of which this prospectus constitutesis a part effectivewill be authorized for a periodquotation and trading on the NYSE. The applicable prospectus supplement will contain information, where applicable, as to any other listing, if any, on any securities market or other securities exchange of at least eighteen months after the date the registration statement is declared effectivesecurities covered by the SECprospectus supplement. Underwriters may make a market in our common stock, but will not be obligated to do so and may discontinue any market making at any time without notice. We can make no assurance as to the liquidity of or if earlier, until allthe existence, development or maintenance of trading markets for any of the shares coveredsecurities.

In order to facilitate the offering of the securities, certain persons participating in the offering may engage in transactions that stabilize, maintain or otherwise affect the price of the securities. This may include over-allotments or short sales of the securities, which involve the sale by this prospectus have been disposedpersons participating in the offering of pursuantmore securities than we sold to them. In these circumstances, these persons would cover such over-allotments or short positions by making purchases in the open market or by exercising their over-allotment option. In addition, these persons may stabilize or maintain the price of the securities by bidding for or purchasing the applicable security in the open market or by imposing penalty bids, whereby selling concessions allowed to dealers participating in the offering may be reclaimed if the securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. These transactions may be discontinued at any time.

The underwriters, dealers and agents may engage in accordanceother transactions with us, or perform other services for us, in the registration statement.ordinary course of their business.


DESCRIPTION OF CAPITALCOMMON STOCK

We are authorized to issue 125,000,000 shares of common stock, par value $0.00001 per share. On March 9, 2021, we had 28,301,338 shares of common stock outstanding and approximately 27 stockholders of record.

The following statements are qualified in their entirety by referencesummary of certain provisions of our common stock does not purport to the detailed provisions ofbe complete. You should refer to our restated certificate of incorporation and our restated bylaws.bylaws, both of which are included as exhibits to the registration statement of which this prospectus is a part. The summary below is also qualified by provisions of applicable law.

Authorized Capitalization

We currently have authorized capital stock of 125,000,000 shares of our common stock, par value $0.00001 per share, and 5,000,000 shares of preferred stock, par value $0.00001 per share.

As of November 1, 2017, we have 23,637,115 shares of common stock outstanding held of record by 41 stockholders and no shares of preferred stock outstanding.

Common StockGeneral

Holders of our common stock are entitled to one vote for each share held of record on all matters submitted to a vote of the stockholders, and do not have cumulative voting rights. Subject to preferences that may be applicable to any outstanding shares of preferred stock, holders of common stock are entitled to receive ratably such dividends, if any, as may be declared from time to time by our board of directors out of funds legally available for dividend payments. All outstanding shares of common stock areoutstanding as of the date of this prospectus and, upon issuance and sale, all shares of common stock that we may offer pursuant to this prospectus, will be fully paid and nonassessable. The holders of common stock have no preferences or rights of conversion, exchange, pre-emption or other subscription rights. There are no redemption or sinking fund provisions applicable to the common stock. In the event of any liquidation, dissolution or winding-up of our affairs, holders of common stock will be entitled to share ratably in our assets that are remaining after payment or provision for payment of all of our debts and obligations and after liquidation payments to holders of outstanding shares of preferred stock, if any.

Preferred Stock

If we issue preferred stock in the future, such preferred stock would have priority over common stock with respect to dividends and other distributions, including the distribution of assets upon liquidation.  Our board of directors has the authority, without further stockholder authorization, to issue from time to time up to 5,000,000 shares of preferred stock in one or more series and to fix the terms, limitations, voting The rights, relative rights and preferences and variationsprivileges of each series. Although we have no present plans to issue any shares of preferred stock, the issuance of shares of preferred stock, or the issuance of rights to purchase such shares, could decrease the amount of earnings and assets available for distribution to the holders of common stock couldare subject to and may be adversely affectaffected by the rights and powers, including voting rights of the common stock and could have the effectholders of delaying, deterring or preventing a change of control of us or an unsolicited acquisition proposal.

Warrants

As of November 1, 2017, we had outstanding warrants to purchase 120 shares of our common stock at an exercise priceany series of $8.25 per share, which expire on December 29, 2017.then outstanding preferred stock.

Registration Rights

Pursuant to our registration rights agreement to which certain of our principal stockholders, directors and executive officers are parties, including GKFF Ventures I, LLC; Reservoir Capital Partners, L.P. and affiliated funds; certain entities affiliated with Fidelity Investments; Donald R. Young, our President, Chief Executive Officer and one of our directors; and John F. Fairbanks, our Vice President, Chief Financial Officer and Treasurer, are entitled to registration rights with respect to the shares of common stock held by them. These shares include substantially all of the shares held by GKFF Ventures I, LLC; Reservoir Capital Partners, L.P. and affiliated funds; certain entities affiliated with Fidelity Investments; and certain shares held by Donald R. Young, our President, Chief Executive Officer and one of our directors; and John F. Fairbanks, our Vice President, Chief Financial Officer and Treasurer. We are generally required to pay all expenses incurred in connection with registrations effected in connection with the following rights, excluding underwriting discounts. All registration rights described below will terminate at the earlier of (1) the seventh anniversary of the completion of our initial public offering, or June 18, 2021, (2) such shares have been registered under the Securities Act, such registration statement has been declared


effective and the shares have been disposed of pursuant to such effective registration statement, and (3) with respect to any holder of registrable shares that (together with its affiliates) holds less than 1% of our common stock (on an as-if-converted to common stock basis), when such holder can sell all of such shares without limitation under Rule 144 promulgated under the Securities Act during any 90 day period. The registration statement of which this prospectus forms a part is a shelf registration statement that we are required to file under the registration rights agreement pursuant to the “ – Form S-3 rights” section below.

Demand rights. Subject to specified limitations, the holders representing at least a majority of these registrable shares then outstanding may require that we register all or a portion of these securities for sale under the Securities Act, which we refer to as a demand registration, if the anticipated aggregate offering price of such securities is at least $10,000,000. We may be required to effect up to two such registrations at our expense and up to two such registrations at the holders’ expense. Stockholders with these registration rights who are not part of an initial registration demand are entitled to notice and are entitled to include their shares of common stock in the registration. Under certain circumstances, the underwriters, if any, may limit the number of shares included in any such registration.

Piggyback rights. If we propose to register any of our equity securities under the Securities Act, other than in connection with (i) a registration relating solely to our employee benefit plans, or (ii) a registration relating solely to a business combination or merger involving us, the holders of these registrable shares are entitled to notice of such registration and are entitled to include their shares of common stock in the registration. Under certain circumstances, the underwriters, if any, may limit the number of shares included in any such registration.

Form S-3 rights. If we become eligible to file registration statements on Form S-3, subject to specified limitations, the holders of these registrable shares may require us to register all or a portion of their registrable shares on Form S-3, if the anticipated aggregate offering price of such securities is at least $2,000,000. Such requests for registration will not be considered a demand registration pursuant to the “—Demand rights” section above. We are not required to (i) effect more than two such registrations in any 12-month period or (ii) keep effective at any one time more than one registration statement on Form S-3 with respect to the registrable shares. Stockholders with these registration rights who are not part of an initial registration demand are entitled to notice and are entitled to include their shares of common stock in the registration. Under certain circumstances, the underwriters, if any, may limit the number of shares included in any such registration.

Anti-Takeover EffectsTransfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A., P.O. Box 30170, College Station, Texas 77842.

Stock Exchange Listing

Our common stock is listed for trading on New York Stock Exchange under the symbol “ASPN.”

DESCRIPTION OF PREFERRED STOCK

We are authorized to issue 5,000,000 shares of blank check preferred stock, par value $0.00001 per share. As of the date of this prospectus, no shares of our preferred stock were outstanding or designated. The following summary of certain provisions of our preferred stock does not purport to be complete. You should refer to our restated certificate of incorporation and our restated bylaws, both of which are included as exhibits to the registration statement of which this prospectus is a part. The summary below is also qualified by provisions of applicable law.

General

Our board of directors has the authority, without further stockholder authorization, to issue from time to time up to 5,000,000 shares of preferred stock in one or more series and to fix the terms, limitations, voting rights, relative rights and preferences and variations of each series. If we issue preferred stock in the future, such preferred stock would have priority over common stock with respect to dividends and other distributions, including the distribution of assets upon liquidation. The issuance of shares of preferred stock, or the issuance of rights to purchase such shares, could decrease the amount of earnings and assets available for distribution to the holders of common stock, could adversely affect the rights and powers, including voting rights, of the common stock and could have the effect of delaying, deterring or preventing a change of control of us or an unsolicited acquisition proposal.

If we offer a specific series of preferred stock under this prospectus, we will describe the terms of the preferred stock in the prospectus supplement for such offering and will file a copy of the certificate establishing the terms of the preferred stock with the SEC. To the extent required, this description will include:

the title and stated value;

the number of shares offered, the liquidation preference, if any, per share and the purchase price;

the dividend rate(s), period(s) and/or payment date(s), or method(s) of calculation for such dividends;

whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;

the procedures for any auction and remarketing, if any;

the provisions for a sinking fund, if any;

the provisions for redemption, if applicable;

any listing of the preferred stock on any securities exchange or market;

whether the preferred stock will be convertible into our common stock, and, if applicable, the conversion price (or how it will be calculated) and conversion period;

whether the preferred stock will be exchangeable into debt securities, and, if applicable, the exchange price (or how it will be calculated) and exchange period;

voting rights, if any, of the preferred stock;

a discussion of any material and/or special U.S. federal income tax considerations applicable to the preferred stock;

the relative ranking and preferences of the preferred stock as to dividend rights and rights upon liquidation, dissolution or winding up of the affairs of the Company; and

any material limitations on issuance of any class or series of preferred stock ranking pari passu with or senior to the series of preferred stock as to dividend rights and rights upon liquidation, dissolution or winding up of the Company.

Transfer Agent and Registrar

The transfer agent and registrar for our preferred stock will be set forth in the applicable prospectus supplement.

DESCRIPTION OF DEBT SECURITIES

The following description, together with the additional information we include in any applicable prospectus supplements, summarizes the material terms and provisions of the debt securities that we may offer under this prospectus. While the terms we have summarized below will apply generally to any future debt securities we may offer pursuant to this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. If we so indicate in a prospectus supplement, the terms of any debt securities offered under such prospectus supplement may differ from the terms we describe below, and to the extent the terms set forth in a prospectus supplement differ from the terms described below, the terms set forth in the prospectus supplement shall control.

We may sell from time to time, in one or more offerings under this prospectus, debt securities, which may be senior or subordinated. We will issue any such senior debt securities under a senior indenture that we will enter into with a trustee to be named in the senior indenture. We will issue any such subordinated debt securities under a subordinated indenture, which we will enter into with a trustee to be named in the subordinated indenture. We have filed forms of these documents as exhibits to the registration statement, of which this prospectus is a part. We use the term “indentures” to refer to either the senior indenture or the subordinated indenture, as applicable. The indentures will be qualified under the Trust Indenture Act of 1939, as in effect on the date of the indenture. We use the term “debenture trustee” to refer to either the trustee under the senior indenture or the trustee under the subordinated indenture, as applicable.

The following summaries of material provisions of the senior debt securities, the subordinated debt securities and the indentures are subject to, and qualified in their entirety by reference to, all the provisions of the indenture applicable to a particular series of debt securities.

General

Each indenture provides that debt securities may be issued from time to time in one or more series and may be denominated and payable in foreign currencies or units based on or relating to foreign currencies. Neither indenture limits the amount of debt securities that may be issued thereunder. Each indenture provides that the specific terms of any series of debt securities shall be set forth in, or determined pursuant to, an authorizing resolution and/or a supplemental indenture, if any, relating to such series.

We will describe in each prospectus supplement the following terms relating to a series of debt securities:

the title or designation;

the aggregate principal amount and any limit on the amount that may be issued;

the currency or units based on or relating to currencies in which debt securities of such series are denominated and the currency or units in which principal or interest or both will or may be payable;

whether we will issue the series of debt securities in global form, the terms of any global securities and who the depositary will be;

the maturity date and the date or dates on which principal will be payable;

the interest rate, which may be fixed or variable, or the method for determining the rate and the date interest will begin to accrue, the date or dates interest will be payable and the record dates for interest payment dates or the method for determining such dates;

whether or not the debt securities will be secured or unsecured, and the terms of any secured debt;

the terms of the subordination of any series of subordinated debt;

the place or places where payments will be payable;

our right, if any, to defer payment of interest and the maximum length of any such deferral period;

the date, if any, after which, and the price at which, we may, at our option, redeem the series of debt securities pursuant to any optional redemption provisions;

the date, if any, on which, and the price at which we are obligated, pursuant to any mandatory sinking fund provisions or otherwise, to redeem, or at the holder’s option to purchase, the series of debt securities;

whether the indenture will restrict our ability to pay dividends, or will require us to maintain any asset ratios or reserves;

whether we will be restricted from incurring any additional indebtedness;

a discussion of any material or special U.S. federal income tax considerations applicable to a series of debt securities;

the denominations in which we will issue the series of debt securities, if other than denominations of $1,000 and any integral multiple thereof; and

any other specific terms, preferences, rights or limitations of, or restrictions on, the debt securities.

We may issue debt securities that provide for an amount less than their stated principal amount to be due and payable upon declaration of acceleration of their maturity pursuant to the terms of the indenture. We will provide you with information on the federal income tax considerations and other special considerations applicable to any of these debt securities in the applicable prospectus supplement.

Conversion or Exchange Rights

We will set forth in the prospectus supplement the terms, if any, on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale; No Protection in Event of a Change of Control or Highly Leveraged Transaction

The indentures do not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of all or substantially all of our assets. However, any successor to or acquirer of such assets must assume all of our obligations under the indentures or the debt securities, as appropriate.

Unless we state otherwise in the applicable prospectus supplement, the debt securities will not contain any provisions that may afford holders of the debt securities protection in the event we have a change of control or in the event of a highly leveraged transaction (whether or not such transaction results in a change of control), which could adversely affect holders of debt securities.

Events of Default Under the Indenture

The following are events of default under the indentures with respect to any series of debt securities that we may issue:

if we fail to pay interest when due and our failure continues for 90 days and the time for payment has not been extended or deferred;

if we fail to pay the principal, or premium, if any, when due and the time for payment has not been extended or delayed;

if we fail to observe or perform any other covenant set forth in the debt securities of such series or the applicable indentures, other than a covenant specifically relating to and for the benefit of holders of another series of debt securities, and our failure continues for 90 days after we receive written notice from the debenture trustee or holders of not less than a majority in aggregate principal amount of the outstanding debt securities of the applicable series; and

if specified events of bankruptcy, insolvency or reorganization occur as to us.

No event of default with respect to a particular series of debt securities (except as to certain events of bankruptcy, insolvency or reorganization) necessarily constitutes an event of default with respect to any other series of debt securities. The occurrence of an event of default may constitute an event of default under any bank credit agreements we may have in existence from time to time. In addition, the occurrence of certain events of default or an acceleration under the indenture may constitute an event of default under certain of our other indebtedness outstanding from time to time.

If an event of default with respect to debt securities of any series at the time outstanding occurs and is continuing, then the trustee or the holders of not less than a majority in principal amount of the outstanding debt securities of that series may, by a notice in writing to us (and to the debenture trustee if given by the holders), declare to be due and payable immediately the principal (or, if the debt securities of that series are discount securities, that portion of the principal amount as may be specified in the terms of that series) of and premium and accrued and unpaid interest, if any, on all debt securities of that series. Before a judgment or decree for payment of the money due has been obtained with respect to debt securities of any series, the holders of a majority in principal amount of the outstanding debt securities of that series (or, at a meeting of holders of such series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) may rescind and annul the acceleration if all events of default, other than the non-payment of accelerated principal, premium, if any, and interest, if any, with respect to debt securities of that series, have been cured or waived as provided in the applicable indenture (including payments or deposits in respect of principal, premium or interest that had become due other than as a result of such acceleration). We refer you to the prospectus supplement relating to any series of debt securities that are discount securities for the particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of an event of default.

Subject to the terms of the indentures, if an event of default under an indenture shall occur and be continuing, the debenture trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the debenture trustee reasonable indemnity. The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the debenture trustee, or exercising any trust or power conferred on the debenture trustee, with respect to the debt securities of that series, provided that:

the direction so given by the holder is not in conflict with any law or the applicable indenture; and

subject to its duties under the Trust Indenture Act, the debenture trustee need not take any action that might involve it in personal liability or might be unduly prejudicial to the holders not involved in the proceeding.

A holder of the debt securities of any series will only have the right to institute a proceeding under the indentures or to appoint a receiver or trustee, or to seek other remedies if:

the holder previously has given written notice to the debenture trustee of a continuing event of default with respect to that series;

the holders of at least a majority in aggregate principal amount of the outstanding debt securities of that series have made written request, and such holders have offered reasonable indemnity to the debenture trustee to institute the proceeding as trustee; and

the debenture trustee does not institute the proceeding, and does not receive from the holders of a majority in aggregate principal amount of the outstanding debt securities of that series (or at a meeting of holders of such series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) other conflicting directions within 60 days after the notice, request and offer.

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the applicable debenture trustee regarding our compliance with specified covenants in the applicable indenture.

Modification of Indenture; Waiver

The debenture trustee and we may change the applicable indenture without the consent of any holders with respect to specific matters, including:

to fix any ambiguity, defect or inconsistency in the indenture; and

to change anything that does not materially adversely affect the interests of any holder of debt securities of any series issued pursuant to such indenture.

In addition, under the indentures, the rights of holders of a series of debt securities may be changed by us and the debenture trustee with the written consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities of each series (or, at a meeting of holders of such series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) that is affected. However, the debenture trustee and we may make the following changes only with the consent of each holder of any outstanding debt securities affected:

extending the fixed maturity of the series of debt securities;

reducing the principal amount, reducing the rate of or extending the time of payment of interest, or any premium payable upon the redemption of any debt securities;

reducing the principal amount of discount securities payable upon acceleration of maturity;

making the principal of or premium or interest on any debt security payable in currency other than that stated in the debt security; or

reducing the percentage of debt securities, the holders of which are required to consent to any amendment or waiver.

Except for certain specified provisions, the holders of at least a majority in principal amount of the outstanding debt securities of any series (or, at a meeting of holders of such series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) may on behalf of the holders of all debt securities of that series waive our compliance with provisions of the indenture. The holders of a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all the debt securities of such series waive any past default under the indenture with respect to that series and its consequences, except a default in the payment of the principal of, premium or any interest on any debt security of that series or in respect of a covenant or provision, which cannot be modified or amended without the consent of the holder of each outstanding debt security of the series affected; provided, however, that the holders of a majority in principal amount of the outstanding debt securities of any series may rescind an acceleration and its consequences, including any related payment default that resulted from the acceleration.

Discharge

Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for obligations to:

the transfer or exchange of debt securities of the series;

replace stolen, lost or mutilated debt securities of the series;

maintain paying agencies;

hold monies for payment in trust;

compensate and indemnify the trustee; and

appoint any successor trustee.

In order to exercise our rights to be discharged with respect to a series, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, the premium, if any, and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange, and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we otherwise specify in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indentures provide that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company or another depositary named by us and identified in a prospectus supplement with respect to that series.

At the option of the holder, subject to the terms of the indentures and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indentures and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange or in the applicable indenture, we will make no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

issue, register the transfer of, or exchange any debt securities of that series during a period beginning at the opening of business 15 days before the day of mailing of a notice of redemption of any debt securities that may be selected for redemption and ending at the close of business on the day of the mailing; or

register the transfer of or exchange any debt securities so selected for redemption, in whole or in part, except the unredeemed portion of any debt securities we are redeeming in part.

Information Concerning the Debenture Trustee

The debenture trustee, other than during the occurrence and continuance of an event of default under the applicable indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the debenture trustee under such indenture must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the debenture trustee is under no obligation to exercise any of the powers given it by the indentures at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, will we make interest payments by check which we will mail to the holder. Unless we otherwise indicate in a prospectus supplement, we will designate the corporate trust office of the debenture trustee in the City of New York as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the debenture trustee for the payment of the principal of or any premium or interest on any debt securities which remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the security thereafter may look only to us for payment thereof.

Governing Law

The indentures and the debt securities will be governed by and construed in accordance with the laws of the State of Delaware, Lawexcept to the extent that the Trust Indenture Act is applicable.

Subordination of Subordinated Debt Securities

Our obligations pursuant to any subordinated debt securities will be unsecured and Our Restated Certificatewill be subordinate and junior in priority of Incorporationpayment to certain of our other indebtedness to the extent described in a prospectus supplement. The subordinated indenture does not limit the amount of senior indebtedness we may incur. It also does not limit us from issuing any other secured or unsecured debt.

DESCRIPTION OF WARRANTS

General

We may issue warrants to purchase shares of our common stock, preferred stock and/or debt securities in one or more series together with other securities or separately, as described in the applicable prospectus supplement. Below is a description of certain general terms and Restated By-Lawsprovisions of the warrants that we may offer. Particular terms of the warrants will be described in the warrant agreements and the prospectus supplement relating to the warrants.

The applicable prospectus supplement will contain, where applicable, the following terms of and other information relating to the warrants:

the specific designation and aggregate number of, and the price at which we will issue, the warrants;

the currency or currency units in which the offering price, if any, and the exercise price are payable;

the designation, amount and terms of the securities purchasable upon exercise of the warrants;

if applicable, the exercise price for shares of our common stock and the number of shares of common stock to be received upon exercise of the warrants;

if applicable, the exercise price for shares of our preferred stock, the number of shares of preferred stock to be received upon exercise, and a description of that series of our preferred stock;

if applicable, the exercise price for our debt securities, the amount of debt securities to be received upon exercise, and a description of that series of debt securities;

the date on which the right to exercise the warrants will begin and the date on which that right will expire or, if you may not continuously exercise the warrants throughout that period, the specific date or dates on which you may exercise the warrants;

whether the warrants will be issued in fully registered form or bearer form, in definitive or global form or in any combination of these forms, although, in any case, the form of a warrant included in a unit will correspond to the form of the unit and of any security included in that unit;

any applicable material U.S. federal income tax consequences;

the identity of the warrant agent for the warrants and of any other depositaries, execution or paying agents, transfer agents, registrars or other agents;

the proposed listing, if any, of the warrants or any securities purchasable upon exercise of the warrants on any securities exchange;

if applicable, the date from and after which the warrants and the common stock, preferred stock and/or debt securities will be separately transferable;

if applicable, the minimum or maximum amount of the warrants that may be exercised at any one time;

information with respect to book-entry procedures, if any;

the anti-dilution provisions of the warrants, if any;

any redemption or call provisions;

whether the warrants may be sold separately or with other securities as parts of units; and

any additional terms of the warrants, including terms, procedures and limitations relating to the exchange and exercise of the warrants.

Exercise of Warrants

Each warrant will entitle the holder to purchase for cash such shares of our common stock and/or our preferred stock and/or our debt securities at such exercise price as shall be in each case be set forth in, or be determinable

as set forth in, the prospectus supplement relating to the warrants offered thereby. Warrants may be exercised at any time up to the close of business on the expiration date set forth in the prospectus supplement relating to the warrants offered thereby. After the close of business on the expiration date, unexercised warrants will become void.

The warrants may be exercised as set forth in the prospectus supplement relating to the warrants offered. Upon receipt of payment and the warrant certificate properly completed and duly executed at the corporate trust office of the warrant agent or any other office indicated in the prospectus supplement, we will, as soon as practicable, forward the shares of our common stock and/or our preferred stock and/or our debt securities purchasable upon such exercise. If less than all of the warrants represented by such warrant certificate are exercised, a new warrant certificate will be issued for the remaining warrants.

Warrant Agent

The name and address of the warrant agent for any warrants we offer will be set forth in the applicable prospectus supplement.

Enforceability of Rights by Holders of Warrants

If we appoint a warrant agent, any warrant agent will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

Outstanding Warrants

As of March 11, 2021, we had no warrants outstanding.

DESCRIPTION OF RIGHTS

General

We may issue rights to our stockholders to purchase shares of our common stock, preferred stock or the other securities described in this prospectus. We may offer rights separately or together with one or more additional rights, debt securities, preferred stock, common stock or warrants, or any combination of those securities in the form of units, as described in the applicable prospectus supplement. Each series of rights will be issued under a separate rights agreement to be entered into between us and a bank or trust company, as rights agent. The rights agent will act solely as our agent in connection with the certificates relating to the rights of the series of certificates and will not assume any obligation or relationship of agency or trust for or with any holders of rights certificates or beneficial owners of rights. The following description sets forth certain general terms and provisions of the rights to which any prospectus supplement may relate. The particular terms of the rights to which any prospectus supplement may relate and the extent, if any, to which the general provisions may apply to the rights so offered will be described in the applicable prospectus supplement. To the extent that any particular terms of the rights, rights agreement or rights certificates described in a prospectus supplement differ from any of the terms described below, then the terms described below will be deemed to have been superseded by that prospectus supplement. We encourage you to read the applicable rights agreement and rights certificate for additional information before you decide whether to purchase any of our rights.

We will provide in a prospectus supplement the following terms of the rights being issued:

the date of determining the stockholders entitled to the rights distribution;

the aggregate number of shares of common stock, preferred stock or other securities purchasable upon exercise of the rights;

the exercise price;

the aggregate number of rights issued;

whether the rights are transferrable and the date, if any, on and after which the rights may be separately transferred;

the date on which the right to exercise the rights will commence, and the date on which the right to exercise the rights will expire;

the method by which holders of rights will be entitled to exercise;

the conditions to the completion of the offering, if any;

the withdrawal, termination and cancellation provisions, if any;

whether there are any backstop or standby purchaser or purchasers and the terms of their commitment, if any;

whether securityholders are entitled to oversubscription rights, if any;

any applicable material U.S. federal income tax considerations; and

any other terms of the rights, including terms, procedures and limitations relating to the distribution, exchange and exercise of the rights, as applicable.

Each right will entitle the holder of rights to purchase for cash the principal amount of shares of common stock, preferred stock or other securities at the exercise price provided in the applicable prospectus supplement. Rights may be exercised at any time up to the close of business on the expiration date for the rights provided in the applicable prospectus supplement.

Holders may exercise rights as described in the applicable prospectus supplement. Upon receipt of payment and the rights certificate properly completed and duly executed at the corporate trust office of the rights agent or any

other office indicated in the prospectus supplement, we will, as soon as practicable, forward the shares of common stock, preferred stock or other securities, as applicable, purchasable upon exercise of the rights. If less than all of the rights issued in any rights offering are exercised, we may offer any unsubscribed securities directly to persons other than stockholders, to or through agents, underwriters or dealers or through a combination of such methods, including pursuant to standby arrangements, as described in the applicable prospectus supplement.

Rights Agent

The name and address of the rights agent for any rights we offer will be set forth in the applicable prospectus supplement.

DESCRIPTION OF UNITS

The following description, together with the additional information that we include in any applicable prospectus supplements summarizes the material terms and provisions of the units that we may offer under this prospectus. While the terms we have summarized below will apply generally to any units that we may offer under this prospectus, we will describe the particular terms of any series of units in more detail in the applicable prospectus supplement. The terms of any units offered under a prospectus supplement may differ from the terms described below.

We will incorporate by reference from reports that we file with the SEC, the form of unit agreement that describes the terms of the series of units we are offering, and any supplemental agreements, before the issuance of the related series of units. The following summaries of material terms and provisions of the units are subject to, and qualified in their entirety by reference to, all the provisions of the unit agreement and any supplemental agreements applicable to a particular series of units. We urge you to read the applicable prospectus supplements related to the particular series of units that we may offer under this prospectus, as well as any related free writing prospectuses and the complete unit agreement and any supplemental agreements that contain the terms of the units.

General

We may issue units consisting of common stock, preferred stock, one or more debt securities, warrants or rights for the purchase of common stock, preferred stock and/or debt securities in one or more series, in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each security included in the unit. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date.

We will describe in the applicable prospectus supplement the terms of the series of units being offered, including:

the designation and terms of the units and of the securities comprising the units, including whether and under what circumstances those securities may be held or transferred separately;

any provisions of the governing unit agreement that differ from those described below; and

any provisions for the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units.

The provisions described in this section, as well as those set forth in any prospectus supplement or as described under “Description of Common Stock,” “Description of Preferred Stock,” “Description of Debt Securities,” “Description of Warrants,” and “Description of Rights” will apply to each unit, as applicable, and to any common stock, preferred stock, debt security, warrant, or right included in each unit, as applicable.

Unit Agent

The name and address of the unit agent for any units we offer will be set forth in the applicable prospectus supplement.

Issuance in Series

We may issue units in such amounts and in such numerous distinct series as we determine.

Enforceability of Rights by Holders of Units

Each unit agent will act solely as our agent under the applicable unit agreement and will not assume any obligation or relationship of agency or trust with any holder of any unit. A single bank or trust company may act

as unit agent for more than one series of units. A unit agent will have no duty or responsibility in case of any default by us under the applicable unit agreement or unit, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a unit may, without the consent of the related unit agent or the holder of any other unit, enforce by appropriate legal action its rights as holder under any security included in the unit.

CERTAIN PROVISIONS OF DELAWARE LAW AND OF THE COMPANY’S RESTATED CERTIFICATE OF INCORPORATION AND RESTATED BYLAWS

Anti-Takeover Provisions

The provisions of Delaware law, our restated certificate of incorporation and our restated by-lawsbylaws discussed below could discourage or make it more difficult to accomplish a proxy contest or other change in our management or the acquisition of control by a holder of a substantial amount of our voting stock. It is possible that these provisions could make it more difficult to accomplish, or could deter, transactions that stockholders may otherwise consider to be in their best interests or in our best interests. These provisions are intended to enhance the likelihood of continuity and stability in the composition of our board of directors and in the policies formulated by the board of directors and to discourage certain types of transactions that may involve an actual or threatened change of our control. These provisions are designed to reduce our vulnerability to an unsolicited acquisition proposal and to discourage certain tactics that may be used in proxy fights. Such provisions also may have the effect of preventing changes in our management.

Delaware Statutory Business Combinations Provision

We are subject to the anti-takeover provisions of Section 203 of the Delaware General Corporation Law. Section 203This statute regulating corporate takeovers prohibits a publicly-held Delaware corporation from engaging in a “business combination”any business combination with an “interested stockholder”any interested stockholder for a period of three years afterfollowing the date that the stockholder became an interested stockholder, unless:

prior to the date of the transaction, the board of directors of the corporation approved either the business combination or the transaction which resulted in which the person becamestockholder becoming an interested stockholder;

upon completion of the transaction that resulted in the interested stockholder becoming an interested stockholder, unlessthe interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the number of shares outstanding (a) shares owned by persons who are directors and also officers, and (b) shares owned by employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or

on or subsequent to the date of the transaction, the business combination is approved by the board of directors and authorized at an annual or special meeting of stockholders, and not by written consent, by the transaction inaffirmative vote of at least 66 2/3% of the outstanding voting stock which is not owned by the person became an interested stockholder was, approved instockholder.

Generally, a prescribed manner or another prescribed exception applies. For purposes of Section 203, a “business combination” is defined broadly to includebusiness combination includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. An interested stockholder and, subject to certain exceptions, an “interested stockholder” is aany person who, together with his or hersuch person’s affiliates and associates (i) owns 15% or within three years prior, did own,more of a corporation’s voting securities or (ii) is an affiliate or associate of a corporation and was the owner of 15% or more of the corporation’s voting stock.securities at any time within the three year period immediately preceding a business combination of the corporation governed by Section 203. We expect the existence of this provision to have an anti-takeover effect with respect to transactions our board of directors does not approve in advance. We also anticipate that Section 203 may discourage takeover attempts that might result in a premium over the market price for the shares of Common Stock held by our stockholders.


Classified Board of Directors; Removal of Directors for Cause

Our restated certificate of incorporation and restated by-lawsbylaws provide that our board of directors arewill be divided into three classes, with the term of office of the first class to expire at the first annual meeting of stockholders following the initial classification of directors, the term of office of the second class to expire at the second annual meeting of stockholders following the initial classification of directors and the term of office of the third

class to expire at the third annual meeting of stockholders following the initial classification of directors. At each annual meeting of stockholders, directors elected to succeed those directors whose terms expire will be elected for a three-year term of office. All directors elected to our classified board of directors will serve until the election and qualification of their respective successors or their earlier resignation or removal. The board of directors is authorized to create new directorships and to fill such positions so created and is permitted to specify the class to which any such new position is assigned. The person filling such position would serve for the term applicable to that class. The board of directors, or its remaining members, even if less than a quorum, is also empowered to fill vacancies on the board of directors occurring for any reason for the remainder of the term of the class of directors in which the vacancy occurred. Members of the board of directors may only be removed for cause and only by the affirmative vote of 75% of our outstanding voting stock. These provisions are likely to increase the time required for stockholders to change the composition of the board of directors. For example, at least two annual meetings will be necessary for stockholders to effect a change in a majority of the members of the board of directors.

Advance Notice Provisions for Stockholder Proposals and Stockholder Nominations of Directors

Our restated by-lawsbylaws provide that, for nominations to the board of directors or for other business to be properly brought by a stockholder before a meeting of stockholders, the stockholder must first have given timely notice of the proposal in writing to our Secretary. For an annual meeting, a stockholder’s notice generally must be delivered not less than 90 days nor more than 120 days prior to the anniversary of the previous year’s annual meeting. For a special meeting, the notice must generally be delivered not earlier than the 90th day prior to the meeting and not later than the later of (1) the 60th day prior to the meeting or (2) the 10th day following the day on which public announcement of the meeting is first made. Detailed requirements as to the form of the notice and information required in the notice are specified in the restated by-laws.bylaws. If it is determined that business was not properly brought before a meeting in accordance with our bylaw provisions, such business will not be conducted at the meeting.

Special Meetings of Stockholders

Special meetings of the stockholders may be called only by our board of directors pursuant to a resolution adopted by a majority of the total number of directors.

No Stockholder Action by Written Consent

AnyOur restated certificate of incorporation and restated bylaws do not permit our stockholders to act by written consent. As a result, any action to be effected by our stockholders must be effected at a duly called annual or special meeting of the stockholders.

Super Majority Stockholder Vote Required for Certain Actions

The Delaware General Corporation Law provides generally that the affirmative vote of a majority of the shares entitled to vote on any matter is required to amend a corporation’s certificate of incorporation or by-laws,bylaws, unless the corporation’s certificate of incorporation or by-laws,bylaws, as the case may be, requires a greater percentage. Our restated certificate of incorporation requires the affirmative vote of the holders of at least 75% of our outstanding voting stock to amend or repeal any of the provisions discussed in this section of this prospectus entitled “— Anti-Takeover Effects of Delaware Law and Our Restated Certificate of Incorporation and Restated By-Laws”Provisions” or to reduce the number of authorized shares of common stock or preferred stock. This 75% stockholder vote would be in addition to any separate class vote that might in the future be required pursuant to the terms of any preferred stock that might then be outstanding. In addition, a 75% vote is also required for any amendment to, or repeal of, our restated by-lawsbylaws by the stockholders. Our restated by-lawsbylaws may be amended or repealed by a simple majority vote of the board of directors.


Exclusive Forum

Our restated certificate of incorporation provides that, subject to limited exceptions, a state or federal court located within the State of Delaware will be the sole and exclusive forum for (1) any derivative action or proceeding brought on our behalf, (2) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers or other employees to us or our stockholders, (3) any action asserting a claim against us arising pursuant to any provision of the Delaware General Corporation Law, our certificate of incorporation or our by-laws,bylaws, or (4) any other action asserting a claim against us that is governed by the internal affairs doctrine. Any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock shall be deemed to have notice of and to have consented to the provisions of our restated certificate of incorporation described above. Although we believe these provisions benefit us by providing increased consistency in the application of Delaware law for the specified types of actions and proceedings, the provisions may have the effect of discouraging lawsuits against our directors and officers. The enforceability of similar choice of forum provisions in other companies’ certificates of incorporation has been challenged in legal proceedings, and it is possible that, in connection with one or more actions or proceedings described above, a court could find the choice of forum provisions contained in our restated certificate of incorporation to be inapplicable or unenforceable.

Limitation of Directors’ and Officers’ Liability and Indemnification

The Delaware General Corporation Law authorizes corporations to limit or eliminate, subject to specified conditions, the personal liability of directors to corporations and their stockholders for monetary damages for breach of their fiduciary duties. Our existing restated certificate of incorporation, as amended, limits the liability of our directors to the fullest extent permitted by Delaware law.

We have obtained director and officer liability insurance to cover liabilities our directors and officers may incur in connection with their services to us. Our restated certificate of incorporation and restated by-laws alsobylaws provide that we will indemnify and advance expenseseach person who was or is made a party or is threatened to be made a party to or is otherwise involved (including, without limitation, as a witness) in any of our directors and officers who,action, suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that he or she is or was one of our directors or officers or directors, is involved in a legal proceeding of any nature. We will repay certain expenses incurred byor was serving at our request as a director, officer or trustee of another corporation, or of a partnership, joint venture, trust or other enterprise, including service with respect to an employee benefit plan, whether the basis of such proceeding is alleged action in an official capacity as a director, officer or trustee or in connection with any civil, criminal, administrativeother capacity while serving as a director, officer or investigative action or proceeding, including actionstrustee, shall be indemnified and held harmless by us or in our name. Such indemnifiable expenses include, to the maximumfullest extent permittedauthorized by law, attorney’sthe Delaware General Corporation Law against all expense, liability and loss (including attorneys’ fees, judgments, fines, ERISA excise taxes or penalties and amounts paid in settlement) reasonably incurred or suffered by such.

Section 145 of the Delaware General Corporation Law permits a corporation to indemnify any director or officer of the corporation against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement amountsactually and other expenses reasonably incurred in connection with legal proceedings. Aany action, suit or proceeding brought by reason of the fact that such person is or was a director or officer will not receive indemnificationof the corporation, if he or she is found not to havesuch person acted in good faith and in a manner that he or she reasonably believed to be in, or not opposed to, the best interests of the corporation, and, with respect to any criminal action or proceeding, if he or she had no reasonable cause to believe his or her conduct was unlawful. In a derivative action (i.e., one brought by or on behalf of the corporation), indemnification may be provided only for expenses actually and reasonably incurred by any director or officer in connection with the defense or settlement of such an action or suit if such person acted in good faith and in a manner that he or she reasonably believed to be in, or not opposed to, the best interests of the corporation, except that no indemnification shall be provided if such person shall have been adjudged to be liable to the corporation, unless and only to the extent that the Delaware Chancery Court or the court in which the action or suit was brought shall determine that such person is fairly and reasonably entitled to indemnity for such expenses despite such adjudication of liability.

Pursuant to Section 102(b)(7) of the Delaware General Corporation Law, Article VI of our best interest.restated certificate of incorporation eliminates the liability of a director to us or our stockholders for monetary damages for such a breach of fiduciary duty as a director, except for liabilities arising:

from any breach of the director’s duty of loyalty to us or our stockholders;

from acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law;

under Section 174 of the Delaware General Corporation Law; and

from any transaction from which the director derived an improper personal benefit.

We have entered into indemnification agreements with eachour non-employee directors and with certain officers, in addition to the indemnification provided for in our restated certificate of incorporation and restated bylaws, and intend to enter into indemnification agreements with any new directors and executive officers in the future. We have purchased and intend to maintain insurance on behalf of any person who is or was a director or officer against any loss arising from any claim asserted against him or her and incurred by him or her in any such capacity, subject to certain exclusions.

The foregoing discussion of our non-employee directorsrestated certificate of incorporation, restated bylaws, indemnification agreements and certain officers. TheseDelaware law is not intended to be exhaustive and is qualified in its entirety by such restated certificate of incorporation, restated bylaws, indemnification agreements provide that we will, among other things, indemnify and advance expensesor law.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to our directors, officers and officers for certain expenses, including attorneys’ fees, judgments, fines and settlement amounts incurred by any such person in any investigation, actioncontrolling persons pursuant to the foregoing provisions, or proceeding, including any action by us arising out of such person’s services as our director or officer, or any other company or enterprise to which the person provides services at our request. We believe that these provisions and agreements are necessary to attract and retain qualified persons as directors and officers.

Such limitation of liability and indemnification does not affect the availability of equitable remedies. In addition,otherwise, we have been advised that in the opinion of the SEC such indemnification for liabilities arising under the Securities Act is against public policy as expressed in the Securities Act and is, therefore, unenforceable.

There is no pending litigation or proceeding involving any of our directors, officers, employees or agents in which indemnification will be required or permitted. We are not aware of any threatened litigation or proceeding that may result in a claim for such indemnification.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A., with offices at 250 Royall Street, Canton, Massachusetts 02021.


LEGAL MATTERS

The validity of the shares of common stock being offered by this prospectus has been passed upon for us by Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., Boston, Massachusetts.Massachusetts, will pass upon the validity of the issuance of the securities to be offered by this prospectus.

EXPERTS

The consolidated financial statements and schedule of Aspen Aerogels, Inc. as of December 31, 20162020 and 2015,2019, and for each of the years in the three-year period ended December 31, 2016,2020, and management’s assessment of the effectiveness of internal control over financial reporting as of December 31, 2020 have been incorporated by reference herein and in the registration statement in reliance upon the reportsreport of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. The audit report covering the December 31, 2020 consolidated financial statements refers to a change in the Company’s method of accounting for leases due to the adoption of Financial Accounting Standards Board Accounting Standards Codification Topic 842, Leases, as discussed in Note 2 to the consolidated financial statements.

WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informationreporting requirements of the Securities Exchange Act of 1934, as amended, and are required to file annual, quarterly and current reports, proxy statements information statements and other information with the SEC. You may read and copy this information, for a copying fee,SEC filings are available at the SEC’s Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549 on official business days during the hours of 10:00 a.m. to 3:00 p.m. Please call the SEC at 1-800-SEC-0330 for more information on its Public Reference Room. Our SEC filings are also available to the public from commercial document retrieval services, and at the website maintained by the SECweb site at http://www.sec.gov.

This prospectus is only part of a registration statement on Form S-3 that we have filed with the SEC under the Securities Act of 1933, as amended, and therefore omits certain information contained in the registration statement. We have also filed exhibits and schedules with the registration statement that are excluded from this prospectus, and you should refer to the applicable exhibit or schedule for a complete description of any statement referring to any contract or other document.

We maintain a website at http:https://www.aerogel.com, through which you can access our filings with the SEC. Information containedSEC filings. The information set forth on or accessible from our website doesis not constitute part of this prospectus. We have included our website address in this prospectus solely as an inactive textual reference.

This prospectus is part of a registration statement that we filed with the SEC. The registration statement contains more information than this prospectus regarding us and the securities, including exhibits and schedules. You can obtain a copy of the registration statement from the SEC at any address listed above or from the SEC’s website.


INFORMATION INCORPORATEDINCORPORATION OF DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” into this prospectus information that we have filedfile with the SEC. This means we canthem. Incorporation by reference allows us to disclose important information to you by referring you to those other documents that contain that information.documents. The information incorporated by reference is consideredan important part of this prospectus, and information that we file later with the SEC will automatically update and supersede this information. We filed a registration statement on Form S-3 under the Securities Act of 1933, as amended, with the SEC with respect to the securities we may offer pursuant to this prospectus. We incorporateThis prospectus omits certain information contained in the registration statement, as permitted by the SEC. You should refer to the registration statement, including the exhibits, for further information about us and the securities we may offer pursuant to this prospectus. Statements in this prospectus regarding the provisions of certain documents filed with, or incorporated by reference in, the registration statement are not necessarily complete and each statement is qualified in all respects by that reference. Copies of all or any part of the registration statement, including the documents listed below:incorporated by reference or the exhibits, are available at the SEC’s website at http://www.sec.gov. The documents we are incorporating by reference are:

(1)

Ourour Annual Report on Form 10-K for the fiscal year ended December 31, 20162020 that we filed with the SEC on March 2, 2017;12, 2021;

(2)

Thethe portions of our definitive proxy statement on Schedule 14A filed with the SEC on April 26, 201724, 2020 that are deemed “filed” with the SEC under the Exchange Act;

(3)

Our Quarterlyour Current Report on Form 10-Q for the fiscal quarter ended March 31, 20178-K that we filed with the SEC on May 5, 2017, our Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2017 that we filed with the SEC on August 4, 2017 and our Quarterly Report on Form 10-Q for the fiscal quarter ended September 30, 2017 that we filed with the SEC on November 3, 2017;

(4)

Our Current Reports on Form 8-K that we filed with the SEC on January 30, 2017, June 14, 2017, August 3, 2017 and October 2, 2017February 9, 2021 (except for the information furnished under Items 2.02 or 7.01 and the exhibits furnished thereto);

(5)

the description of our common stock contained in our Registration Statement on Form 8-A filed on June 6, 2014, including any amendment or report filed for the purpose of updating such description; and

all reports and other documents subsequently filed by us pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the date of this prospectus and prior to the termination or completion of the offering of securities under this prospectus shall be deemed to be incorporated by reference in this prospectus and to be a part hereof from the date of filing such reports and other documents.

The SEC file number for each of the documents listed above is 001-36481.

In addition, all reports and other documents filed by us pursuant to the Exchange Act after the date of the initial registration statement and prior to effectiveness of the registration statement shall be deemed to be incorporated by reference into this prospectus.

(6)

all reports and other documents subsequently filed by us pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act after the date of this prospectus and prior to the termination or completion of the offering of securities under this prospectus shall be deemed to be incorporated by reference in this prospectus and to be a part hereof from the date of filing such reports and other documents.

Any statement contained in this prospectus or in a document incorporated or deemed to be incorporated by reference into this prospectus will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or any other subsequently filed document that is deemed to be incorporated by reference into this prospectus modifies or supersedes the statement. Any statementsstatement so modified or superseded shallwill not be deemed, except as so modified or superseded, to constitute a part of this prospectus.

You may request, a copy of these documents, orally or in writing, whicha copy of any or all of the documents incorporated herein by reference. These documents will be provided to you at no cost, by contacting:

Aspen Aerogels, Inc.

Attn: Investor Relations,

30 Forbes Road, Building B,

Northborough, Massachusetts, 01532

Attention: Investor Relations

Telephone: (508) 691-1111

You may also access these documents on our website, http:https://www.aerogel.com.

You should rely only on information contained in, or incorporated by reference into, this prospectus and any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus or incorporated by reference in this prospectus. We are not making offers to sell the securities in any jurisdiction in which such an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make such offer or solicitation.


PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14.

Other Expenses of Issuance and Distribution

The following table sets forth an itemization of the fees andvarious expenses, incurred and to be incurredall of which we will pay, in connection with the registrationissuance and distribution of the securities being registered hereby, allregistered. All of which will be borne by us. Except forthe amounts shown are estimated except the SEC registration fee, all amounts are estimates.Registration Fee.

 

Description

 

Amount

 

SEC registration fee

 

$

3,672.02

 

Printing expense

 

 

1,000.00

 

Accounting fees and expenses

 

 

20,000.00

 

Legal fees and expenses

 

 

50,000.00

 

Total expenses

 

$

74,672.02

 

SEC Registration Fee

  $27,275 

Printing and Engraving Expenses

   * 

Legal Fees and Expenses

   * 

Accounting Fees and Expenses

   * 

Transfer Agent and Registrar Fees

   * 

Miscellaneous

   * 
  

 

 

 

Total

   * 

 

*

Fees depend on number of issuances and amount of securities sold and accordingly cannot be estimated at this time.

Item 15.

Indemnification of Directors and Officers

Delaware Law

Our restated certificateGeneral Corporation Law. Subsection (a) of incorporation and restated by-laws provideSection 145 of the Delaware General Corporation Law (the “DGCL”) provides that eacha corporation may indemnify any person who was or is made a party or is threatened to be made a party to any threatened, pending or is otherwise involved (including, without limitation, as a witness) in anycompleted action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation) by reason of the fact that he or she is or was onea director, officer, employee or agent of our directors or officersthe corporation, or is or was serving at ourthe request of the corporation as a director, officer, employee or trusteeagent of another corporation, or of a partnership, joint venture, trust or other enterprise, including service with respect to an employee benefit plan, whether the basis of such proceeding is alleged action in an official capacity as a director, officer or trustee or in any other capacity while serving as a director, officer or trustee, shall be indemnified and held harmless by us to the fullest extent authorized by the Delaware General Corporation Law against all expense, liability and loss (including attorneys’ fees, judgments, fines, ERISA excise taxes or penalties and amounts paid in settlement) reasonably incurred or suffered by such.

Section 145 of the Delaware General Corporation Law permits a corporation to indemnify any director or officer of the corporation against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by him in connection with anysuch action, suit or proceeding brought by reason of the fact that such person is or was a director or officer of the corporation, if such personhe acted in good faith and in a manner that he or she reasonably believed to be in or not opposed to the best interests of the corporation, and, with respect to any criminal action or proceeding, if he or she had no reasonable cause to believe his or her conduct was unlawful. InSection 145 of the DGCL further provides that a derivativecorporation similarly may indemnify any such person serving in any such capacity who was or is a party or is threatened to be made a party to any threatened, pending or completed action (i.e., one broughtor suit by or on behalfin the right of the corporation), indemnification may be provided only forcorporation to procure a judgment in its favor, against expenses (including attorneys’ fees) actually and reasonably incurred by any director or officer in connection with the defense or settlement of such an action or suit if such personhe acted in good faith and in a manner that he or she reasonably believed to be in or not opposed to the best interests of the corporation and except that no indemnification shall be provided ifmade in respect of any claim, issue or matter as to which such person shall have been adjudged to be liable to the corporation unless and only to the extent that the Delaware Court of Chancery Court or thesuch other court in which thesuch action or suit was brought shall determine upon application that, despite the adjudication of liability but in view of all of the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses despitewhich the Court of Chancery or such adjudicationother court shall deem proper.

Restated Certificate of liability.

Pursuant to Section 102(b)(7) of the Delaware General Corporation Law, Article VI of ourIncorporation and Restated Bylaws. Our restated certificate of incorporation eliminateslimits the liability of our directors and officers to the fullest extent permitted by Delaware law. Our restated certificate of incorporation and restated bylaws also provide that we will indemnify and advance expenses to any of our directors and officers who, by reason of the fact that he or she is one of our officers or directors, is involved in a legal proceeding of any nature. We will repay certain expenses incurred by a director toor officer in connection with any civil, criminal, administrative or investigative action or proceeding, including actions by us or in our stockholders for monetary damages for such a breach of fiduciary duty as aname. Such indemnifiable expenses include, to the maximum extent permitted by law, attorney’s fees, judgments, fines, ERISA excise taxes, penalties, settlement amounts and other expenses reasonably incurred in connection with legal proceedings. A director except for liabilities arising:

from any breach of the director’s duty of loyaltyor officer will not receive indemnification if he or she is found not to us or our stockholders;

from acts or omissions nothave acted in good faith and in a manner he or which involve intentional misconductshe reasonably believed to be in, or a knowing violation of law;not opposed to, our best interest.

under Section 174 of the Delaware General Corporation Law; and

from any transaction from which the director derived an improper personal benefit.

II-1


Indemnification Agreements.We have entered into indemnification agreements with each of our non-employee directors and with certain executive officers, in additionofficers. These agreements provide that we will, among other things, indemnify and advance expenses to the indemnification provided for in our restated certificate of incorporation and restated by-laws, and intend to enter into indemnification agreements with any new directors and executive officers for certain expenses, including attorneys’ fees, judgments, fines and settlement amounts incurred by any such person in the future. We have purchased and intend to maintain insurance on behalfany investigation, action or proceeding, including any action by us arising out of any person who is or was asuch person’s services as our director or officer, againstor any loss arising from any claim asserted against himother company or herenterprise to which the person provides services at our request. We believe that these provisions and incurred by him or heragreements are necessary to attract and retain qualified persons as directors and officers.

Insurance Policies. We have obtained director and officer liability insurance to cover liabilities our directors and officers may incur in any such capacity, subjectconnection with their services to certain exclusions.us.

The foregoing discussion of our restated certificate of incorporation, restated by-laws,bylaws, indemnification agreements, indemnity agreement, and Delaware law is not intended to be exhaustive and is qualified in its entirety by such restated certificate of incorporation, restated by-laws,bylaws, indemnification agreements, indemnity agreement, or law.

Reference is made to our undertakings in Item 17 with respect to liabilities arising under the Securities Act.

Item 16.

Exhibits

EXHIBIT INDEX

 

Exhibit

Number

Exhibit Description

Filed

with this

Report

Incorporated by

Reference

herein from

Form or
Schedule

Filing Date

Filing
Date

SEC
File/Reg.

Number

  4.1

  1.1*

Form of Underwriting Agreement.

  3.1Restated Certificate of Incorporation of the Registrant, as filed with the Secretary of State of the State of Delaware on June  18, 2014.

Form 8-K


(Exhibit 3.2)3.2


) 

6/19/14

001-36481

  4.2

  3.2

Restated Bylaws of Aspen Aerogels, Inc.


Form 8-K


(Exhibit 3.3)3.3


) 

6/19/14

001-36481

  4.3

  4.1

Form of common stock certificate.


Amendment
No. 1 to Form S-1

(Exhibit 4.1)4.1


) 

5/14/14

333-195523

  4.4

  4.2*

Form of warrantCertificate of Designation with respect to purchase common stock issued by the Registrant in connection with the 2010 subordinated note and warrant financing.

preferred stock.

Form S-1

(Exhibit 4.6)

4/28/14

333-195523

  4.5

  4.3

Sixth amended and restated registration rights agreement, dated as of June  11, 2012, by and among the Registrant and the investors named therein, as amended.


Form S-1


(Exhibit 4.8)4.8


) 

4/28/14

333-195523

  4.4Description of Securities.

  5.1

Form 10-K

(Exhibit 4.3


)

3/6/20001-36481
  4.5*Form of Senior Debt Security.
  4.6*Form of Subordinated Debt Security.
  4.7Form of Senior Indenture.

Form S-3

(Exhibit 4.6


)

8/31/18333-227158
  4.8Form of Subordinated Indenture.

Form S-3

(Exhibit 4.7


8/31/18333-227158

  4.9*Form of Warrant Agreement and Warrant Certificate.
  4.10*Form of Rights Agreement and Right Certificate.
  4.11*Form of Unit Agreement and Unit.
  5.1Opinion of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. with respect to the legality of the securities being registered.

X

X

23.1

Consent of KPMG LLP.

X

X

23.2

Consent of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. (included in Exhibit 5.1).

X

X

24.1

Powers of Attorney (included on signature page to this registration statement).

X
25.1*The Statement of Eligibility on Form T-1 under the Trust Indenture Act of 1939, as amended, of the Trustee under the Senior Indenture will be incorporated herein by reference from a subsequent filing in accordance with Section 305(b)(2) of the Trust Indenture Act of 1939.
25.2*The Statement of Eligibility on Form T-1 under the Trust Indenture Act of 1939, as amended, of the Trustee under the Subordinated Indenture will be incorporated herein by reference from a subsequent filing in accordance with Section 305(b)(2) of the Trust Indenture Act of 1939.

*

X

To be subsequently filed, if applicable, by an amendment to this registration statement or by a Current Report on Form 8-K.

II-2


Item 17.

Undertakings

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Sectionsection 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20 percenta 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement; and

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement.statement;

Provided,provided, however that: Paragraphs, that paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to section 13 or section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

(2) That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

(4) That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i) Each prospectus filed by the Registrantregistrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5), or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii), or (x) for the purpose of providing the information required by Sectionsection 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof; provided,thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such

II-3


effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

(5) That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii )Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

(b) That, for purposes of determining any liability under the Securities Act:

(1) The information omitted from the form of prospectus filed as part of the registration statement in reliance upon Rule 430A and contained in the form of prospectus filed by the registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the Securities Act shall be deemed to be part of the registration statement as of the time it was declared effective; and

(2) Each post-effective amendment that contains a form of prospectus shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c) The undersigned registrant hereby undertakes that, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

(c)(d) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant, pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the SECSecurities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

(e) The undersigned registrant hereby undertakes to file an application for the purpose of determining the eligibility of the trustee to act under subsection (a) of Section 310 of the Trust Indenture Act (“Act”) in accordance with the rules and regulations prescribed by the Commission under section 305(b)(2) of the Act.


II-4


SIGNATURESSIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrantregistrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the Towncity of Northborough, Commonwealth of Massachusetts, on November 7, 2017.March 12, 2021.

 

ASPEN AEROGELS, INC.

By:

By:  /s/

/s/ Donald R. Young

Donald R. Young

President and Chief Executive Officer

SIGNATURES AND POWER OF ATTORNEY

We, the undersigned officers and directors of Aspen Aerogels, Inc., hereby severally constitute and appoint Donald R. Young, and John F. Fairbanks, and each of them singly (with full power to each of them to act alone), our true and lawful attorneys-in-fact and agents, with full power of substitution and resubstitution in each of them foror him and in his name, place and stead, and in any and all capacities, to sign any and all amendments (including post-effective amendments) to this registration statement (or any other registration statement for the same offering that is to be effective upon filing pursuant to Rule 462(b) under the Securities Act of 1933), and to file the same, with all exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite or necessary to be done in and about the premises, as full to all intents and purposes as she or he might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or any of them or their or her or his substitute or substitutes may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed below by the following persons in the capacities and on the dates indicated.

 

Signature

Title

Date

Name

Title

Date

/s/ Donald R. Young

Donald R. Young

President, Chief Executive Officer

and Director (Principal Executive

Officer) and Director

November 7, 2017

March 12, 2021

/s/ John F. Fairbanks

John F. Fairbanks

Vice President, Chief Financial Officer and Treasurer (Principal

Financial Officer and Principal

Accounting Officer)

March 12, 2021

November 7, 2017/s/ William P. Noglows

William P. Noglows

Director (Chairman)

March 12, 2021

/s/ Rebecca B. Blalock

Rebecca B. Blalock

Director

March 12, 2021

/s/ Robert M. Gervis

Robert M. Gervis

Director

March 12, 2021

/s/ Steven R. Mitchell

Steven R. Mitchell

Director

March 12, 2021

Signature

Title

Date

/s/ Mark L. Noetzel

Mark L. Noetzel

Chairman of the Board

November 7, 2017

/s/ Rebecca A. Blalock
Rebecca Blalock

Director

November 7, 2017

March 12, 2021

/s/ Robert M. Gervis
Robert M. Gervis

Director

November 7, 2017

/s/ Steven R. Mitchell
Steven R. Mitchell

Director

November 7, 2017

/s/ William P. Noglows
William P. Noglows

Director

November 7, 2017

/s/ Richard F. Reilly

Richard F. Reilly

Director

November 7, 2017

March 12, 2021

 

II-542