ASPN

Form 8-KFalse000114598600011459862026-02-252026-02-25iso4217:USDxbrli:sharesiso4217:USDxbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported):  February 25, 2026

ASPEN AEROGELS, INC.

(Exact name of registrant as specified in its charter)

Delaware001-3648104-3559972 (State or Other Jurisdiction of Incorporation)(Commission File Number)(I.R.S. Employer Identification No.)

30 Forbes Road, Building B Northborough, Massachusetts01532 (Address of Principal Executive Offices)(Zip Code)

Registrant's Telephone Number, Including Area Code: (508) 691-1111

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each classTrading Symbol(s)Name of each exchange on which registered Common StockASPNThe New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging 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 13(a) of the Exchange Act. ☐

Item 2.02. Results of Operations and Financial Condition.

On February 25, 2026, Aspen Aerogels, Inc. announced its financial results for the fourth quarter and fiscal year 2025, which ended December 31, 2025, and also discussed business developments. A copy of the press release containing such announcement is attached hereto as Exhibit 99.1.

The information set forth in the press release, except for the information set forth under the headings “Financial Outlook” and “About Aspen Aerogels, Inc.,” together with the forward-looking statement disclaimer at the end of the press release, is incorporated by reference into this Item 2.02 of this Current Report on Form 8-K.

Item 7.01. Regulation FD Disclosure.

The information set forth under the headings “Financial Outlook” and “About Aspen Aerogels, Inc.,” together with the forward-looking statement disclaimer at the end of the press release, is incorporated by reference into this Item 7.01 of this Current Report on Form 8-K.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number Description

99.1 Press Release issued by Aspen Aerogels, Inc. on February 25, 2026 104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

The press release may contain hypertext links to information on our website. The information on our website is not incorporated by reference into this Current Report on Form 8-K and does not constitute a part of this Form 8-K.

The information contained in this Current Report on Form 8-K and Exhibit 99.1 attached hereto is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities under that Section, nor shall it be deemed incorporated by reference into any registration statement or other filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ASPEN AEROGELS, INC.

Date: February 25, 2026By: /s/ Grant Thoele Name:Grant Thoele Title:  Chief Financial Officer and Treasurer

Form 8-KFalse000114598600011459862025-11-062025-11-06iso4217:USDxbrli:sharesiso4217:USDxbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported):  November 6, 2025

ASPEN AEROGELS, INC.

(Exact name of registrant as specified in its charter)

Delaware001-3648104-3559972 (State or Other Jurisdiction of Incorporation)(Commission File Number)(I.R.S. Employer Identification No.)

30 Forbes Road, Building B Northborough, Massachusetts01532 (Address of Principal Executive Offices)(Zip Code)

Registrant's Telephone Number, Including Area Code: (508) 691-1111

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each classTrading Symbol(s)Name of each exchange on which registered Common StockASPNThe New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging 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 13(a) of the Exchange Act. ☐

Item 2.02. Results of Operations and Financial Condition.

On November 6, 2025, Aspen Aerogels, Inc. announced its financial results for the third quarter of 2025, which ended September 30, 2025, and also discussed business developments. A copy of the press release containing such announcement is attached hereto as Exhibit 99.1.

The information set forth in the press release, except for the information set forth under the headings “2025 Financial Outlook” and “About Aspen Aerogels, Inc.,” together with the forward-looking statement disclaimer at the end of the press release, is incorporated by reference into this Item 2.02 of this Current Report on Form 8-K.

Item 7.01. Regulation FD Disclosure.

The information set forth under the headings “2025 Financial Outlook” and “About Aspen Aerogels, Inc.,” together with the forward-looking statement disclaimer at the end of the press release, is incorporated by reference into this Item 7.01 of this Current Report on Form 8-K.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number Description

99.1 Press Release issued by Aspen Aerogels, Inc. on November 6, 2025 104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

The press release may contain hypertext links to information on our website. The information on our website is not incorporated by reference into this Current Report on Form 8-K and does not constitute a part of this Form 8-K.

The information contained in this Current Report on Form 8-K and Exhibit 99.1 attached hereto is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities under that Section, nor shall it be deemed incorporated by reference into any registration statement or other filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ASPEN AEROGELS, INC.

Date: November 6, 2025By: /s/ Grant Thoele Name:Grant Thoele Title:  Chief Financial Officer and Treasurer

Form 8-KFalse000114598600011459862025-08-072025-08-07iso4217:USDxbrli:sharesiso4217:USDxbrli:shares

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 Date of Report (Date of earliest event reported):  August 7, 2025

ASPEN AEROGELS, INC.

(Exact name of registrant as specified in its charter)

Delaware001-3648104-3559972 (State or Other Jurisdiction of Incorporation)(Commission File Number)(I.R.S. Employer Identification No.)

30 Forbes Road, Building B Northborough, Massachusetts01532 (Address of Principal Executive Offices)(Zip Code)

Registrant's Telephone Number, Including Area Code: (508) 691-1111

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) Securities registered pursuant to Section 12(b) of the Act: Title of each classTrading Symbol(s)Name of each exchange on which registered Common StockASPNThe New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging 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 13(a) of the Exchange Act. ☐

Item 2.02. Results of Operations and Financial Condition. On August 7, 2025, Aspen Aerogels, Inc. announced its financial results for the second quarter of 2025, which ended June 30, 2025, and also discussed business developments. A copy of the press release containing such announcement is attached hereto as Exhibit 99.1. The information set forth in the press release, except for the information set forth under the headings “Second Half of 2025 Financial Outlook,” “Aspen Announces CFO Transition to Internal Successor” and “About Aspen Aerogels, Inc.,” together with the forward-looking statement disclaimer at the end of the press release, is incorporated by reference into this Item 2.02 of this Current Report on Form 8-K.

Item 7.01. Regulation FD Disclosure. The information set forth under the headings “Second Half of 2025 Financial Outlook,” “Aspen Announces CFO Transition to Internal Successor” and “About Aspen Aerogels, Inc.,” together with the forward-looking statement disclaimer at the end of the press release, is incorporated by reference into this Item 7.01 of this Current Report on Form 8-K.

Item 9.01. Financial Statements and Exhibits. (d) Exhibits. Exhibit Number Description

99.1 Press Release issued by Aspen Aerogels, Inc. on August 7, 2025 104 Cover Page Interactive Data File (embedded within the Inline XBRL document) The press release may contain hypertext links to information on our website. The information on our website is not incorporated by reference into this Current Report on Form 8-K and does not constitute a part of this Form 8-K. The information contained in this Current Report on Form 8-K and Exhibit 99.1 attached hereto is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities under that Section, nor shall it be deemed incorporated by reference into any registration statement or other filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

ASPEN AEROGELS, INC.

Date: August 7, 2025By: /s/ Ricardo C. Rodriguez Name:Ricardo C. Rodriguez Title:  Chief Financial Officer and Treasurer