ASPEN AEROGELS INC

During the fiscal quarter ended June 30, 2024, the following directors and executive officers adopted a “rule 10b5-1 trading arrangement” (as defined in Item 408 of Regulation S-K of the Exchange Act).

•

On May 16, 2024, Ricardo C. Rodriguez, Chief Financial Officer and Treasurer of the Company, adopted a Rule 10b5-1 Sales Plan. The plan is intended to satisfy the affirmative defense of Rule 10b5-1(c) and provides for the sale of up to an aggregate of 44,215 shares of our common stock until August 31, 2025.

•

On June 4, 2024, Donald R. Young, President and Chief Executive Officer of the Company and a director of the Company, adopted a Rule 10b5-1 Sales Plan. The plan is intended to satisfy the affirmative defense of Rule 10b5-1(c) and provides for the sale of up to an aggregate of 134,629 shares of our common stock until June 5, 2025.

•

On June 6, 2024, Steven R. Mitchell, adirector of the Company, adopted a Rule 10b5-1 Sales Plan. The plan is intended to satisfy the affirmative defense of Rule 10b5-1(c) and provides for the sale of up to an aggregate of 57,541 shares of our common stock until June 7, 2025.

Except as disclosed above, none of our directors or executive officers adopted, modified orterminated any contract, instruction or written plan for the purchase or sale of our securities that was intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) or any “non-Rule 10b5-1 trading arrangement” as such term is defined in Item 408(a) of Regulation S-K, during the fiscal quarter ended June 30, 2024.