X0407 4 2023-06-01 0 0001145986 ASPEN AEROGELS INC ASPN 0001668364 Conte Kelley C/O. ASPEN AEROGELS, INC. 30 FORBES ROAD, BLDG B NORTHBOROUGH MA 01532 0 1 0 0 Senior Vice President, HR 0 Common Stock 2023-06-01 4 A 0 14684 0.00 A 128183 D Stock Option (Right to Buy) 6.81 2023-06-01 4 A 0 67537 0.00 A 2033-06-01 Common Stock 67537 67537 D Each Restricted Stock Unit ("RSU") represents the right to receive one share of Common Stock upon vesting. The RSUs vest as to one-third of the shares on March 8, 2024, an additional one-third of the shares on March 8, 2025 and the remaining one-third of the shares on March 8, 2026. Represents 56,424 shares of Common Stock, 18,169 RSUs and 53,590 shares of Restricted Stock. The options vest as to one-third of the shares on March 8, 2024, an additional one-third of the shares on March 8, 2025 and the remaining one-third of the shares on March 8, 2026. Power of Attorney is attached hereto as Exhibit 24. /s/ Virginia H. Johnson, Attorney-in-Fact 2023-06-02