X0508 4 2025-03-05 false 0001145986 ASPEN AEROGELS INC ASPN 0001929494 Johnson Virginia C/O ASPEN AEROGELS, INC., 30 FORBES ROAD, BLDG B NORTHBOROUGH MA 01532 false true false false CLO, GC, Secretary & CCO false Common Stock 2025-03-05 4 F false 936 7.84 D 26196 D Common Stock 2025-03-05 4 A false 26307 0 A 52503 D Stock Options (Right to Buy) 7.84 2025-03-05 4 A false 37804 0 A 2035-03-05 Common Stock 37804 37804 D Performance Share Units 2025-03-05 4 A false 52614 0 A 2028-03-05 Common Stock 52614 52614 D Shares withheld by Registrant to satisfy the minimum statutory tax withholding requirements on vesting of Restricted Stock Units ("RSUs"). 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 5, 2026, an additional one-third of the shares on March 5, 2027 and the remaining one-third of the shares on March 5, 2028. Represents 7,843 shares of Common Stock and 44,660 RSUs. The options vest as to one-third of the shares on March 5, 2026, an additional one-third of the shares on March 5, 2027 and the remaining one-third of the shares on March 5, 2028. Each performance share unit ("PSU") represents a contingent right to receive one share of Common Stock upon vesting. The PSUs vest on March 5, 2028, following the completion of the performance period, which begins on January 1, 2025 and ends on December 31, 2027. Ranging between 0-200% of the target number of PSUs (as reflected in Table II above), the PSUs vest based on the total shareholder return of Common Stock relative to the total stockholder return of the components of the Russell 2000 Index. /s/ Kristen Brown, Attorney-in-Fact 2025-03-07