X0306 4 2021-03-11 0 0001145986 ASPEN AEROGELS INC ASPN 0001610273 Whitaker Corby C C/O ASPEN AEROGELS, INC. 30 FORBES ROAD, BUILDING B NORTHBOROUGH MA 01532 0 1 0 0 SVP, Sales and Marketing Common Stock 2021-03-11 4 M 0 14500 7.54 A 124680 D Common Stock 2021-03-11 4 S 0 14500 22.65 D 110180 D Stock Option (Right to Buy) 7.54 2021-03-11 4 M 0 14500 0.00 D 2025-03-11 Common Stock 14500 4258 D Represents 105,846 shares of Common Stock and 18,834 Restricted Stock Units. Average price with actual price ranging from $22.25 and $22.865. The reporting person will provide to the staff of the Securities and Exchange Commission, the issuer, or any security holder of the issuer, upon request, full information regarding the number of shares sold at each separate price. Represents 91,346 shares of Common Stock and 18,834 Restricted Stock Units. This option is fully vested and exercisable. /s/ Poongunran Muthukumaran, Attorney-in-Fact 2021-03-12