X0306 4 2018-02-28 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 2018-02-28 4 A 0 25543 0.00 A 101426 D Common Stock 2018-02-28 4 F 0 3078 4.60 D 98348 D Common Stock 2018-03-01 4 F 0 2954 4.57 D 95394 D Stock Options (Right to Buy) 4.60 2018-02-28 4 A 0 52735 0.00 A 2028-02-28 Common Stock 52735 52735 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 February 28, 2019, an additional one-third of the shares on February 28, 2020, and the remaining one-third of the shares on February 28, 2021. Represents 21,926 shares of common stock and 79,500 restricted stock units. Shares withheld by Registrant to satisfy the minimum statutory tax withholding requirements on vesting of time-based restricted stock units. Represents 27,704 shares of common stock and 70,644 restricted stock units. Represents 33,939 shares of common stock and 61,455 restricted stock units. The options vest as to one-third of the shares on February 28, 2019, an additional one-third of the shares on February 28, 2020, and the remaining one-third of the shares on February 28, 2021. /s/ Poongunran Muthukumaran, Attorney-in-fact 2018-03-02