Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F1,F2	Jun 2, 2015	S	3,428	$7.0103	D	251,028	I	Held by Reservoir Capital Master Fund, L.P.
Common Stock^F3,F2	Jun 2, 2015	S	17,188	$7.0103	D	2,642,250	I	Held by Reservoir Capital Partners, L.P.
Common Stock^F4,F2	Jun 3, 2015	S	558	$6.7806	D	250,470	I	Held by Reservoir Capital Master Fund, L.P.
Common Stock^F5,F2	Jun 3, 2015	S	2,795	$6.7806	D	2,639,455	I	Held by Reservoir Capital Partners, L.P.
Common Stock	holding	—	—		—	7,727	D

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.00 to $7.08, inclusive. The reporting person undertakes to provide to Aspen Aerogels, Inc., any security holder of Aspen Aerogels, Inc. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (1) and footnotes (3), (4) and (5) to this Form 4.
F2The securities held by Reservoir Capital Partners, L.P. ("RCP") or Reservoir Capital Master Fund, L.P. ("RCMF") may be deemed to be beneficially owned by Craig A. Huff and Daniel Stern, who are the senior managing members (the "Reservoir Members") of RCGM, LLC ("RCGM"). RCGM is the managing member of Reservoir Capital Group, L.L.C. ("RCG"), which is the general partner of Reservoir Capital Partners (Cayman), L.P. ("RCP Cayman"), which is the sole member of RCP GP, LLC ("RCP GP"), and which is the general partner of RCP. RCG is the general partner of RCMF. Each of the Reservoir Members, RCGM, RCG, RCP Cayman and RCP GP disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein.
F3The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.00 to $7.08, inclusive.
F4The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.65 to $6.91, inclusive.
F5The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.65 to $6.91, inclusive.