SEC Form 4 Filing for Glenn E. Deegan

This filing reports a transaction by Glenn E. Deegan, Chief Administrative Officer, General Counsel, and Corporate Secretary of Aspen Aerogels Inc. On September 30, 2026, Mr. Deegan disposed of 1143 shares of Common Stock. The disposal was to satisfy tax withholding requirements upon the vesting of Restricted Stock Units. The transaction price was $5.48 per share. Following this transaction, Mr. Deegan owns 66,033 shares of Common Stock, including 2,748 shares and 63,285 RSUs.