Aspen Aerogels, Inc.

Item 7.01. Regulation FD Disclosure. Update on Incident at East Providence Facility As previously reported by Aspen Aerogels, Inc. (“Aspen” or the “Company”), an explosion occurred at Aspen’s manufacturing facility in East Providence, Rhode Island on the evening of April 8, 2026. The explosion damaged a portion of the facility’s production space and required the temporary cessation of operations. The investigation into the cause of the incident is ongoing. Preliminary reports indicate the explosion originated in a specific high-temperature oven. Eleven employees at the facility were transported to local medical facilities for evaluation and were subsequently released. As of April 21, 2026, the facility remains offline. The Company continues to work with the relevant authorities to execute a plan to resume operations. The Company maintains business interruption and property damage insurance and has initiated the claims process with its insurance carriers. The Company continues to analyze the potential impacts of the incident on the Company’s business, operations and financial performance, and expects to provide a further update in connection with its fiscal 2026 first quarter earnings release in early May.

Item 8.01. Other Events. The information set forth in Item 7.01 above is incorporated by reference into this Item 8.01 of this Current Report on Form 8-K.