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ASPN SCHEDULE 13D/A: Activist campaign

An amendment to a Schedule 13D was

Filed with the SEC on · accession 0001193125-26-401393

ASPN filed a SCHEDULE 13D/A (schedule 13d/a) with the SEC on Sep 24, 2026. An amendment to a Schedule 13D was filed for Aspen Aerogels Inc, indicating a change in a previously reported activist or large shareholder position. The stock moved -6.7% by the first close after the filing.

Summary of the filing

An amendment to a Schedule 13D was filed for Aspen Aerogels Inc, indicating a change in a previously reported activist or large shareholder position. The filing text does not disclose specific ownership percentages or stated intentions.

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Key details

Subject companyAspen Aerogels Inc

How ASPN stock reacted

Close before

$5.68

Sep 23, 2026

First close after

-6.69%

$5.30

5 trading days

-3.52%

$5.48

Since filing

-13.56%

$4.91

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Frequently asked questions

What did ASPN file with the SEC on Sep 24, 2026?

ASPN filed a SCHEDULE 13D/A (Activist campaign). An amendment to a Schedule 13D was filed for Aspen Aerogels Inc, indicating a change in a previously reported activist or large shareholder position. The filing text does not disclose specific ownership percentages or stated intentions.

What does a activist campaign mean for ASPN stock?

A settlement removes uncertainty; the stock often reacts to whether the amount is bigger or smaller than investors expected.

How do I read a SCHEDULE 13D/A?

A report the company filed with the SEC (the US market regulator). Start with the summary, then the key amounts and names. Compare it with the company’s earlier filings.

Why are SEC filings important?

Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A SCHEDULE 13D/A (schedule 13d/a): A report the company filed with the SEC (the US market regulator).

How did ASPN stock react to this filing?

ASPN closed at $5.68 before the filing and $5.30 on Sep 24, 2026 (-6.69%). Five trading days later: $5.48 (-3.52%).

Other ASPN SEC filings

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