Aspen Aerogels: 1,143 Deegan shares withheld for taxes

The reported transaction price was $5.48 per share for the shares withheld.

Rhea-AI Filing Summary

Aspen Aerogels Inc. (ASPN) reported that 1,143 of CAO, GC & Corp Secretary Glenn E. Deegan’s Common Stock shares were withheld on September 30, 2026, to satisfy minimum statutory tax withholding requirements on vesting of RSUs. His reported post-transaction position comprised 2,748 Common Stock shares and 63,285 RSUs.

Insider Trade Summary

Tax Withholding: 1,143 shares

Tax Withholding 1 txn

Insider DEEGAN GLENN E.

Role CAO, GC & Corp Secretary

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock F1, F2	1,143	$5.48	$6K

Holdings After Transaction: Common Stock — 66,033 shares (Direct)

Footnotes (2)

1. F1. Shares withheld by Registrant to satisfy the minimum statutory tax withholding requirements on vesting of Restricted Stock Units ("RSUs").
2. F2. Represents 2,748 shares of Common Stock and 63,285 RSUs.

Key Figures

Common Stock shares withheld: 1,143 shares Reported transaction price: $5.48 per share Common Stock shares after transaction: 2,748 shares +1 more

4 metrics

Common Stock shares withheld 1,143 shares September 30, 2026

Reported transaction price $5.48 per share September 30, 2026

Common Stock shares after transaction 2,748 shares Reported post-transaction position

RSUs after transaction 63,285 RSUs Reported post-transaction position

Key Terms

Restricted Stock Units (RSUs), minimum statutory tax withholding requirements, vesting

3 terms

Restricted Stock Units (RSUs) financial

"vesting of Restricted Stock Units ("RSUs")"

Restricted stock units (RSUs) are a type of company promise to give employees shares of stock in the future, usually after certain conditions like working for a set time. They are like a gift promised today that you receive later, which can become valuable if the company's stock price goes up. RSUs matter because they are a way companies reward employees and can be a significant part of compensation.

minimum statutory tax withholding requirements financial

"satisfy the minimum statutory tax withholding requirements"

vesting technical

"on vesting of Restricted Stock Units"

Vesting is the process by which you earn full ownership of something, like company stock or a retirement benefit, over time. It’s like earning the right to keep a gift piece by piece the longer you stay with a company, making sure employees stay committed before they receive all the benefits.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many ASPN shares were withheld for taxes?

Aspen Aerogels Inc. reported that 1,143 shares were withheld to satisfy minimum statutory tax withholding requirements on vesting of RSUs. The transaction was reported on September 30, 2026, at $5.48 per share.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Available on EDGAR 10/01/2026 - 05:00 PM Accepted by SEC EDGAR 10/01/2026 - 05:00 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

DEEGAN GLENN E.

(Last) (First) (Middle)

C/O ASPEN AEROGELS, INC.

30 FORBES ROAD, BLDG B

(Street)

NORTHBOROUGH MASSACHUSETTS 01532

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
ASPEN AEROGELS INC [ ASPN ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CAO, GC & Corp Secretary

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/30/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/30/2026		F		1,143(1)	D	$5.48	66,033(2)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Shares withheld by Registrant to satisfy the minimum statutory tax withholding requirements on vesting of Restricted Stock Units ("RSUs").

2. Represents 2,748 shares of Common Stock and 63,285 RSUs.

	/s/ Andrew Lauzon, Attorney-in-Fact	10/01/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)