Aspen Aerogels (ASPN) CAO has 986 shares withheld for RSU taxes

Rhea-AI Filing Summary

Aspen Aerogels Inc. Chief Accounting Officer P. Daniel Santhosh reported a small share disposal related to taxes rather than an open‑market sale. On the vesting of Restricted Stock Units (RSUs), 986 shares of common stock were withheld by the company at $3.27 per share to satisfy minimum statutory tax withholding requirements.

After this tax-withholding disposition, Santhosh’s holdings total 15,330 equity interests, consisting of 5,593 shares of common stock and 9,737 RSUs. This type of transaction is routine for executives when RSUs vest and does not reflect a discretionary buy or sell decision.

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

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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^*

Daniel Santhosh P

(Last) (First) (Middle)

C/O ASPEN AEROGELS, INC.,

30 FORBES ROAD, BLDG B

(Street)

NORTHBOROUGH MA 01532

(City) (State) (Zip)

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)
	Chief Accounting Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/05/2026

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

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

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

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	03/05/2026		F		986(1)	D	$3.27	15,330(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 5,593 shares of Common Stock and 9,737 RSUs.

Remarks:

Exhibit 24.1 - Power of Attorney

	/s/ Glenn Deegan, Attorney-in-Fact	03/06/2026
	** 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).
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FAQ

What insider transaction did ASPN’s Chief Accounting Officer report?

Aspen Aerogels’ Chief Accounting Officer reported a disposal of 986 common shares. The shares were withheld by the company at $3.27 each to cover minimum statutory taxes triggered by vesting Restricted Stock Units, rather than representing an open‑market sale decision.

Was the ASPN Form 4 transaction a normal buy or sell?

The ASPN Form 4 does not show a normal market buy or sell. It reports a tax-withholding disposition, where 986 vested RSU shares were withheld by Aspen Aerogels to pay required taxes, a common administrative step for equity compensation recipients.

How many Aspen Aerogels shares were used to cover taxes?

A total of 986 Aspen Aerogels common shares were used to cover taxes. These shares were automatically withheld by the company at a price of $3.27 per share when Restricted Stock Units vested, satisfying minimum statutory tax withholding obligations for the executive.

What are the Chief Accounting Officer’s holdings after this ASPN transaction?

Following the transaction, the Chief Accounting Officer holds 15,330 equity interests. This includes 5,593 shares of Aspen Aerogels common stock and 9,737 Restricted Stock Units, as disclosed, reflecting total beneficial holdings after the tax-withholding share disposition.

Does the ASPN Form 4 indicate a change in insider confidence?

The ASPN Form 4 reflects a routine tax-withholding event rather than a strategic trade. Shares were withheld automatically on RSU vesting to meet statutory tax obligations, so it does not, by itself, signal a change in insider sentiment or confidence about the company.

What does transaction code F mean in the ASPN Form 4 filing?

Transaction code F indicates payment of an exercise price or tax liability by delivering securities. In this ASPN filing, it shows 986 shares were withheld upon RSU vesting to satisfy minimum statutory tax requirements, not an elective open‑market stock sale by the insider.