[Form 4] ASPEN AEROGELS INC Insider Trading Activity

Rhea-AI Filing Summary

Insider transaction summary for ASPN: Daniel Santhosh, Chief Accounting Officer of Aspen Aerogels, reported the disposition of 1,563 shares of common stock on 09/13/2025 at a price of $6.59 per share. The filing states these shares were withheld by the company to satisfy minimum statutory tax withholding on vesting of restricted stock units (RSUs). After the withholding, Mr. Santhosh beneficially owns a total of 16,316 shares/RSU-equivalents, composed of 3,761 shares of common stock and 12,555 RSUs. The Form 4 was signed by an attorney-in-fact on 09/15/2025.

Insights

Corporate Governance Expert

TL;DR: Routine tax-withholding on RSU vesting resulted in a small disposition; no change in role or control indicated.

The transaction is documented as a tax-withholding disposition of 1,563 shares tied to RSU vesting rather than a voluntary market sale. Such withholding is common practice and does not indicate an active change in insider ownership intent or corporate governance. The remaining reported beneficial position totals 16,316 shares/RSU equivalents, which should be tracked for future vesting schedules but is not by itself a material governance event.

Securities Analyst

TL;DR: Small disposition via withholding at $6.59 per share; transactional not strategic, limited market impact.

The disposition of 1,563 shares at $6.59 reflects employer tax-withholding on RSU vesting rather than a discretionary sale. For a reporting officer, this reduces outstanding shares held directly but leaves a combined beneficial stake of 16,316 units. Given the modest size of the withheld amount relative to typical company market caps, this filing is routine and unlikely to move investor valuation metrics.

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)
09/13/2025

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	09/13/2025		F		1,563(1)	D	$6.59	16,316(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. 1. Shares withheld by Registrant to satisfy minimum statutory tax withholding requirements on vesting of Restricted Stock Units ("RSUs").

2. 2. Represents 3,761 shares of Common Stock and 12,555 RSUs.

	/s/ Stephanie Pittman, Attorney-in-Fact	09/15/2025
	** 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.

FAQ

What did ASPN insider Daniel Santhosh report on Form 4?

The report shows 1,563 shares were withheld to satisfy tax withholding on RSU vesting and lists a beneficial ownership of 16,316 units (3,761 shares and 12,555 RSUs).

When was the transaction reported for ASPN insider activity?

The transaction date shown is 09/13/2025 and the Form 4 was signed on 09/15/2025.

What price was used for the withheld ASPN shares?

The filing lists a price of $6.59 per share for the 1,563 shares withheld.

Does this Form 4 indicate a sale by the insider for cash proceeds?

No. The filing explains the shares were withheld by the registrant for tax-withholding upon RSU vesting, not a discretionary open-market sale.

How many RSUs does the reporting person still hold for ASPN?

The filing reports 12,555 RSUs as part of the total 16,316 beneficial units remaining after withholding.