[Form 4] Aspen Aerogels, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Stephanie Pittman, Chief Human Resources Officer of Aspen Aerogels, Inc. (ASPN), reported a Form 4 filing disclosing a transaction on 09/05/2025. The filing shows 1,581 shares of Common Stock were disposed of at a price of $6.61 per share. Following the transaction, Ms. Pittman beneficially owns 42,257 shares in total, comprised of 9,196 shares of Common Stock and 33,061 unvested Restricted Stock Units (RSUs). The filing states the 1,581 shares were withheld by the company to satisfy minimum statutory tax withholding on RSU vesting.

Positive

• Clear disclosure of the withholding transaction, including share count and price
• Compliance with Section 16 reporting via timely Form 4 filing
• Explanatory note states shares were withheld for statutory tax obligations (administrative, not a market sale)

Negative

• Reduction in direct ownership by 1,581 shares following tax withholding
• Majority of holdings (33,061) are unvested RSUs and not immediately liquid or voting shares

Insights

Compensation Analyst

TL;DR: Routine tax-withholding on RSU vesting; reduces reported beneficial ownership but reflects standard payroll tax treatment.

The Form 4 records a common post-vesting mechanics: the company withheld 1,581 shares to satisfy tax obligations tied to RSU vesting. This is not an open-market sale by the officer but an internal share withholding event recorded as a disposition at $6.61 per share. Beneficial ownership after the event totals 42,257 shares, including 33,061 RSUs which remain unvested and subject to future vesting and potential further withholding. The disclosure is granular and consistent with typical executive equity compensation administration.

Corporate Governance Expert

TL;DR: Disclosure appears timely and compliant; transaction is administrative and not indicative of strategic insider sale.

The filing identifies the reporting person as an officer (CHRO) and indicates the use of a power of attorney (Exhibit 24). The transaction code 'F' and the explanatory remark confirm share withholding for taxes rather than a voluntary sale. From a governance standpoint, the Form 4 properly reports the change in beneficial ownership and the mix of direct shares versus RSUs, supporting transparency around executive compensation accounting.

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
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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^*

Pittman Stephanie

(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 Human Resources Officer

3. Date of Earliest Transaction (Month/Day/Year)
09/05/2025

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	09/05/2025		F		1,581(1)	D	$6.61	42,257(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 9,196 shares of Common Stock and 33,061 RSUs.

Remarks:

Power of Attorney is attached hereto as Exhibit 24.

	/s/ Stephanie Pittman, Attorney-in-Fact	09/08/2025
	** 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 transaction did Aspen Aerogels (ASPN) Chief Human Resources Officer report on Form 4?

The Form 4 reports a disposition of 1,581 shares on 09/05/2025 at a price of $6.61 per share.

Why were 1,581 shares disposed of by Stephanie Pittman?

The filing explains the shares were withheld by the registrant to satisfy minimum statutory tax withholding on the vesting of RSUs.

How many shares does Stephanie Pittman beneficially own after the transaction?

She beneficially owns 42,257 shares following the reported transaction, consisting of 9,196 common shares and 33,061 RSUs.

Does the Form 4 indicate a market sale by the officer?

No. The transaction code and explanation indicate an administrative withholding for taxes, not an open-market sale.

When was the Form 4 signed and by whom?

The form is signed via power of attorney: /s/ Stephanie Pittman, Attorney-in-Fact with a signature date of 09/08/2025.