Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 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 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES 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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(Print or Type Responses)

1. Name and Address of Reporting Person * Wood River Capital, LLC 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 _____ Officer (give title below) _____ Other (specify below) Former 10% Owner (Last) (First) (Middle) 4111 E. 37TH STREET NORTH 3. Date of Earliest Transaction (Month/Day/Year) 09/23/2026 (Street) WICHITA, KS 67220 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) 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 09/23/2026 S 12,280,426 D $4.73(1) 0 D(2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 Underlying Securities (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 of Derivative Security: 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

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Wood River Capital, LLC 4111 E. 37TH STREET NORTH WICHITA, KS 67220				Former 10% Owner
Koch, Inc. 4111 E. 37TH STREET NORTH WICHITA, KS 67220		X

Signatures

Wood River Capital, LLC /s/ Adam Schaeffer, Vice President and Secretary		09/24/2026
**Signature of Reporting Person		Date
Koch, Inc. /s/ Adam Fitzsimmons, Assistant Secretary		09/24/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	The sale was executed in a single block trade at $4.73 per share.
(2)	Wood River is beneficially owned by SCC Holdings, LLC ("SCC"), SCC is beneficially owned by KIM, LLC ("KIM"), KIM is beneficially owned by Koch Investments Group, LLC ("KIG"), KIG is beneficially owned by Koch Investments Group Holdings, LLC ("KIGH"), and KIGH is beneficially owned by Koch Industries, Inc. ("Koch Industries"), in each case by means of ownership of all voting equity instruments. Koch Industries, SCC, KIM, KIG, and KIGH may be deemed to beneficially own the shares of the Issuer's common stock beneficially owned by Wood River by virtue of (i) Koch Industries' beneficial ownership of KIGH, (ii) KIGH's beneficial ownership of KIG, (iii) KIG's beneficial ownership of KIM, (iv) KIM's beneficial ownership of SCC and (v) SCC's beneficial ownership of Wood River.

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