ASPI Insider Sale: 75,000 Shares Disposed to Cover Taxes After 200,000-Vest

Rhea-AI Filing Summary

Moore Duncan, a director of ASP Isotopes Inc. (ASPI), reported the sale of 75,000 shares on 08/29/2025 at a weighted average price of $9.2831. After the sale he beneficially owned 994,553 shares. The filing states the sale included shares sold to satisfy income tax liabilities arising from the vesting of a previously granted restricted stock award for 200,000 shares. The weighted-average price represents multiple trades executed between $8.95 and $10.20. The Form 4 was signed by an attorney-in-fact on 09/03/2025. This disclosure records an insider disposition tied to tax withholding for a stock award.

Positive

• Sale was disclosed and explained as tax-related due to vesting, providing transparency to investors
• Reporting person retains substantial ownership with 994,553 shares reported after the transaction

Negative

• Director disposed of 75,000 shares, reducing direct holdings
• Vesting of 200,000 restricted shares created a tax liability requiring share sales

Insights

Financial Analyst

TL;DR: Insider sale was tax-driven and reduces direct holdings modestly; no indicated change in company guidance or operations.

The Form 4 documents a director-initiated sale of 75,000 shares at a weighted average of $9.2831, reducing reported beneficial ownership to 994,553 shares. The filing explicitly states the purpose was to satisfy income taxes from the vesting of 200,000 restricted shares. Such transactions are commonly administrative in nature and do not by themselves signal operational or financial changes at the company.

Corporate Governance Expert

TL;DR: This is a routine, disclosed disposition tied to equity award vesting; documentation and signature by attorney-in-fact meet filing norms.

The disclosure identifies the reporting person as a director and shows the sale was executed on 08/29/2025 with footnotes clarifying price range and tax-related motive. The reporting and signature elements appear complete, including an attorney-in-fact signature dated 09/03/2025. From a governance standpoint, the filing provides required transparency about insider transactions related to compensation events.

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^*

Moore Duncan

(Last) (First) (Middle)

C/O ASP ISOTOPES INC.

601 PENNSYLVANIA AVENUE NW, SUITE 900

(Street)

WASHINGTON, DC DC 20004

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
ASP Isotopes Inc. [ ASPI ]

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

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
08/29/2025

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	08/29/2025		S(1)		75,000	D	$9.2831(2)	994,553	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. The sale of shares reported in this Form 4 includes an amount for the purpose of satisfying the reporting person's income tax liabilities resulting from the vesting of a previously granted restricted stock award for 200,000 shares pursuant to an issuer equity incentive plan.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.95 to $10.20, inclusive. The reporting person undertakes to provide ASP Isotopes Inc. (the "Company"), any stockholder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in Footnote 2.

Remarks:

	/s/ Donald Ainscow, as attorney-in-fact	09/03/2025
	** 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 Moore Duncan report on Form 4 for ASPI?

The Form 4 reports the sale of 75,000 shares on 08/29/2025 at a weighted average price of $9.2831.

Why were shares sold according to the Form 4?

The filing states shares were sold to satisfy income tax liabilities resulting from the vesting of a restricted stock award for 200,000 shares.

How many ASPI shares did the reporting person own after the sale?

The reporting person beneficially owned 994,553 shares following the reported transaction.

What price range were the shares sold at?

The filing discloses the shares were sold in multiple transactions at prices ranging from $8.95 to $10.20.

Who signed the Form 4 and when?

The Form 4 was signed by Donald Ainscow, as attorney-in-fact, dated 09/03/2025.