ASPI interim CEO sells 22,500 shares at $13.599 under 10b5‑1

ASP Isotopes (ASPI) Form 4: Interim CEO and COO reported a sale of 22,500 shares of common stock on 10/14/2025 at a weighted average price of $13.599.

Rhea-AI Filing Summary

ASP Isotopes (ASPI) Form 4: Interim CEO and COO reported a sale of 22,500 shares of common stock on 10/14/2025 at a weighted average price of $13.599. The filing states these were “sell to cover” transactions executed under a Rule 10b5‑1 trading plan adopted on June 9, 2025 to cover tax withholding tied to vesting of restricted stock awards.

Trades occurred across multiple executions at prices ranging from $12.31 to $14.46. Following the transactions, the reporting person beneficially owns 1,647,193 shares directly.

Insider Trade Summary

Net Seller: 22,500 shares

Net Sell 1 txn

Insider Ainscow Robert

Role Interim CEO and COO

Sold 22,500 shs ($306K)

Type	Security	Shares	Price	Value
Sale	Common Stock	22,500	$13.599	$306K

Holdings After Transaction: Common Stock — 1,647,193 shares (Direct)

Footnotes (2)

1. F1. Represents "sell to cover" sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on June 9, 2025 to cover tax withholding obligations in connection with the vesting of restricted stock awards.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $12.31 to $14.46, 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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did ASPI report?

The Interim CEO and COO sold 22,500 shares of common stock on 10/14/2025.

What was the price of the ASPI share sale?

The weighted average price was $13.599, with trades from $12.31 to $14.46.

Why were the ASPI shares sold?

The filing states the sales were “sell to cover” to satisfy tax withholding from vesting of restricted stock awards under a Rule 10b5‑1 plan.

When was the trading plan adopted?

The Rule 10b5‑1 trading plan was adopted on June 9, 2025.

How many ASPI shares does the insider own after the sale?

The reporting person beneficially owns 1,647,193 shares directly after the transactions.

What is the insider’s role at ASPI?

The reporting person is Interim CEO and COO of ASP Isotopes Inc.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 10/16/2025 - 12:00 AM Learn about SEC filing dates

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
Estimated average burden
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).

X

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^*

Ainscow Robert

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Interim CEO and COO

3. Date of Earliest Transaction (Month/Day/Year)
10/14/2025

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	10/14/2025		S(1)		22,500	D	$13.599(2)	1,647,193	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. Represents "sell to cover" sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on June 9, 2025 to cover tax withholding obligations in connection with the vesting of restricted stock awards.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $12.31 to $14.46, 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	10/16/2025
	** 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.