ASP Isotopes (ASPI) chair sells 162,153 shares under Rule 10b5-1 plan

Rhea-AI Filing Summary

ASP Isotopes Inc. Executive Chairman Paul Elliot Mann reported an open-market sale of 162,153 shares of common stock at a weighted average price of $5.436 per share. According to the disclosure, these were “sell to cover” transactions under a Rule 10b5-1 trading plan to satisfy tax withholding on the quarterly vesting of a restricted stock award.

After these sales, Mann held 7,597,385 shares of ASP Isotopes common stock directly. The filing notes the shares were sold in multiple transactions at prices ranging from $5.10 to $5.57 per share.

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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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^*

Mann Paul Elliot

(Last) (First) (Middle)

C/O ASP ISOTOPES INC. 2200 ROSS AVENUE

SUITE 4575E

(Street)

DALLAS TX 75209

(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)
	Executive Chairman

3. Date of Earliest Transaction (Month/Day/Year)
03/02/2026

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	03/02/2026		S(1)		162,153	A	$5.436(2)	7,597,385	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 quarterly vesting of a restricted stock award.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.10 to $5.57, 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	03/02/2026
	** 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 insider transaction did ASP Isotopes (ASPI) report for Paul Elliot Mann?

ASP Isotopes reported that Executive Chairman Paul Elliot Mann sold 162,153 shares of common stock. The transaction was an open-market sale made under a Rule 10b5-1 trading plan to cover tax withholding tied to a restricted stock award’s quarterly vesting.

How many ASP Isotopes (ASPI) shares did Paul Elliot Mann sell and at what price?

Paul Elliot Mann sold 162,153 shares of ASP Isotopes common stock at a weighted average price of $5.436 per share. The filing adds that the shares were sold in multiple trades at prices between $5.10 and $5.57 per share.

Why did Paul Elliot Mann’s ASP Isotopes (ASPI) shares get sold in this Form 4 filing?

The shares were sold to cover tax withholding obligations related to the quarterly vesting of a restricted stock award. The filing states these were “sell to cover” sales executed under a Rule 10b5-1 trading plan adopted by the reporting person.

How many ASP Isotopes (ASPI) shares does Paul Elliot Mann hold after the reported sale?

After the reported transaction, Paul Elliot Mann directly owned 7,597,385 shares of ASP Isotopes common stock. This post-transaction holding figure is disclosed in the Form 4 as the total number of shares beneficially owned following the sale.

What price range did ASP Isotopes (ASPI) shares sell for in Paul Elliot Mann’s transaction?

The Form 4 notes that the shares were sold in multiple transactions at prices ranging from $5.10 to $5.57 per share. The reported price of $5.436 per share represents a weighted average across those individual trades.

What does the Rule 10b5-1 trading plan reference mean in the ASP Isotopes (ASPI) filing?

The filing explains that the sales were made pursuant to a Rule 10b5-1 trading plan adopted on June 9, 2025. It specifies that the plan’s sales were intended to cover tax withholding obligations from quarterly vesting of a restricted stock award.