ASP Isotopes (ASPI) COO Ainscow sells 8,438 shares under Rule 10b5-1 plan

Rhea-AI Filing Summary

ASP Isotopes Inc. COO Robert Ainscow reported an open-market sale of 8,438 shares of common stock. The transaction occurred on March 6, 2026 at a weighted average price of $5.439 per share.

The sale was a "sell to cover" under a Rule 10b5-1 trading plan adopted on June 9, 2025 to cover tax withholding obligations from vesting restricted stock awards. After this transaction, Ainscow directly owns 1,537,817 ASP Isotopes common shares.

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^*

Ainscow Robert

(Last) (First) (Middle)

C/O ASP ISOTOPES INC.

2200 ROSS AVENUE, SUITE 4575E

(Street)

DALLAS TX 75201

(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)
	COO

3. Date of Earliest Transaction (Month/Day/Year)
03/06/2026

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	03/06/2026		S(1)		8,438	D	$5.439(2)	1,537,817	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 $5.00 to $5.65, 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	03/06/2026
	** 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) COO Robert Ainscow report?

Robert Ainscow reported selling 8,438 shares of ASP Isotopes common stock. The Form 4 shows an open-market sale on March 6, 2026 at a weighted average price of $5.439 per share to cover tax withholding on vested restricted stock awards.

How many ASP Isotopes (ASPI) shares did Robert Ainscow sell and at what price?

He sold 8,438 shares of ASP Isotopes common stock. The filing lists a weighted average sale price of $5.439 per share, with individual trades executed between $5.00 and $5.65, as disclosed in the weighted-average pricing footnote.

Why did Robert Ainscow sell ASP Isotopes (ASPI) shares on March 6, 2026?

The sale was to cover tax withholding obligations tied to vesting restricted stock awards. Footnotes state it was a "sell to cover" transaction executed under a Rule 10b5-1 trading plan adopted on June 9, 2025 by the filing person.

How many ASP Isotopes (ASPI) shares does Robert Ainscow hold after this Form 4 transaction?

After the transaction, Robert Ainscow directly holds 1,537,817 shares of ASP Isotopes common stock. This post-transaction ownership figure is reported in the Form 4 as the total number of shares beneficially owned following the sale.

Was Robert Ainscow’s ASP Isotopes (ASPI) share sale under a Rule 10b5-1 plan?

Yes. A footnote explains the transaction was effected under a Rule 10b5-1 trading plan adopted on June 9, 2025. The sale was characterized as a "sell to cover" for satisfying tax withholding on vesting restricted stock awards.

What price range applied to Robert Ainscow’s recent ASP Isotopes (ASPI) share sale?

The weighted average sale price reported was $5.439 per share. A footnote states the shares were sold in multiple transactions at prices ranging from $5.00 to $5.65, and detailed trade breakdowns are available upon request.