ASP Isotopes EVP sells 23,678 shares for taxes

ASP Isotopes Inc. (ASPI) reported that executive officer Donald George Ainscow, EVP, General Counsel and Secretary, had 23,678 shares of common stock sold to cover tax obligations arising from an equity award.

Rhea-AI Filing Summary

ASP Isotopes Inc. (ASPI) reported that executive officer Donald George Ainscow, EVP, General Counsel and Secretary, had 23,678 shares of common stock sold to cover tax obligations arising from an equity award. The company executed these shares under a mandatory sell-to-cover provision and stated the sale was not a discretionary trade by Ainscow. After these sales, he holds 776,322 shares of common stock directly.

Insider Trade Summary

Net Seller: 23,678 shares

Net Sell 1 txn

Insider Ainscow Donald George

Role EVP, Gen Counsel, Secretary

Sold 23,678 shs ($92K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	23,678	$3.89	$92K

Holdings After Transaction: Common Stock — 776,322 shares (Direct)

Footnotes (2)

1. F1. Represents shares automatically sold by ASP Isotopes Inc. (the "Company") on behalf of the reporting person pursuant to a mandatory sell-to-cover provision in the award agreement required to cover minimum statutory tax withholding obligations. The sale does not represent a discretionary trade by the reporting person.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.885 to $3.9202, inclusive. The reporting person undertakes to provide 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 this footnote.

Key Figures

Shares sold: 23,678 shares Weighted average sale price: $3.89 per share Sale price range: $3.885 to $3.9202 per share +1 more

4 metrics

Shares sold 23,678 shares Common stock sold to cover minimum statutory tax withholding obligations

Weighted average sale price $3.89 per share Weighted average price for the sell-to-cover transactions

Sale price range $3.885 to $3.9202 per share Range of individual transaction prices included in the weighted average

Shares held after transaction 776,322 shares Direct common stock ownership by Donald George Ainscow following the sale

Key Terms

sell-to-cover, minimum statutory tax withholding obligations, weighted average price

3 terms

sell-to-cover financial

"pursuant to a mandatory sell-to-cover provision in the award agreement"

Sell-to-cover is when part of newly issued or exercised company stock is immediately sold to pay required taxes and fees, so the recipient keeps the remaining shares. For investors this matters because it reduces the number of shares insiders or employees actually hold after a grant, can create small, routine share sales that aren’t signal of cashing out, and slightly increases share supply on the market—like selling a portion of a paycheck to cover the tax bill.

minimum statutory tax withholding obligations financial

"required to cover minimum statutory tax withholding obligations"

weighted average price financial

"The price reported in Column 4 is a weighted average price"

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

FAQ

What insider transaction did ASPI disclose in this Form 4?

ASP Isotopes disclosed that EVP, General Counsel and Secretary Donald George Ainscow had 23,678 shares of common stock sold, executed by the company under a mandatory sell-to-cover provision to satisfy minimum statutory tax withholding obligations on an equity award.

Was the ASPI insider stock sale a discretionary trade by the executive?

No. The filing states the shares were sold by the company under a mandatory sell-to-cover provision to cover minimum statutory tax withholding. It explicitly notes that the sale does not represent a discretionary trade by Donald George Ainscow.

How many ASPI shares does the reporting person hold after this transaction?

After the tax-related sale, Donald George Ainscow directly holds 776,322 shares of ASP Isotopes Inc. common stock, according to the post-transaction ownership figure reported in the Form 4.

At what price were the ASPI shares sold in this sell-to-cover transaction?

The reported price is a weighted average of $3.89 per share. The filing notes sales occurred in multiple transactions at prices ranging from $3.885 to $3.9202 per share, inclusive.

Was a Rule 10b5-1 trading plan involved in this ASPI Form 4 transaction?

No. The filing’s Rule 10b5-1 checkbox is not marked as being pursuant to a plan, and the footnote describes the sale as under a mandatory sell-to-cover provision for tax withholding, not a discretionary plan trade.

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Available on EDGAR 09/04/2026 - 09:33 PM Accepted by SEC EDGAR 09/04/2026 - 09:33 PM 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).

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 Donald George

(Last) (First) (Middle)

C/O ASP ISOTOPES INC.

2200 ROSS AVENUE, SUITE 4575E

(Street)

DALLAS TEXAS 75201

(City) (State) (Zip)

UNITED STATES

(Country)

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)
	EVP, Gen Counsel, Secretary

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/02/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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	09/02/2026		S(1)		23,678	D	$3.89(2)	776,322	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 shares automatically sold by ASP Isotopes Inc. (the "Company") on behalf of the reporting person pursuant to a mandatory sell-to-cover provision in the award agreement required to cover minimum statutory tax withholding obligations. The sale does not represent a discretionary trade by the reporting person.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.885 to $3.9202, inclusive. The reporting person undertakes to provide 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 this footnote.

	/s/ Donald Ainscow	09/04/2026
	** 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.
* Form 4: SEC 1474 (03-26)