ASP Isotopes COO sells 25K shares in plan trade

ASP Isotopes Inc. (ASPI) reported that its chief operating officer, Robert Ainscow, sold 25,000 shares of common stock in an open market or private transaction under a Rule 10b5-1 trading plan.

Rhea-AI Filing Summary

ASP Isotopes Inc. (ASPI) reported that its chief operating officer, Robert Ainscow, sold 25,000 shares of common stock in an open market or private transaction under a Rule 10b5-1 trading plan. The weighted average sale price was about $3.91 per share, and he now directly holds 2,256,879 shares.

Insider Trade Summary 10b5-1

Net Seller: 25,000 shares

Net Sell 1 txn

Insider Ainscow Robert

Role COO

Sold 25,000 shs ($98K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	25,000	$3.905	$98K

Holdings After Transaction: Common Stock — 2,256,879 shares (Direct)

Footnotes (2)

1. F1. Represents sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 13, 2024.
2. F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.75 to $3.96, 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.

Key Figures

Shares sold: 25,000 shares Weighted average sale price: $3.905 per share Sale price range: $3.75–$3.96 per share +2 more

5 metrics

Shares sold 25,000 shares Common stock disposition reported by the COO

Weighted average sale price $3.905 per share Average price across multiple sale transactions

Sale price range $3.75–$3.96 per share Range of prices for the multiple sale transactions

Shares held after transaction 2,256,879 shares Direct common stock holdings of the COO after the sale

Rule 10b5-1 plan adoption date December 13, 2024 Date the COO adopted the trading plan used for these sales

Key Terms

Rule 10b5-1 trading plan, weighted average price, open market or private transaction

3 terms

Rule 10b5-1 trading plan regulatory

"Represents sales effected pursuant to a Rule 10b5-1 trading plan adopted"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

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.

open market or private transaction financial

"Sale in open market or private transaction"

FAQ

What insider transaction did ASPI report for COO Robert Ainscow?

ASP Isotopes reported that COO Robert Ainscow sold 25,000 shares of common stock in a reported open market or private transaction, pursuant to an established trading plan, while retaining a substantial direct holding afterward.

At what price did the ASPI shares sell in this Form 4 transaction?

The filing reports a weighted average price of $3.905 per share. Ainscow’s shares were sold in multiple transactions at prices ranging from $3.75 to $3.96 per share, inclusive.

How many ASPI shares does the COO own after this sale?

After the reported sale, COO Robert Ainscow directly holds 2,256,879 shares of ASP Isotopes common stock, according to the Form 4 data.

Was the ASPI COO’s sale under a Rule 10b5-1 trading plan?

Yes. The sale was effected under a Rule 10b5-1 trading plan that the filing states was adopted by the reporting person on December 13, 2024, and the filing affirms Rule 10b5-1 status.

How many ASPI shares in total were sold in this Form 4 filing?

The filing covers a single reported transaction in which 25,000 shares of ASP Isotopes common stock were sold by the COO, based on the transaction summary information.

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Available on EDGAR 09/04/2026 - 09:32 PM Accepted by SEC EDGAR 09/04/2026 - 09:32 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).

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 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)
	COO

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)		25,000	D	$3.905(2)	2,256,879	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 sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 13, 2024.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.75 to $3.96, 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.

	/s/ Donald Ainscow, as attorney-in-fact	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)