ASP Isotopes (ASPI) COO sells shares under 10b5-1 plan for tax withholding

Rhea-AI Filing Summary

ASP Isotopes Inc. COO Robert Ainscow reported selling 8,438 shares of common stock in open-market transactions at a weighted average price of $6.999 per share. According to the disclosure, these "sell to cover" trades were made under a Rule 10b5-1 trading plan adopted on June 9, 2025 to cover tax withholding obligations tied to vesting restricted stock awards, rather than discretionary sales. Following the transactions, Ainscow directly holds 2,281,879 ASP Isotopes shares.

Insider Trade Summary 10b5-1

Net Seller: 8,438 shares ($59,058)

Net Sell 1 txn

Insider Ainscow Robert

Role COO

Sold 8,438 shs ($59K)

Type	Security	Shares	Price	Value
Sale	Common Stock	8,438	$6.999	$59K

Holdings After Transaction: Common Stock — 2,281,879 shares (Direct, null)

Footnotes (1)

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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.785 to $7.265, 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: 8,438 shares Weighted average sale price: $6.999 per share Post-transaction holdings: 2,281,879 shares +2 more

5 metrics

Shares sold 8,438 shares Open-market sale to cover tax withholding

Weighted average sale price $6.999 per share Open-market transactions in common stock

Post-transaction holdings 2,281,879 shares Common stock held directly after sale

Price range of sales $6.785–$7.265 per share Multiple transactions within this range

Net shares sold 8,438 shares Net-sell direction in transaction summary

Key Terms

Rule 10b5-1 trading plan, sell to cover, tax withholding obligations, restricted stock awards, +1 more

5 terms

Rule 10b5-1 trading plan regulatory

"sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on June 9, 2025"

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.

sell to cover financial

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

Sell to cover is when a person who receives company stock through options or awards sells just enough shares immediately to pay required taxes, exercise costs, or fees, keeping the rest. Think of it like cashing part of a bonus to cover the tax bill so you can keep the remainder. For investors, it can create predictable small selling pressure and slightly change the number of shares actually held by insiders without increasing long‑term dilution.

tax withholding obligations financial

"to cover tax withholding obligations in connection with the vesting of restricted stock awards"

restricted stock awards financial

"tax withholding obligations in connection with the vesting of restricted stock awards"

Restricted stock awards are company shares given to employees or executives that cannot be sold or transferred until certain conditions — like staying with the company for a set time or meeting performance targets — are met, like a gift that is locked in a safe until rules are satisfied. Investors care because these awards tie management’s pay to company performance, can increase the number of shares outstanding when they become tradable (dilution), and may signal expected future selling pressure or commitment to long-term growth.

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.

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Form 4 Insider Transactions: What Each Field Means →

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)
06/08/2026

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	06/08/2026		S(1)		8,438	D	$6.999(2)	2,281,879	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 "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 $6.785 to $7.265, 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	06/10/2026
	** 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)

FAQ

What insider transaction did ASP Isotopes (ASPI) report for COO Robert Ainscow?

ASP Isotopes reported that COO Robert Ainscow sold 8,438 shares of common stock. The sales were open-market transactions used to cover tax withholding obligations from vesting restricted stock awards, rather than a discretionary reduction of his ownership stake.

At what price did ASP Isotopes (ASPI) COO Robert Ainscow sell his shares?

The Form 4 shows a weighted average sale price of $6.999 per share. A footnote explains the shares were sold in multiple trades at prices ranging from $6.785 to $7.265, with full trade details available on request.

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

After the reported sales, COO Robert Ainscow directly holds 2,281,879 shares of ASP Isotopes common stock. This indicates the 8,438 shares sold to cover tax withholding represent a relatively small portion of his overall direct ownership.

Was the ASP Isotopes (ASPI) insider sale part of a Rule 10b5-1 trading plan?

Yes. The filing states the sales were effected under a Rule 10b5-1 trading plan adopted on June 9, 2025. Such plans prearrange trades, making their timing more routine and less indicative of short-term views on the stock.

Why did ASP Isotopes (ASPI) COO Robert Ainscow sell shares in this Form 4 filing?

The Form 4 footnote explains the sales were "sell to cover" transactions. They were executed to satisfy tax withholding obligations arising from the vesting of restricted stock awards, rather than to realize gains or significantly change his investment position.