[Form 4] ASP Isotopes Inc. Insider Trading Activity

Rhea-AI Filing Summary

Insider transactions by Paul Elliot Mann, CEO, director and 10% owner of ASP Isotopes Inc. (ASPI). The Form 4 reports multiple transactions on September 8-9, 2025. The filing shows sales totaling 447,263 shares disposed through Rule 10b5-1 "sell to cover" and net-share settlements at weighted-average prices reported around $8.14–$8.58. The reporting person also acquired or was issued stock/derivative awards: 216,000 and 1,000,000 employee stock options (exercise price $2) reported as acquired on 09/09/2025. Following these transactions, the reporting person beneficially owned 8,084,191 shares (direct).

The filing discloses that some dispositions were effected under a 10b5-1 trading plan adopted June 9, 2025 to cover tax withholding for vesting restricted stock and that other share withholdings satisfied option exercise obligations. No additional financial results or forward-looking statements are included.

Positive

• Insider used a Rule 10b5-1 trading plan adopted June 9, 2025 to execute planned sales, indicating pre-arranged compliance with insider-trading rules
• Acquisition of employee stock options: 216,000 and 1,000,000 options with $2 exercise price reported, showing continued compensation alignment

Negative

• Significant share dispositions: 447,263 shares were disposed (sell-to-cover and net-share settlements) on September 8-9, 2025
• Weighted-average sale prices for reported sales were in the range $8.135–$8.575, indicating insider liquidity events that increased tradable supply

Insights

Corporate Governance Expert

TL;DR: Insider followed formal trading plan and used net settlement to satisfy tax/exercise obligations; activity is compliance-focused, not opportunistic.

The report documents structured dispositions under a Rule 10b5-1 plan adopted June 9, 2025 and share withholdings to satisfy option exercise or tax obligations. Use of a 10b5-1 plan is a governance best practice to mitigate insider trading concerns because it provides pre-specified execution terms. The mix of option grants/awards and share disposals is consistent with compensation-related liquidity events rather than open-market opportunistic selling. Materiality to shareholders is moderate given the size of beneficial ownership remaining (8,084,191 shares direct) and the absence of extraordinary transfers or pledges.

Securities Analyst

TL;DR: Significant option activity and share movements; transactions affect outstanding insider-held shares but do not disclose company operating metrics.

The filing shows acquisition of employee stock options totaling 1,216,000 options (two tranches exercisable with stated vesting/expiration dates) and contemporaneous dispositions totaling 447,263 common shares via sell-to-cover and net-settlement. These transactions change the insider's liquid share position yet leave substantial direct beneficial ownership. From a market-impact perspective, the disclosed sales were executed across price ranges noted as $8.135 to $8.575; the filing supplies a weighted-average sale price for some lots. No information on company performance or capital structure changes is provided, limiting further valuation implications.

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^*

Mann Paul Elliot

(Last) (First) (Middle)

C/O ASP ISOTOPES INC.

601 PENNSYLVANIA AVENUE NW, SUITE 900

(Street)

WASHINGTON DC 20004

(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)

X	Director	X	10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Executive Officer

3. Date of Earliest Transaction (Month/Day/Year)
09/08/2025

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	09/08/2025		S(1)		81,076	D	$8.5279(2)	7,234,378	D
Common Stock	09/09/2025		M		216,000	A	$2	7,450,378	D
Common Stock	09/09/2025		F(3)		50,644	D	$8.53	7,399,734	D
Common Stock	09/09/2025		M		1,000,000	A	$2	8,399,734	D
Common Stock	09/09/2025		F(3)		234,466	D	$8.53	8,165,268	D
Common Stock	09/09/2025		S(1)		81,077	D	$8.3886(4)	8,084,191	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
Employee Stock Option (right to buy)	$2	09/09/2025		M			216,000	04/04/2023(5)	04/04/2032	Common Stock	216,000	$0	0	D
Employee Stock Option (right to buy)	$2	09/09/2025		M			1,000,000	06/10/2025(6)	06/10/2032	Common Stock	1,000,000	$0	0	D

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 $8.135 to $8.575, 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 Footnote 2.

3. Represents shares withheld by the Company in connection with net share settlement to satisfy the exercise price associated with the reporting person's exercise of employee stock options. No shares were sold by the reporting person to satisfy the exercise price or any tax liability.

4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.135 to $8.575, 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 Footnote 2.

5. These options vested in a single installment 12 months after the grant date. The option was granted on April 4, 2022.

6. These options vested in thirty-six equal installments beginning on the last day of month after the option's grant date. The option was granted on June 10, 2022.

Remarks:

	/s/ Donald Ainscow, as attorney-in-fact	09/10/2025
	** 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 transactions did ASPI CEO Paul Elliot Mann report on Form 4?

The Form 4 shows dispositions totaling 447,263 common shares on September 8-9, 2025 and acquisitions related to employee stock options of 216,000 and 1,000,000 options (exercise price $2).

Were the sales by the reporting person part of a 10b5-1 trading plan?

Yes. The filing states sales represented "sell to cover" transactions effected pursuant to a Rule 10b5-1 trading plan adopted June 9, 2025 to cover tax withholding on vesting awards.

How many shares does the reporting person beneficially own after these transactions?

Following the reported transactions the filing discloses beneficial ownership of 8,084,191 shares (direct).

What were the reported price ranges for the disposed shares?

The filing reports sales at weighted-average prices and states the shares were sold at prices ranging from $8.135 to $8.575 for the indicated lots.

Did the filing report any shares withheld to satisfy option exercises?

Yes. The filing states certain shares (e.g., 50,644 and 234,466) were withheld by the company in connection with net-share settlement to satisfy the exercise price associated with option exercises.

Does the Form 4 include any company earnings or forward-looking statements?

No. The Form 4 only discloses changes in beneficial ownership and related explanations; it does not contain earnings data or forward-looking operational information.