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  4. [Form 4] ASP Isotopes Inc. Insider Trading Activity

ASP Isotopes CEO sells 251K shares to cover taxes

Filing Impact
(Moderate)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

ASP Isotopes Inc. (ASPI) reported that Chairman and CEO Paul Elliot Mann sold a total of 251,275 shares of common stock in three transactions, all described as sell-to-cover sales effected under a Rule 10b5-1 trading plan adopted on December 30, 2025 to cover tax withholding obligations on quarterly vesting of a restricted stock award.

The reported weighted average prices were $3.91 for 83,758 shares (range $3.75–$3.96), $3.92 for 83,758 shares (range $3.875–$3.98), and $4.10 for 83,759 shares (range $3.925–$4.26). Post-transaction share holdings are not stated in this data.

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Insider Mann Paul Elliot
Role Chairman and CEO
Sold 251,275 shs ($999K)
Type Security Shares Price Value
Sale Common Stock F1, F2 83,758 $3.91 $327K
Sale Common Stock F1, F3 83,758 $3.92 $328K
Sale Common Stock F1, F4 83,759 $4.10 $343K
Holdings After Transaction: Common Stock — 9,328,570 shares (Direct)
Footnotes (4)
  1. F1. Represents "sell to cover" sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 30, 2025 to cover tax withholding obligations in connection with the quarterly vesting of a restricted stock award.
  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 this footnote.
  3. F3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.875 to $3.98, 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.
  4. F4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.925 to $4.26, 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.
Shares sold (total) 251,275 shares Total common shares sold by the CEO across three transactions
First transaction 83,758 shares at $3.91 per share Weighted average price; trades ranged from $3.75 to $3.96
Second transaction 83,758 shares at $3.92 per share Weighted average price; trades ranged from $3.875 to $3.98
Third transaction 83,759 shares at $4.10 per share Weighted average price; trades ranged from $3.925 to $4.26
Rule 10b5-1 plan adoption date December 30, 2025 Date the trading plan covering these sell-to-cover sales was adopted
Rule 10b5-1 trading plan regulatory
"sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person"
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.
restricted stock award financial
"tax withholding obligations in connection with the quarterly vesting of a restricted stock award"
A restricted stock award is company shares given to an employee or executive that cannot be sold or fully owned until certain conditions—like staying with the company for a set time or hitting performance targets—are met. Think of it as a gift that only becomes yours after you fulfill specific obligations; for investors, these awards matter because they can increase the total shares outstanding when they vest, reveal how management is being paid and motivated, and create potential selling pressure when restrictions lift.
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.
tax withholding obligations financial
"to cover tax withholding obligations in connection with the quarterly vesting"

FAQ

What insider activity did ASPI disclose in this Form 4?
ASPI disclosed that its Chairman and CEO, Paul Elliot Mann, sold 251,275 shares of common stock in three transactions, reported as sell-to-cover sales to satisfy tax withholding obligations tied to a vesting restricted stock award.

How many ASPI shares did the CEO sell and at what reported prices?
The CEO sold 251,275 shares in total: 83,758 shares at a weighted average $3.91, 83,758 shares at $3.92, and 83,759 shares at $4.10. Each price is a weighted average over multiple trades within the price ranges disclosed.

Were the ASPI insider sales made under a Rule 10b5-1 trading plan?
Yes. The sales are described as effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 30, 2025, specifically to cover tax withholding obligations from quarterly vesting of a restricted stock award.

What does sell-to-cover mean in the context of this ASPI Form 4?
Sell-to-cover means the insider sold shares of ASPI common stock primarily to cover tax withholding obligations arising from the vesting of a restricted stock award, rather than as a discretionary sale of investment holdings.

What price ranges were reported for the ASPI insider sales?
The filing states that trades occurred in ranges of $3.75–$3.96, $3.875–$3.98, and $3.925–$4.26 per share, with the reported per-share prices being weighted averages of the multiple transactions within each range.

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SEC Form 4
FORM 4UNITED 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.
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)
XDirector10% Owner
XOfficer (give title below)Other (specify below)
Chairman and CEO
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
09/02/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock09/02/2026S(1)83,758D$3.91(2)9,496,087D
Common Stock09/03/2026S(1)83,758D$3.92(3)9,412,329D
Common Stock09/04/2026S(1)83,759D$4.1(4)9,328,570D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount 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 December 30, 2025 to cover tax withholding obligations in connection with the quarterly vesting of a restricted stock award.
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 this footnote.
3. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.875 to $3.98, 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.
4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.925 to $4.26, 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, as attorney-in-fact09/04/2026
** Signature of Reporting PersonDate
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)

Source: View Original Filing on SEC EDGAR