ASPI

SEC source: 0001477932-26-005430 · form4.xml · nonDerivative · entry 3

Mann Paul Elliot · CIK 0001744816 · Director · Chairman and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,328,570

F1 · kind: 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.

F4 · price: 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.

SEC source: 0001477932-26-005430 · form4.xml · nonDerivative · entry 2

Mann Paul Elliot · CIK 0001744816 · Director · Chairman and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,412,329

F1 · kind: 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.

F3 · price: 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.

SEC source: 0001477932-26-005432 · form4.xml · nonDerivative · entry 1

Ainscow Donald George · CIK 0002079961 · EVP, Gen Counsel, Secretary

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 776,322

F1 · kind: 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.

F2 · price: 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.

SEC source: 0001477932-26-005431 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 2,256,879

F1 · kind: Represents sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 13, 2024.

F2 · price: 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.

SEC source: 0001477932-26-005430 · form4.xml · nonDerivative · entry 1

Mann Paul Elliot · CIK 0001744816 · Director · Chairman and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,496,087

F1 · kind: 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.

F2 · price: 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.

SEC source: 0001477932-26-004177 · form4.xml · nonDerivative · entry 1

Kiessling Heather · CIK 0002026548 · Chief Financial Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,526,252

F1 · kind: Represents "sell to cover" sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 19, 2025 to cover tax withholding obligations in connection with the quarterly vesting of a restricted stock award.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.13 to $6.52, 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.

SEC source: 0001477932-26-004156 · form4.xml · nonDerivative · entry 1

Gorley Michael · CIK 0002012446 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 87,908

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.10 to $6.63, 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.

SEC source: 0001477932-26-004157 · form4.xml · nonDerivative · entry 2

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 672,247

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.10 to $6.25, 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.

SEC source: 0001477932-26-004176 · form4.xml · nonDerivative · entry 1

Ainscow Donald George · CIK 0002079961 · EVP, Gen Counsel, Secretary

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 800,000

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.11 to $6.17, 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.

SEC source: 0001477932-26-004157 · form4.xml · nonDerivative · entry 1

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 722,247

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.21 to $6.31, 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.

SEC source: 0001477932-26-003753 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 2,281,879

F1 · kind: 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.

F2 · price: 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.

SEC source: 0001477932-26-003633 · form4.xml · nonDerivative · entry 4

Mann Paul Elliot · CIK 0001744816 · Director · Chairman and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,579,845

F2 · kind: 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.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.53 to $8.13, 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.

SEC source: 0001477932-26-003633 · form4.xml · nonDerivative · entry 3

Mann Paul Elliot · CIK 0001744816 · Director · Chairman and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,663,424

F2 · kind: 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.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.81 to $8.52, 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.

SEC source: 0001477932-26-003633 · form4.xml · nonDerivative · entry 2

Mann Paul Elliot · CIK 0001744816 · Director · Chairman and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,747,182

F2 · kind: 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.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.49 to $8.14, 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.

SEC source: 0001477932-26-003630 · form4.xml · nonDerivative · entry 1

Kiessling Heather · CIK 0002026548 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,549,376

F1 · date: This award of common stock shall vest (subject to compliance with applicable vesting conditions) in semi-annual installments over a four-year period beginning on the grant date.

F1 · price: This award of common stock shall vest (subject to compliance with applicable vesting conditions) in semi-annual installments over a four-year period beginning on the grant date.

SEC source: 0001477932-26-003633 · form4.xml · nonDerivative · entry 1

Mann Paul Elliot · CIK 0001744816 · Director · Chairman and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 9,830,940

F1 · date: This award of common stock was issued to the reporting person pursuant to his Employment Agreement dated October 4, 2021, as amended on December 20, 2022 and April 5, 2024, and shall vest (subject to compliance with applicable vesting conditions) in four equal installments over a one-year period beginning on March 1, 2026.

F1 · price: This award of common stock was issued to the reporting person pursuant to his Employment Agreement dated October 4, 2021, as amended on December 20, 2022 and April 5, 2024, and shall vest (subject to compliance with applicable vesting conditions) in four equal installments over a one-year period beginning on March 1, 2026.

SEC source: 0001477932-26-003632 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · Chief Operating Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,290,317

F1 · date: This award of common stock shall vest (subject to compliance with applicable vesting conditions) in semi-annual installments over a four-year period beginning on the grant date.

F1 · price: This award of common stock shall vest (subject to compliance with applicable vesting conditions) in semi-annual installments over a four-year period beginning on the grant date.

SEC source: 0001477932-26-003631 · form4.xml · nonDerivative · entry 1

Ainscow Donald George · CIK 0002079961 · EVP, Gen Counsel, Secretary

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 900,000

F1 · date: This award of common stock shall vest (subject to compliance with applicable vesting conditions) in semi-annual installments over a four-year period beginning on the grant date.

F1 · price: This award of common stock shall vest (subject to compliance with applicable vesting conditions) in semi-annual installments over a four-year period beginning on the grant date.

SEC source: 0001477932-26-002387 · form4.xml · nonDerivative · entry 3

Moore Duncan · CIK 0001888265 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,044,928

F3 · kind: The sale of shares reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 31, 2025 and includes an amount for the purpose of satisfying the reporting person's income tax liabilities resulting from the vesting of a previously granted restricted stock award pursuant to an issuer equity incentive plan.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.055 to $5.52, 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.

SEC source: 0001477932-26-002390 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,490,317

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.055 to $5.52, 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.

SEC source: 0001477932-26-002388 · form4.xml · nonDerivative · entry 1

Kiessling Heather · CIK 0002026548 · Chief Financial Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 709,376

F1 · kind: Represents "sell to cover" sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 19, 2025 to cover tax withholding obligations in connection with the vesting of restricted stock awards.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.12 to $5.71, 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.

SEC source: 0001477932-26-001231 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,537,817

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.00 to $5.65, 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.

SEC source: 0001477932-26-002188 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,512,817

F1 · kind: Represents sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 13, 2024.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $4.42 to $4.58, 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.

SEC source: 0001477932-26-001127 · form4.xml · nonDerivative · entry 1

Mann Paul Elliot · CIK 0001744816 · Executive Chairman

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 7,597,385

F1 · kind: 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 quarterly vesting of a restricted stock award.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.10 to $5.57, 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.

SEC source: 0001477932-25-009164 · form4.xml · nonDerivative · entry 1

Gorley Michael · CIK 0002012446 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 117,908

F1 · price: Annual award of shares of restricted stock in connection with the reporting person's service as an independent director of ASP Isotopes Inc

SEC source: 0001477932-25-009169 · form4.xml · nonDerivative · entry 1

Ryan Robert John Andrew · CIK 0002011790 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 652,222

F1 · price: Annual award of shares of restricted stock in connection with the reporting person's service as an independent director of ASP Isotopes Inc.

SEC source: 0001477932-25-009171 · form4.xml · nonDerivative · entry 1

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 772,247

F1 · price: Annual award of shares of restricted stock in connection with the reporting person's service as an independent director of ASP Isotopes Inc.

SEC source: 0001477932-25-009167 · form4.xml · nonDerivative · entry 1

Hunter Ralph L. JR · CIK 0002088585 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 47,018

F1 · price: Annual award of shares of restricted stock in connection with the reporting person's service as an independent director of ASP Isotopes Inc.

SEC source: 0001477932-25-009230 · form4.xml · nonDerivative · entry 1

Kiessling Heather · CIK 0002026548 · Chief Financial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 732,500

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.73 to $5.885, 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 1.

SEC source: 0001477932-26-002387 · form4.xml · nonDerivative · entry 2

Moore Duncan · CIK 0001888265 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,056,570

F2 · price: 2025 annual award of shares of restricted stock in connection with the reporting person's service as an independent director of ASP Isotopes Inc.

SEC source: 0001477932-25-008938 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · Interim CEO and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,546,255

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.03 to $6.525, 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.

SEC source: 0001477932-25-008769 · form4.xml · nonDerivative · entry 1

Mann Paul Elliot · CIK 0001744816 · Director · Executive Chairman

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 7,759,538

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.565 to $5.9565, 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.

SEC source: 0001477932-25-008681 · form4.xml · nonDerivative · entry 2

Mann Paul Elliot · CIK 0001744816 · Director · Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 7,921,691

F3 · kind: Represents sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 13, 2024.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.54 to $6.015, 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.

SEC source: 0001477932-25-008682 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · Interim CEO and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,554,693

F1 · kind: Represents sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 13, 2024.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.54 to $6.015, 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.

SEC source: 0001477932-25-008506 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · Interim CEO and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,579,693

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.215 to $7.85, 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.

SEC source: 0001477932-25-008681 · form4.xml · nonDerivative · entry 1

Mann Paul Elliot · CIK 0001744816 · Director · Executive Officer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 7,971,691

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.215 to $7.85, 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.

SEC source: 0001477932-25-008354 · form4.xml · nonDerivative · entry 1

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 735,699

F1 · price: Award of shares of restricted stock in connection with the reporting person's service as an independent director of ASP Isotopes Inc. on the QLE Structuring and Strategic Transactions Committee.

SEC source: 0001477932-26-002387 · form4.xml · nonDerivative · entry 1

Moore Duncan · CIK 0001888265 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,020,022

F1 · price: Award of shares of restricted stock in connection with the reporting person's service as an independent director of ASP Isotopes Inc. on the QLE Structuring and Strategic Transactions Committee.

SEC source: 0001477932-25-007626 · form4.xml · nonDerivative · entry 1

Ainscow Robert · CIK 0001951275 · Interim CEO and COO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 1,647,193

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $12.31 to $14.46, 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.

SEC source: 0001477932-25-007322 · form4.xml · nonDerivative · entry 1

Gorley Michael · CIK 0002012446 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 81,360

F1 · kind: The sale of shares reported in this Form 4 includes an amount for the purpose of satisfying the reporting person's income tax liabilities resulting from the vesting of previously granted restricted stock awards pursuant to an issuer equity incentive plan.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.595 to $9.96, 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.

SEC source: 0001477932-25-007349 · form4.xml · nonDerivative · entry 3

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 710,230

F2 · kind: The sale of shares reported in this Form 4 includes an amount for the purpose of satisfying the reporting person's income tax liabilities resulting from the vesting of a previously granted restricted stock award and the exercise of a stock option issued pursuant to an issuer equity incentive plan.

F3 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.37 to $9.40, 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 3.

SEC source: 0001477932-25-007349 · form4.xml · derivative · entry 4

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 96,000 shares

Expires 2032-04-04

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_date: These options vested in a single installment 12 months after the grant date. The option was granted on April 4, 2022.

SEC source: 0001477932-25-007349 · form4.xml · nonDerivative · entry 2

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 784,338

F1 · kind: 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 a stock option.

SEC source: 0001477932-25-007349 · form4.xml · nonDerivative · entry 1

Wider Todd · CIK 0001642715 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 806,230

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001477932-25-006619 · form4.xml · derivative · entry 8

Mann Paul Elliot · CIK 0001744816 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 1,000,000 shares

Expires 2032-06-10

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · derivative.exercise_date: 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.

SEC source: 0001477932-25-006619 · form4.xml · derivative · entry 7

Mann Paul Elliot · CIK 0001744816 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 216,000 shares

Expires 2032-04-04

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: These options vested in a single installment 12 months after the grant date. The option was granted on April 4, 2022.

SEC source: 0001477932-25-006619 · form4.xml · nonDerivative · entry 6

Mann Paul Elliot · CIK 0001744816 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 8,084,191

F1 · kind: 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.

F4 · price: 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.

SEC source: 0001477932-25-006619 · form4.xml · nonDerivative · entry 5

Mann Paul Elliot · CIK 0001744816 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 8,165,268

F3 · kind: 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.

SEC source: 0001477932-25-006619 · form4.xml · nonDerivative · entry 4

Mann Paul Elliot · CIK 0001744816 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 8,399,734

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001477932-25-006619 · form4.xml · nonDerivative · entry 3

Mann Paul Elliot · CIK 0001744816 · Director · Chief Executive Officer · 10% owner

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 7,399,734

F3 · kind: 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.