Low Russell

SEC source: 0001689237-26-000014 · form4-05202026_050503.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 154,900

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 16, 2026 of service vesting restricted stock units granted to the executive in May 2022. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F3 · balance_after: Of the shares held after this vesting event on May 16, 2026, 106,691 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000012 · form4-05192026_050501.xml · nonDerivative · entry 5

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 155,611

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F10 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2026 of service vesting restricted stock units granted to the executive in May 2023. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F11 · balance_after: Of the shares held after this vesting event on May 15, 2026, 108,161 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000012 · form4-05192026_050501.xml · nonDerivative · entry 4

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 157,064

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F8 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2026 of service vesting restricted stock units granted to the executive in May 2024. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F9 · balance_after: Of the shares held after this vesting event on May 15, 2026, 111,166 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000012 · form4-05192026_050501.xml · nonDerivative · entry 3

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 158,786

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F5 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2026 of service vesting restricted stock units granted to the executive in May 2025. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F7 · balance_after: Of the shares held after this vesting event on May 15, 2026, 114,727 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000012 · form4-05192026_050501.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 162,502

F3 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2026. In this grant, the executive may earn shares of common stock, ranging from zero to 200% of the granted units. The shares are earned based on the achievement of performance goals based on relative total shareholder return over a performance period of January 1, 2026 to December 31, 2028. Assuming continuation of employment, 100% of the earned shares will vest on measurement of performance in 2029. Unearned restricted stock units will forfeit at such time.

F4 · balance_after: Of the shares held after this grant on May 15, 2026, 122,412 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000012 · form4-05192026_050501.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 143,036

F1 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2026. Assuming continuation of employment, these restricted stock units will vest as to one-third of the shares granted on each of May 15, 2027, May 15, 2028, and May 15, 2029.

F2 · balance_after: Of the shares held following this grant on May 15, 2026, 102,946 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000010 · form4-05072026_050501.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 123,570

F1 · kind: This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 11, 2025.

F2 · balance_after: Of the shares held after this sale on May 6, 2026, 83,480 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000008 · form4-05042026_050501.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 131,038

F1 · kind: This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 11, 2025.

F2 · balance_after: Of the shares held after this sale on May 1, 2026, 83,480 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000006 · form4-04022026_050404.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 132,282

F1 · kind: This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 11, 2025.

F2 · balance_after: Of the shares held after this sale on April 1, 2026, 83,480 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001689237-26-000004 · form4-03262026_050303.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 133,526

F1 · kind: This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on December 11, 2025.

F2 · balance_after: Of the shares held after this sale on March 24, 2026, 83,480 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture. This amount includes restricted stock units earned by the reporting person upon the achievement of 112.5% of the restricted stock units granted in 2025 based upon the achievement of 2025 performance goals.

SEC source: 0001689237-26-000002 · form4-03032026_050301.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 130,928

F2 · price: Represents the closing price of the Company's common stock on March 2, 2026, the date of the tax withholding.

F1 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on February 28, 2026 of performance-based restricted stock units ("2024 PRSUs") granted to the executive in May 2024. Of the 2024 PRSUs granted, 150% were determined to be earned by the executive pursuant to a resolution of the Axcelis Technologies, Inc. Compensation Committee on February 13, 2025, with half of the earned shares vesting on February 28, 2025 and the remaining half of the earned shares vesting on February 28, 2026. The shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested 2024 PRSUs.

F3 · balance_after: Of the shares held after the vesting of the remaining 2024 PRSUs, 79,638 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-013804 · form4-05202025_040501.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 136,155

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F4 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 17, 2025 of service-vesting restricted stock units ("RSUs") granted to the executive in May 2021. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested RSUs.

F5 · balance_after: Of the shares held after this vest event on May 17, 2025,90,321 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-013804 · form4-05202025_040501.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 137,142

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 16, 2025 of service vesting restricted stock units granted to the executive in May 2022. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F3 · balance_after: Of the shares held after this vesting event on May 16, 2025, 92,361 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-013644 · form4-05192025_040520.xml · nonDerivative · entry 4

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 137,854

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F8 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2025 of service vesting restricted stock units granted to the executive in May 2023. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F9 · balance_after: Of the shares held after this vesting event on May 15, 2025, 93,832 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-013644 · form4-05192025_040520.xml · nonDerivative · entry 3

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 139,307

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F5 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2025 of service vesting restricted stock units granted to the executive in May 2024. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F7 · balance_after: Of the shares held after this vesting event on May 15, 2025, 96,836 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-013644 · form4-05192025_040520.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 141,029

F3 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2025. In this grant, the executive may earn shares of common stock, ranging from zero to 150% of the granted units. The shares are earned based on the achievement of 2025 performance goals. Assuming continuation of employment, 50% of the earned shares will vest on February 28, 2027, and 50% of the earned shares will vest on February 28, 2028. Unearned restricted stock units will forfeit on February 28, 2026.

F4 · balance_after: Of the shares held after this grant on May 15, 2025, 100,397 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-013644 · form4-05192025_040520.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 110,291

F1 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2025. Assuming continuation of employment, these restricted stock units will vest as to 25% of the shares granted on each of May 15, 2026, May 15, 2027, May 15, 2028, and May 15, 2029.

F2 · balance_after: Of the shares held following this grant on May 15, 2025, 69,659 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-006548 · form4-03042025_040323.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 79,553

F4 · kind: This forfeiture of shares for tax withholding purposes relates to the vesting on February 28, 2025 of performance based restricted stock units ("2024 PRSUs") granted to the executive in May 2024. Of the 2024 PRSUs granted, 150% were determined to be earned by the executive pursuant to a resolution of the Axcelis Technologies, Inc. Compensation Committee on February 13, 2025, and half of the earned shares vested on February 28, 2025. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested 2024 PRSUs.

F2 · price: Represents the closing price of the Company's common stock on February 28, 2025, the date of the tax withholding.

F5 · balance_after: Of the shares held as of February 28, 2025 after the vesting of the 2024 PRSUs, 38,921 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-25-006548 · form4-03042025_040323.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 84,765

F1 · kind: This forfeiture of shares for tax withholding purposes relates to the vesting on February 28, 2025 of performance based restricted stock units ("2023 PRSUs") granted to the executive in May 2023. The units vesting on the 2023 PRSUs were deemed earned by the Compensation Committee in February 2024, and the shares vesting on February 28, 2025 represent the final tranche of that grant. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested 2023 PRSUs.

F2 · price: Represents the closing price of the Company's common stock on February 28, 2025, the date of the tax withholding.

F3 · balance_after: Of the shares held as of February 28, 2025 after the vesting of the 2023 PRSUs, 49,604 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-015555 · form4-06052024_040604.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 81,566

F2 · price: Represents the closing price of the common stock on the date prior to the tax withholding.

F1 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting in May 2024 of 4 service vesting restricted stock units granted to the executive in May 2020, 2021, 2022 and 2023. As agreed with the executive, the shares issued to the executive on those vesting events were reduced by a number of shares to cover the executive's tax withholding obligation with respect to the vested restricted stock units. However, the number of shares withheld on the vesting dates was insufficient to cover a Massachusetts income tax surcharge applicable to the executive, so additional shares have been withheld to cover the shortfall, as reported herein.

F3 · balance_after: Of the shares held after this forfeiture event on June 5, 2024, 50,594 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-013740 · form4-05202024_040504.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 81,953

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 17, 2024 of service vesting restricted stock units granted to the executive in May 2021. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F3 · balance_after: Of the shares held after this vesting event on May 17, 2024, 50,594 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture

SEC source: 0001415889-24-013489 · form4-05172024_040536.xml · nonDerivative · entry 5

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 82,858

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F10 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 16, 2024 of service vesting restricted stock units granted to the executive in May 2022. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F11 · balance_after: Of the shares held after this vesting event on May 16, 2024, 52,634 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-013489 · form4-05172024_040536.xml · nonDerivative · entry 4

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 83,510

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F8 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2024 of service vesting restricted stock units granted to the executive in May 2020. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F9 · balance_after: f the shares held after this vesting event on May 15, 2024, 54,104 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-013489 · form4-05172024_040536.xml · nonDerivative · entry 3

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 84,843

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F5 · acquired: This forfeiture of shares for tax withholding purposes relates to the vesting on May 15, 2024 of service vesting restricted stock units granted to the executive in May 2023. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested restricted stock units.

F7 · balance_after: Of the shares held after this vesting event on May 15, 2024, 57,109 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-013489 · form4-05172024_040536.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 86,242

F3 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2024. In this grant, the executive may earn shares of common stock, ranging from zero to 150% of the granted units. The shares are earned based on the achievement of 2024 performance goals. Assuming continuation of employment, 50% of the earned shares will vest on February 28, 2025, and 50% of the earned shares will vest on February 28, 2026. Unearned restricted stock units will forfeit on February 28, 2025.

F4 · balance_after: Of the shares held after this grant on May 15, 2024, 60,263 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-013489 · form4-05172024_040536.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 71,998

F1 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan on May 15, 2024. Assuming continuation of employment, these restricted stock units will vest as to 25% of the shares granted on each of May 15, 2025, May 15, 2026, May 15, 2027, and May 15, 2028.

F2 · balance_after: Of the shares held following this grant on May 15, 2024, 46,019 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-007504 · form4-03112024_040314.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 57,754

F1 · balance_after: Of the shares held as of March 11, 2024, 31,775 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-006101 · form4-03012024_040301.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 57,314

F4 · kind: This forfeiture of shares for tax withholding purposes relates to the vesting on February 28, 2024 of PRSUs granted to the executive in May 2023. Of the units granted, 135% were determined to be earned by the executive pursuant to a resolution of the Axcelis Technologies, Inc. Compensation Committee on February 8, 2024, and half of the earned shares vested on February 28, 2024. As agreed with the executive, the shares issued to the executive on vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested PRSUs.

F2 · price: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of PRSUs on February 28, 2024.

F5 · balance_after: Of the shares held as of February 28, 2024 after the vesting of both the 2022 Performance RSUs and 2023 Performance RSUs, 31,775 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001415889-24-006101 · form4-03012024_040301.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · PRESIDENT AND CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 60,233

F1 · kind: This forfeiture of shares for tax withholding purposes relates to the vesting on February 28, 2024 of the remainder of performance based restricted stock units ("PRSUs") granted to the executive in May 2022. These shares were determined to be earned by the executive pursuant to a resolution of the Axcelis Technologies, Inc. Compensation Committee on February 16, 2023, and half of the earned shares vested on February 28, 2023. As agreed with the executive, the shares issued to the executive on the vesting were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested PRSUs.

F2 · price: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of PRSUs on February 28, 2024.

F3 · balance_after: Of the shares held as of February 28, 2024 after the vesting of the 2022 PRSUs and before the vesting of the 2023 PRSUs, 39,887 were issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-048639 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 57,787

F1 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $179.00 to $179.41, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F2 · balance_after: Of the shares held as of September 7, 2023, 39,650 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-035383 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 61,192

F1 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $173.41 to $173.42, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F2 · balance_after: Of the shares held as of June 8, 2023, 39,650 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-032151 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 64,701

F1 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $153.11 to $153.14, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F2 · balance_after: Of the shares held as of May 25, 2023, 39,650 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-030594 · doc4.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 69,681

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units.

F4 · balance_after: Of the shares held after this tax withholding forfeiture (and related vesting) on May 17, 2023, 39,650 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-029947 · doc4.xml · nonDerivative · entry 5

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 71,239

F9 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $130.76 to $130.80, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F10 · balance_after: Of the shares held after this sale on May 16, 2023, 43,161 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-030594 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 70,586

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units.

F3 · balance_after: Of the shares held after this tax withholding forfeiture (and related vesting) on May 16, 2023, 41,690 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-029947 · doc4.xml · nonDerivative · entry 4

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 79,548

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F5 · acquired: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units.

F8 · balance_after: Of the shares held after this second tax withholding forfeiture (and related vesting) on May 15, 2023, 43,161 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-029947 · doc4.xml · nonDerivative · entry 3

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 80,947

F6 · price: Represents the closing price of the common stock on the date of the tax withholding.

F5 · acquired: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units.

F7 · balance_after: Of the shares held after this first tax withholding forfeiture (and related vesting) on May 15, 2023, 46,314 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-029947 · doc4.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 82,409

F3 · price: In this grant under the Company's 2012 Equity Incentive Plan, the executive may earn shares of common stock, ranging from zero to 150% of the granted units. The shares are earned based on the achievement of 2023 performance goals. Assuming continuation of employment,50% of the earned shares will vest on February 28, 2024 and 50% of the earned shares will vest on February 28, 2025. Unearned restricted stock units will forfeit on February 28, 2024.

F4 · balance_after: Of the shares held after this second grant on May 15, 2023, 49,610 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-029947 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 70,391

F1 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan. Assuming continuation of employment, 25% of these restricted stock units will vest on each of May 15, 2024, May 15, 2025, May 15, 2026 and May 15, 2027.

F2 · balance_after: Of the shares held after this first grant on May 15, 2023, 37,592 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-014090 · doc4.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · EVP, Global Cust & Eng Ops

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 58,373

F4 · kind: This forfeiture of shares for tax withholding purposes relates to the vesting on February 28, 2023 of the first half of shares earned under performance based restricted stock units granted to the executive in May 2022. These shares were determined to be earned by the executive pursuant to a resolution of the Axcelis Technologies, Inc. Compensation Committee on February 16, 2023. The second half of the shares earned under this restricted stock unit award will vest on February 28, 2024, assuming continuation of the executive's services. As agreed with the executive, the shares issued to the executive on the vested shares were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested shares.

F2 · price: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units on February 28, 2023.

F5 · balance_after: Of the shares beneficially owned by the executive on February 28, 2023 after the vesting of shares issued on both the 2021 performance based restricted stock units and the 2022 performance based restricted stock units, 25,574 shares were issuable on vesting of restricted stock units which are subject to forfeiture.

SEC source: 0001209191-23-014090 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · EVP, Global Cust & Eng Ops

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 59,885

F1 · kind: This forfeiture of shares for tax withholding purposes relates to the vesting on February 28, 2023 of the remainder of performance based restricted stock units granted to the executive in May 2021. These shares were determined to be earned by the executive pursuant to a resolution of the Axcelis Technologies, Inc. Compensation Committee on February 15, 2022, and half of the earned shares vested on February 28, 2022. As agreed with the executive, the shares issued to the executive on the vested shares were reduced by a number of shares having a value equal to the executive's tax withholding obligation with respect to the vested shares.

F2 · price: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units on February 28, 2023.

F3 · balance_after: Of the shares beneficially owned by the executive on February 28, 2023 after the vesting of the 2021 performance based restricted stock units, 29,544 shares were issuable on vesting of restricted stock units which are subject to forfeiture. This number includes 3,970 shares issuable under the executive's 2022 performance based restricted stock units, which also vested on February 28, 2023.

SEC source: 0001209191-23-008712 · doc4.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · EVP, Global Cust & Eng Ops

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 59,663

F3 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $126.13 to $126.36, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F2 · balance_after: Of the shares held as of February 13, 2023, 33,605 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-23-008712 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · EVP, Global Cust & Eng Ops

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 60,185

F1 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $125.12 to $126.09, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F2 · balance_after: Of the shares held as of February 13, 2023, 33,605 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-22-056381 · doc4.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · EVP, Global Cust & Eng Ops

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 69,293

F3 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $74.07 to $74.60, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F2 · balance_after: Of the shares held as of November 10, 2022, 33,605 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-22-056381 · doc4.xml · nonDerivative · entry 1

Low Russell · CIK 0001689237 · EVP, Global Cust & Eng Ops

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 71,140

F1 · price: The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $73.07 to $74.05, inclusive. The reporting person undertakes to provide to Axcelis Technologies, Inc., any security holder of Axcelis Technologies, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

F2 · balance_after: Of the shares held as of November 10, 2022, 33,605 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-22-030105 · doc4.xml · nonDerivative · entry 6

Low Russell · CIK 0001689237 · EVP, Engineering

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 76,993

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units.

F10 · balance_after: Of the shares held after this tax withholding forfeiture (and related vesting) on May 17, 2022, 33,605 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-22-030105 · doc4.xml · nonDerivative · entry 5

Low Russell · CIK 0001689237 · EVP, Engineering

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 77,898

F8 · price: In this grant under the Company's 2012 Equity Incentive Plan, the executive may earn shares of common stock, ranging from zero to 150% of the granted units. The shares are earned based on the achievement of 2022 performance goals. Assuming continuation of employment,50% of the earned shares will vest on each of February 28, 2023 and February 28, 2024. Unearned restricted stock units will forfeit on February 28, 2023.

F9 · balance_after: Of the shares held after this second grant on May 16, 2022, 35,645 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-22-030105 · doc4.xml · nonDerivative · entry 4

Low Russell · CIK 0001689237 · EVP, Engineering

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 72,016

F6 · price: These shares are issuable on vesting of restricted stock units granted under the Company's 2012 Equity Incentive Plan. Assuming continuation of employment, 25% of these restricted stock units will vest on each of May 16, 2023, May 16, 2024, May 16, 2025 and May 16, 2026.

F7 · balance_after: Of the shares held after this first grant on May 16, 2022, 29,763 were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-22-030105 · doc4.xml · nonDerivative · entry 3

Low Russell · CIK 0001689237 · EVP, Engineering

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 66,134

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units.

F5 · balance_after: Of the shares held after this tax withholding forfeiture (and related vesting) on May 16, 2022, 23,881 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.

SEC source: 0001209191-22-030105 · doc4.xml · nonDerivative · entry 2

Low Russell · CIK 0001689237 · EVP, Engineering

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 67,036

F2 · price: Represents the closing price of the common stock on the date of the tax withholding.

F1 · acquired: These shares were withheld by the Company to cover the tax withholding obligations of the executive on the vesting of restricted stock units.

F4 · balance_after: Of the shares held after this second tax withholding forfeiture (and related vesting) on May 15, 2022, 25,914 shares were issuable on vesting of restricted stock units granted to the executive under the 2012 Equity Incentive Plan and are subject to forfeiture.