X0609 4 2026-06-15 0001113232 AXCELIS TECHNOLOGIES INC ACLS 0001979418 Blumenstock Gerald M false C/O AXCELIS TECHNOLOGIES, INC. 108 CHERRY HILL DRIVE BEVERLY MA 01915 false true false false EVP, Research, Dev. & Eng. 0 Common Stock 2026-06-15 4 F 0 506 191.60 D 19987 D This forfeiture of shares for tax withholding purposes relates to the vesting on June 15, 2026 of service vesting restricted stock units granted to the executive in June 2023. The shares issued to the executive following 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. Represents the closing price of the common stock on the date of the tax withholding. Of the shares held after this vesting event on June 15, 2026, 19,447 shares are issuable on vesting of restricted stock units granted to the reporting person under the 2012 Equity Incentive Plan and are subject to forfeiture. /s/ Eileen J. Evans, Attorney-in-Fact 2026-06-16