X0609 4 2026-06-03 0001113232 AXCELIS TECHNOLOGIES INC ACLS 0001338515 Sayiner Necip false C/O AXCELIS TECHNOLOGIES, INC. 108 CHERRY HILL DRIVE BEVERLY MA 01915 true false false false 0 Common Stock 2026-06-03 4 S 0 1586 157.4422 D 7112 D The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $157.4100 to $157.7100, inclusive. The reporting person undertakes to provide to the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price. Of the shares held after this sale on June 3, 2026, 2,110 shares were 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 2026-06-04