Axcelis Technologies EVP Greg Redinbo's RSU Vesting and Tax Withholding Transactions

This Form 4 filing reports transactions by Greg Redinbo, EVP of Marketing and Applications at Axcelis Technologies, related to the vesting of restricted stock units (RSUs) granted in May 2022. On May 18, 2026, Redinbo disposed of 190 shares of common stock (111 shares and 79 shares in two separate transactions) at $146.24 per share to cover tax withholding obligations associated with the RSU vesting that occurred on May 16, 2026. The shares were forfeited for tax withholding purposes rather than being sold on the open market. Following these transactions, Redinbo's direct holdings decreased to 35,103 shares and then to 35,024 shares, with a significant portion (20,756 and 20,488 shares respectively) still subject to forfeiture as they represent unvested RSUs under the company's 2012 Equity Incentive Plan. The filing represents routine executive compensation activity related to equity award vesting and tax compliance.