Form 4 Filing for Christopher Tatnall

On May 20, 2026, Christopher Tatnall, EVP Global Customer Operations at AXCELIS TECHNOLOGIES INC (ACLS), reported a disposition of 1,166 shares of common stock at a price of $149.75 per share. This transaction resulted in a post-transaction ownership of 27,627 shares. Of the shares held after this sale, 20,871 shares were issuable upon vesting of restricted stock units and are subject to forfeiture, as noted in footnote F1.