X0303 4 2011-02-10 0 0001041577 ATMI INC ATMI 0001136879 NEUGOLD DOUGLAS A 6 COMMERCE DR DANBURY CT 06810 1 1 0 0 Chairman, President and CEO Common Stock 2011-02-10 4 A 0 28680 0 A 129541 D Common Stock 2011-02-10 4 A 0 14340 0 A 143881 D Common Stock 2011-02-11 4 F 0 1182 18.40 D 142699 D Non-Qualified Stock Option (right to buy) 18.48 2011-02-10 4 A 0 48314 0 A Common Stock 48314 48314 D Performance-based restricted shares ("PRSAs") can be earned based upon the Company's achievement of certain targets. Any PRSAs so earned are subject to time-based vesting, ratably over four years from the grant date. The restricted shares vest 50% on the third anniversary of the grant date, and 25% on each of the fourth and fifth anniversaries of the grant date. Disposition of shares back to the Company to satisfy minimum withholding tax obligations related to restricted stock vesting on February 11, 2011. Non-qualified stock options vest ratably on each anniversary date over four years from the grant date and expire on the tenth anniversary of the grant date. /s/ Ellen T. Harmon, atty-in-fact 2011-02-14